Genetic Disorders Flashcards
What are the features of Joubert syndrome
Classic features
- Abnormal brain (molar tooth sign)
- Hypotonia
- Developmental delays
- Ataxia
- Episodic tachypnea (rapid breathing), apnea
- Atypical eye movement (nystagmus, oculomotor apraxia)
- Speech apraxia
- Abnormal EEG, seizures
- Autism, behavior issues, variable cognitive impairment
- Obesity
- Scoliosis
- Isolated growth hormone deficiency, thyroid hormone deficiency
- Conductive hearing loss
- Tongue hypertrophy
- Situs inversus
- Long face, bitemporal narrowing, high-arched eyebrows, ptosis, prominent nasal bridge, triangle-shaped mouth, prognathism, low-set ears
Other types may also include
- Ocular defect (such as leber congenital amaurosis)
- Renal defect (including cystic kidney disease)
- Renal and ocular, with possible congenital hepatic fibrosis
- Hepatic defect (congenial hepatic fibrosis)
- Also see colobomas and nephronophthisis
- Orofacialdigital defect (tongue hamartomas, oral frenulae, polydactyly, cleft lip/palate)
How is Joubert syndrome inherited?
Autosomal recessive, x-linked recessive, or digenic
21 genes associated
What are the critical genes for 15q11.2 deletion syndrome?
CYFIP1, NIPA2, NIPA1
What are the features of 15q11.2 deletion syndrome?
- Physical features (may or may not be present)
- Broad forehead
- Hypertelorism
- Slender fingers
- Features
- Congenital heart defect
- Hypotonia
- Developmental & speech delay
- Intellectual disability
- Seizures
- Dyspraxia
- Ataxia
- Sleep disorders
- Autism spectrum disorder
- Happy demeanor
- OCD, ADHD
What are the features of 15q13.3 deletion syndrome?
Features (HIGHLY VARIABLE, MAY HAVE NO FEATURES)
- Associated with autism spectrum disorders
- Associated with psychiatric disorders (Schizophrenia and bipolar)
- Intellectual disability
- Speech delays
- Seizures
- Cardiac defects
- Hyperactivity, poor attention span, mood disorder, impulsive/aggressive behavior
What are the features of 16p11.2 deletion/duplication syndrome?
Features
- Autism
- Development & speech delay
- Behavior problems (ADHD)
- Psychiatric disorders (anxiety, depression, bipolar)
- Possibly birth defects
- Under or overweight
- Seizures possibly
What are the features of DiGeorge syndrome/22q11.2 microdeletion?
Features (CATCH22)
- Cardiac defects
- Tetralogy of fallot, interuped aortic arch type B, truncus arteriosus, VSD
- Abnormal facies
- Prominent tubular nose
- Long fingers
- High arched palate
- upslanting palpebral fissures
- Thymic hypoplasia
- T-cell dysfunction, infections
- Cleft palate
- Hypocalcemia
- Variable intellectual disability
- Psychiatric disorders
- hearing loss
- Renal abnormalities
- Endocrine abnormalities
What do ABCA3 mutations cause and what are the features?
Interstitial lung disease
Cause abnormality in surfactant
present in neonatal period with respiratory distress
Autosomal recessive
How is age-related macular dystrophy inherited?
Multifactorial
Age and family hx make up about 20% of risk
smoking and nutrition have an impact
What is the risk of developing age-related macular dystrophy if you have an affected FDR?
2-4 fold increased risk
What gene is associated with Alagille syndrome and what is the inheritance?
JAG1
autosomal dominant with variable penetrance
What are the features of Alagille syndrome?
Liver
- Bile duct paucity causes green jaundice from direct bilirubin
- leads to pruritus (itchy)
- may have cirrhosis, liver failure
- 10% die from this
Heart
- Peripheral pulmonic stenosis
- 25% die from congenital cardiac disease
Kidneys
- Horseshoe kidneys
Eyes
- Posterior embryotoxin
Bones
- Butterfly vertebrae
- Abnormal ribs
Abnormal lining of blood vessel
- Strokes
- Cerebral bleeds
Xanthomas (buildup of cholesterol over knees, elbows)
- Because cholesterol doesn’t get released from the liver
Poor growth with short stature and low weight
Face
- Triangular face, pointy chin, elfin looking
- low set ears
- broad forehead
- deep eye, hypertelorism
What gene, types of mutations, and inheritance is associated with Albright’s Hereditary Osteodystrophy?
GNAS gene
loss of function mutations
autosomal dominant with imprinting (hormone resistance if inherited from mother)
What are the features of Albright’s Hereditary Osetodystrophy?
Features
- Short
- Obese
- Round face
- Developmental delay
- Recessed 4th and 5th knuckles and toes
- Resistance to PTH, TSH, growth hormone-releasing hormone, gonadotropin if inherited from mom
- Resistance of gonadotropin leads to hypogonadism
What gene and genotype is associated with Alpha-1-Antitrypsin Deficiency?
SERPINA1 gene
ZZ genotype = affected
M & S allele normal and dominant
MZ carriers generally healthy, but can act as a modifier for other liver diseases
What are the features of Alpha-1-Antitrypsin Deficiency?
Liver disease in children
- may or may not be present
- if get to be age 4 or 5 without problems, they are probably fine
- Hepatomegaly because of accumulation of abnormal AAT protein in the liver
Pulmonary disease in adults
- Emphysema, COPD
- Because the AAT protein is trapped in the liver and can’t break down and inactivate carcinogens
Increased risk for hepatocellular carcinoma
Avoid tobacco!
What are the genes associated with Alpha Thalassemia?
HBA1 and HBA2
What are the features of Alpha Thalassemia Trait/Minor/Alpha0?
Two gene deletion
Microcytic anemia
May be confused with iron deficiency
What are the features associated with HbH Alpha Thalassemia major?
3 gene deletion
Features
- Splenomegaly
- bone deformity
- hemolytic and microcytic anemia
- fatigue
What are the features of HbH + HbCS Alpha Thalassemia Major?
2 gene deletion + constant spring variant
Feaures
- Splenomegaly
- bone deformity
- hemolytic and microcytic anemia
- fatigue
- More severe than HbH
What are the features what all 4 Alpha Thalassemia genes are deleted/mutated?
Hydrop Fetalis
All HbBarts
Not compatible with life
What do you see when testing for Alpha Thalassemia?
MCV <80fL
Will see HbBarts on newborn screen
What is the inheritance of Alport syndrome?
Most x-linked recessive
Some autosomal recessive
What are the features associated with Alport syndrome?
Progressive, later-onset sensorineural hearing loss
Kidney problems as presenting feature
- (progressive glomerulonephritis)
Variable eye findings
What gene causes Anderson-Tawill syndrome and what is the inheritance?
KCNJ2
Autosomal dominant with variability
What are the features of Anderson-Tawill syndrome?
Significant cardiac manifestations
- may need a pace maker
- Can have sudden cardiac death
Myotonia (delayed muscle relaxation
What kind of disorder is Anderson-Tawill syndrome and what kind of test results do you see?
Channelopathy
Abnormal long exercise test
normal short exercise test
How is Angelman syndrome inherited?
Loss of functioning maternal UBE3A gene
- deletion most common
- paternal UPD 15
- imprinting center defect (ICD)
- UBE3A mutation (will have normal methylation)
Could be inherited from normal mother if mom inherited a deletion, ICD, or mutation from her father
How do you test for Angelman syndrome?
Methylation study
- If abnormal, can do deletion analysis and/or UPD study to find out mechanism
- If normal but still suspicion, sequence & del/dup UBE3A
What are the features of Angelman syndrome?
Features
- Severe developmental and speech delay
- Receptive communication > expressive
- Hypotonia and feeding difficulties in infancy, tongue thrust or suck/swallowing disorders
- Gait ataxia, wide based gait with hands raised while walking
- Happy demeanor, happy puppet hands
- Fascination with water
- Seizures
- Abnormal sleep cycles
- Absolute or relative microcephaly by age 2
- Prominent chin, wide mouth and wide spaced teeth, hyperpigmented skin, light hair/eyes, scoliosis, constipation
What gene is associated with Ataxia Telangiectasia and how is it inherited?
ATM
Autosomal recessive
Carriers at increased risk for breast cancer
What are the features of Ataxia Telangiectasia?
Features
- Progressive cerebellar ataxia b/w 1-4 years
- Oculomotor apraxia (eyes don’t work in symmetry)
- Frequent infections, immunodeficiency
- Choreoathetosis (dancing type movements that can’t be controlled)
- Telangiectasias of the conjunctivae (lots of vessels in the sclera)
- Increased risk for malignancy
- Leukemia & lymphoma (1/3)
- Sensitive to ionizing radiation
What cancers are associated with BAP1 mutations?
Uveal melanoma
cutaneous melanoma
renal cell carcinoma
mesothelioma
lung adenocarcinoma
meningioma
peritoneal serous adenocarcinoma
What genes are uveal melanoma associated with?
BAP1
BRCA2
CDKN2A
What gene and type of mutations are associated with Becker Muscular Dystrophy?
Dystrophin gene
Majority large deletions
In-frame deletions usually
How is Becker Muscular Dystrophy inherited?
X-linked recessive
What are the features of Becker Muscular Dystrophy?
Loss of ambulation >12 years
Looks like Duchenne Muscular dystrophy, but they do better
Isolated cardiomyopathy
Myalgias (muscle aches)
How is Beckwith-Wiedemann syndrome inherited?
Imprinting on chromosome 11
- Same region as Russel-Silver syndrome
Mom’s copy is missing/mutated or dad’s copy is overexpressed
- 50% hypomethylation of imprinting center 2 (IC2) on maternal copy
- 20% paternal UPD
- can be from gain of methylation of maternal CDKN1C, a microdeletion/duplication, or a translocation/inversion
- Rarely autosomal dominant
What are the features of Beckwith-Wiedemann syndrome?
Features
- Big baby
- Omphalocele
- Prematurity
- Macroglossia
- Asymmetry
- Hypoglycemia
- Umbilical hernia
- Neonatal hypoglycemia
- Ear creases/pits
- Renal abnormalities
- Overgrowth
Tumor risk
- Wilms tumor
- Hepatoblastoma
What tumor risks are associated with Beckwith-Wiedemann syndrome?
Wilms tumors
Hepatoblastoma
What gene is associated with Beta-Thalassemia?
HBB
What are the features of Beta-Thalassemia minor/intermedia?
B+/B+ or B+/B0
Mild anemia
later presentation
at risk for iron overload
What is thhe hemoglobin profile for someone with Beta-Thalassemia trait?
B/B+ or B/B0
A
Elevated A2
Fetal may or may not be elevated
What is the hemoglobin progile for someone with Beta-Thalassemia intermedia/minor?
B+/B+ or B+/B0
Elevated A2
Elevated Fetal
A present
What is the hemoglobin profile for someone with Beta-Thalassemia major?
B0/B0
Elevated A2
Elevated fetal
NO A
What are the features of Beta-Thalassemia major?
B0/B0
Features
- Severe microcytic anemia
- FTT, feeding difficulties, diarrhea
- Frontal bossing, limb shortening, compression fractures of the spine
- Hepatosplenomegaly
- Jaundice
- Iron overload
- Extramedullary hematopoiesis
- Endorine and liver issues
How is biotinidase deficiency inherited?
Autosomal recessive
What are the features of treated biotinidase deficiency?
No features if treated with biotin supplement
What are the features of untreated biotinidase deficiency?
If untreated
- Sensorineural hearing loss
- Seizures
- vision loss
- hair loss
- Hypertonic
- Developmental delay/intellectual disability
- Ataxia
What gene is associated with Bloom syndrome and how is it inherited?
BLM gene
autosomal recessive
AJ founder mutation
What kind of syndrome is Bloom syndrome?
Chromosome breakage syndrome
What is the AJ carrier frequency of Bloom syndrome?
1 in 100 AJ carrier frequency
What are the features of Bloom syndrome?
Features
- Pre- and postnatal growth deficiency
- Microcephaly, dolichocephaly
- malar hypoplasia
- loss of lower lashes
- Little subcutaneous fat
- Facial telangiectatic erythemia & sun sensitive skin
- Areas of hyper- and hypopigmentation
- Possible learning disability, but normal intelligence
- Males infertile, early menopause for women
- More infections due to GER
- Increased risk for DM, cancer, and COPD
How is brahio-oto-renal syndrome inherited?
Autosomal dominant
What are the features of brachio-oto-renal syndrome?
Hearing loss
- conductive, sensorineural, or mixed
External ear abnormalities (pits or severely deformed)
Branchial cleft cysts or fistulae (lump in the neck or collarbone)
Kidney abnormalities
What gene is associated with campomelic dysplasia and what is the inheritance?
SOX9 cartilage gene
Autosomal dominant
What are the features of campoelic dysplasia?
Features
- bent long bones (campomelia)
- short stature
- hearing loss
- scolosis
- Pierre-Robin sequence
- sex reversal in males
- club feet
- problems with cartilage in the trachea
- leads to severe air trapping
How is celiac disease inherited?
Multifactorial
Increased risk wit HLA-DQA1 adn HLA-DQB1 alleles
(3% with one or both of these alleles develops celiac, but 30% of the general population have one of the alleles)
What are the risks of developing Celiac disease if you have an affectd FDR?
5-10% risk if you have an affected FDR
40% risk if you have the same HLA profile as the affected FDR
What are the features of Celiac disease?
Autoimmune disorder to ingestion of gluten
- Leads to inflammation of the small intestine and damage of villi, which can impair nutrient absorption
Signs/symptoms
- Diarrhea, bowel irritability
- Abdominal pain and distention
- Weight loss
- Vitamin deficiency, FTT, short stature, dental/enamel defects
- Chronic fatigue
- Joint pain/inflammation, osteoporosis/osteopenia
- Depression, ADD
- Infertility, fetal loss
- Delayed puberty
- Migraines
What gene is associated with CHARGE syndrome and what is the inheritance?
CDH7 gene
Autosomal dominant
majority de novo
What are the features of CHARGE syndrome?
Coloboma
- Looks like a break in the iris and pupil is coming out
Congenital heart defect
- ASD, VSD, mitral valve defects
Choanal atresia
- Respiratory and feeding problems
Retardation of Growth and mental development
- May mimic autism
- Facial asymmetry, unilateral facial palsy from cranial nerve dysfunction
Genital defects
- Genital hypoplasia, delayed puberty from hypogonadotropic hypogonadism
Ear malformations
- May be deaf
- External and internal malformations
What gene is associated with choroideremia and how is it inherited?
CHM gene
X-linked
Females have milder signs
What is choroideremia?
Progressive choroido-retinal degeneration
How does choroideremia present?
Males present with
- early night blindness (not muc peripheral vision loss)
- Central vision is preserved until later in life
Gene therapy trials
What population has a founder mutation for choroideremia?
Finish
What gene is associated with CLOVES syndrome and how is it inherited?
PIK3CA heterozygous somatic mutations
test skin, saliva, or affected tissue
de novo
What kind of syndrome is CLOVES syndrome?
Lipomatous overgrowth syndrome
What are the features of CLOVES syndrome?
Features
-
Congenital lipomatous asymmetric overgrowth
- Of the trunk, lymphatic, capillary, and venous
- Typically of the thoracic and abdominal wall
- Combined-type vascular malformations
- Low-flow and high-flow vascular and lymphatic malformations
- Epidermal nevi
-
Skeletal and spinal anomalies
- Can have various degrees of intellectual disability because of it
- Renal anomalies
- Tumors
How is CMT1 inherited?
Autosomal dominant
How is CMT2 inherited?
Autosomal dominant
What kind of neuropathy is CMT1?
Demyelinating
- slow nerve conduction velocity
- pathology of nerves has an onion appearance
What kind of neuropathy is CMT2?
Axonal
- nerve conduction velocity near normal
- decreased number of nerves
How is CMT4 inherited and what type of neuropathy is it?
Autosomal recessive
Axonal (decreased number of nerves)
How is CMTX inherited?
X-linked dominant
What is the most common form of CMT?
CMT1A
What gene and type of mutations is associated with CMT1A?
PMP22
Duplications (have 3 copies of PMP22)
- 4 copies of PMP22 is severe CMT1
- (A deletion of PMP22 causes hereditary neuropathy with liability to pressure palsy)
What are the features of CMT1A?
Onset 1st-2nd decade
Slow progression to orthotics
Foot deformities
foot drop
distal muscle weakness
distal muscle atrophy
sensory loss
slow nerve conduction
What genes are associated with Cockayne syndrome and what is the inheritance?
ERCC6 and ERCC2
autosomal recessive
What kind of syndrome is Cockayne syndrome?
Premature aging syndrome
What are the features of Cockayne syndrome?
Features
- Progressive neurological and cognitive dysfunction (demyelination)
- Microcephaly with developmental delay, spasticity, ataxia
- Low birth weight and postnatal growth failure (Cahectic dwarfism)
- Muscle atrophy, weight loss
- Skin photsensitivity
- Dental decay
- Pigmentary retinopathy, optic atrophy, cataracts
- Sensorineural hearing loss
- vision loss, cataracts
- Skeletal abnormalaties (kyphosis, scoliosis)
- Prematurely aged face with deep set eyes and pinched nose
What gene is associated with Congenital Central Hypoventilation syndrome and how is it inherited?
PHOX2B
Caused by a decrease in a triplett repeat
Autosomal dominant
mostly de novo and/or mosaic
What are the features of congenital central hypoventilation syndrome?
Features
- Apnea
- Stop breathing when go to sleep
- Absent respiratory response to hypoxia and hypercapnia, no change in respiratory effort during CO2 inhalation, illness, or exercise
- Profound in sleep, especially non-REM sleep
- Cyanosis
- Cardiorespiratory arrest
- Ophthalmologic abnormalities due to cranial nerves
- Some have hirschprung (specific mutation)
- Neural crest tumors
- Arrhythmias
- Some have seizures & cognitive disability
What is CHRPE (congenital hypertrophy of retinal pigmented epithelium) associated with?
FAP
How is congenital stationary night blindness inherited?
X-linked
Autosomal dominant
Autosomal recessive
what are the features of Congenital Stationary Night Blindness?
Night blindness
Contrast sensitivity
Nystagmus
What gene is associated with Cornelia de Lange and how is it inherited?
NIPBL gene mostly
Autosomal dominant
99% de novo
What are the features of Cornelia de Lange syndrome?
Features
- Growth retardation
- Facial
- Long eyelashes
- Thick eyebrows/synophorus, arched eyebrows
- Upturned nose
- Small widely spaced teeth
- Microcephaly
- Cognitive delay
- Autistic and self-destructive tendencies
- Shortened limbs
- Missing digits
- Genital abnormalities
- GI dysfunction
- Hearing loss
- myopia
- Cardia septal defects (VSD)
What causes Cri-du-Chat syndrome and how is it inherited?
5p-
loss of CTNND2, SEMA5A, possibly TERT
90% de novo, 80% from deletion of paternal copy
What is the sex ratio for Cri-du-Chat syndrome?
4:3 females:males
What are the features of Cri-du-Chat syndrome?
Features
- Cat cry
- Heart defects (VSD, ASD, PDA, Tetralogy of fallot)
- Significant intellectual disability
- Self-injury
- Abnormal sleep patterns
- Microcephaly
- Hypotonia, poor feeding, Cleft lip/palate
- Thymic dysplasia
- Intestinal malrotation, megacolon, inguinal hernia
- Dislocated hips
- Rare renal malformations
- Cryptorchidism, hypospadias
- Hyperextensible joints
- Scoliosis
- Face
- Hypoplastic nasal bridge
- Hypertelorism, down-slanting palpebral fissures, Deep set eyes, prominent supraorbital ridges
- Myopia, cataracts
- Low-set ears with tags and/or fistulas
- Micrognathia, cleft lip/palate
- Short fingers
- 2,3 syndactyly of hands and/or feet
- Club feet, flat feet
How is Crohn’s disease inherited?
Multifactorial
29 genes, SNPS, and HLA status important
Environment, lifestyle, diet important
What are the symptoms of Crohn’s Disease?
Signs and symptoms
- Weight loss, loss of appetite
- Fever
- Fatigue, night sweats
- Loss of normal menstrual cycle
- Mouth ulcers
- Abdominal pain, diarrhea, bowel obstruction, rectal bleeding
Crohn’s disease
- Mostly affects the ileum and entire thickness of the bowel wall
- Can affect GI system anywhere from mouth to anus, and can “skip” areas
Ulcerative colitis
- Affects the innermost lining of the colon/large intestine with no skipping
What are the main features of cystic fibrosis?
Lung disease from increased mucus
- Poor genotype/phenotype correlation
- Infection
Pancreatic insufficiency
- Severe, classic mutations lead to pancreatic insufficiency
- Milder, nonclassic mutations lead to pancreatic sufficiency
Infertility in males (>97%)
- May be only feature
What are some symptoms of cystic fibrosis?
Features/signs
- Affects the whole body
- Night blindness
- Can’t digest fat, so vitamins don’t get absorbed
- Sterility in males due to CBAVD & decreased fertility in females
- Digital clubbing
- Osteoporosis
- Diabetes
- Cirrhosis
- Dry, salty skin
- Chronic pain
- Liver disease
- Can be associated with diabetes
How do you test for cystic fibrosis?
First line testing is sweath chloride test
Then do a panel of common mutations
- can reduce carrier risk to 1 in 240
Can also do sequencing and del/dup
- Can reduce carrier risk to 1 in 2500
- Is this worth it for the family?
What gene is associated with cystic fibrosis and how is it inherited?
CFTR
autosomal recessive
What type of mutations are Class I CFTR mutations and how do you treat it?
Reduced or absetn transcription and protein
Read through therapy
What kind of mutations are Class II CFTR mutations and how do you treat it?
Protein is made, but it isn’t processed correctly and gets destroyed immediately. Never makes it to the cell surface
Gets destroyed becuase of protein misfolding, incomplete/incorrect post-translational modifications, or error in protein trafficking
Therapy would be correctors to help the protein fold properly and get to the cell surface
DeltaF508
What type of mutations are Class III CFTR mutations and how do you treat it?
Protein is made and it gets to the cell surface, but it doesn’t function properly
Treat with Kalydeco
What type of mutations are Class IV CFTR mutations?
Protein is made and gets to the cell surface, but it doesn’t work as well as it should. It is a little functional, though
R117H
- If cis poly-T tract is 5T, it is disease causing because affects folding & gives alternate splicing
- Having a higher TG tract with 5T makes it more likely to be disease causing because it leads to skipping of exon 9
What kind of mutations are Class V CFTR mutations?
There is reduced synthesis/protein production because of alternative splicing
What type of mutations are Class VI CFTR mutations?
Protein gets to the cell surface, but it is unstable and quickly get degraded
Rescued DeltaF508
What class of mutation is the CFTR DeltaF508?
Class II
Protein is made, but isn’t processed quickly and quickly gets destroyed
Once it has been treated with a corrector (helps fold the protein), it becomes a Class VI mutations (protein gets to the cell surface, but then gets quickly degraded)
What class of mutation if CFTR G551D and how do you treat it?
Class III (protein is made and gets to the cell surface, but it doesn’t function properly)
Treat with Kalydeco
Accounts for 4% of CF mutations
Explain pathogenicity of the poly-T tract and TG-tract in CFTR
Poly T tract:
- The lower the poly T tract (5T), the more likely it is to be pathogenic
- 5T, and potentially 7T can be pathogenic when in cis with R117H
- Homozygous 5T can be at risk for male infertility
- Lower T-tract is pathogenic because it can cause skipping of exon 9
TG-tract
- Only pathogenic when in combination with 5T poly-T tract
- The higher the TG-tract is (12 or 13), the more likely it is to be pathogenic when combined with 5T
- 5T with 12 or 13 TG tract without R117H mutation can cause nonclassic disease
- A higher TG tract can lead to skipping of exon 9
What gene is associated with Connexin 26 and how is it inherited?
GJB2
Autosomal recessive
What features is Connexin 26 associated with?
Non-syndromic congenital sensorineural hearing loss
(DFNB1)
Milder presentation for compound heterozygotes
What percentage of hearing loss is due to Connexin 26?
10-15% of all hearing loss
50% of autosomal recessive hearing loss
What is the carrier frequency for Connexin 26?
1 in 31-35 for Caucasians
1 in 21-25 for AJ
How is diabetes inherited?
Multifactorial
- Genetics (stronger for Type II)
- diet, exercise, weight (74% of risk for Type II)
- HLA status
What type of diabetes has a stronger genetic component?
Type II
What is the chance of developing diabetes if you have one parent with Type II diabetes?
1 in 10
What is the chance of developing diabetes if you both parents have Type II?
1 in 2
How is MODY inherited?
Autosomal dominant
What percentage of diabetes is MODY?
1-2% of diabetes is MODY
Why is it important to identify MODY?
MODY has an effective treatment (sulfonylureas), which does not work for other types of diabetes
How is DICER1 inherited?
Autosomal dominant
What cancers are associated with DICER1 mutations?
Pleuropulmonary blastoma (PPB)
Cystic nephroma
Ovarian Sertoli-Leydig tumor
Other sex-cord stromal tumors
Wilms tumor (rare)
Intraocular medulloepithelioma
Nasal chondromesenchymal hamaroma (present with stuffy nose)
Thyroid (nodular thyroid hyperplasia, differentiated thyroid carcinoma)
Embryonal rhabdomyosarcoma
Intestinal hamartomatous polyps
When is the cancer risk greatest for DICER1 mutations?
The cancer risk is greatest when young
How does pleuropulmonary blastoma (PPB) present and what should you test for when you see it?
PPB may present as a spontaneous pneumothorax
Test for DICER1
60-70% of these cases are from DICER1 mutations
What should you test for when you see a cystic nephroma?
DICER1
90-100% are due to DICER1 mutations
2/3 of cystic nephroma cases without a family history of PPB have a DICER1 mutation
What should you test for when you see an ovarian sertoli-leydig tumor?
DICER1
What gene, types of mutations, and inheritance is associated with Duchenne Muscular dystrophy?
Dystrophin gene
Out of frame deletions
X-linked recessive
What are the features of Duchenne Muscular Dystrophy?
Features/presentation
- Inability to run/keep up around age 3
- Gower maneuver
- Difficulty climbing stairs
- Gait abnormalities/toe walking
- Calf hypertrophy (pseudohypertrophy from fatty infiltration)
- Proximal leg weakness, progressing to arms
- Wheelchair confined by age 12
- Can’t life arms very high
- Scoliosis because muscles can’t hold them up
- Squishes lungs and leads to respiratory issues
- Sleep disorders due to extra shallow breathing
- Can’t take deep breaths or cough properly
- Dilated cardiomyopathy
- Mild obesity (because of steroids)
- Mild mental retardation
- CK levels 50-100x normal
- Death due to pneumonia or congestive heart failure (DCM) in 20s
What are the features of a female carrier of Duchenne Muscular dystrophy?
Muscle aches
May have elevated CK levels
May be more severely effective due to mosaicism (10%) or skewed X-inactiation
If a boy is a simplex case of Duchenne muscualr dystrophy, what are the chances his mom is a carrier?
2/3 (1/3 of cases are de novo)
What are some potential therapies being researched for Duchenne muscular dystrophy?
Stop codon readthrough
Exon skipping therapies
- Make an out of frame deletion and in-frame to give BMD phenotype
- Restores reading frame in ~13%
- Gives some expression of dystrophin
Gene transfer therapy
- Myostatin inhibitor to get hypertrophy
- Decreases severity of disease
Gene replacement
- Mini-dystrophin in vector
Surrogate gene transfer of Galgt2
- Restores CK levels
- Doesn’t induce immunity because the gene is already expressed
What are the features of Classic EDS (Type 1) and how is it inherited?
COL5A1 gene, autosomal dominant
Features
- Skin hyperextensibility
- fish mouth or cigarette paper scars
- joint hypermobility
What are the featues of EDS Type 3 (Hypermobile type)?
Major criteria
- Smooth, velvety skin
- Joint hypermobility
Minor criteria
- Chronic joint/limb pain
- Recurrent joint dislocations
- Positive family hx
Other features
- Narrow, high arched palate
- Scoliosis
- Flat feet
- Valgus deformity
- Marfanoid habitus, but don’t meet Marfan criteria
- Pectus excavatum (carinatum more rare)
- Constipation, IBS, GER
- Family hx of fibromyalgia
How is EDS Type 3 (Hypermobile type) inherited and diagnosed?
Autosomal dominant
Clinical dx only, no known gene
What gene is associated with EDS Type 4 (vascular type) and how it is inherited?
COL3A1
Autosomal dominant
What are the features of EDS Type 4 (vascular type)?
Features
- Arterial, bowel, and uterine ruptures
- Pneumothorax
- Postpartum bleeding
- Lobeless ears
- Acrogeria (premature aging, hands may look really old)
- Translucent skin (seen veins)
- A little bit of joint hypermobility
What type of disorder is Farbry disease?
Lysosomal storage disorder
What gene is associated with Fabry disease and how is it inherited?
GLA gene
X-linked recessive with varied symptoms in females
What are the features of Fabry disease?
Features
- Pain in distal extremities
- Heat intolerance
- Angiokeratomas on trunk
- GI dysfunction
- Renal disease
- Cardiomyopathy
- Stroke
How can you treat Fabry disease and how does it help?
ERT available, but not 100% effective
- Decreases vascular lesions
- Increases renal and myocardial function
- Decreases pain
- Increases heat/cold tolerance by improving nerve conduction
- Improve exercise intolerance
- Improves quality of life
What are the genetics behind facio-scapulo-humeral muscular dystrophy?
4q35 regions
Need to do southern blot to detect
D4Z4 repeat encodes DUX4
- Causes myopathy via a p53 dependent pathway
Get disease when have reduce repeats (1-10) and 4QA allele (makes poly-A tail)
Not a trinucleotide repeat where size varies between generations
1:20,000-435,000
What are the features of facio-scapulo-humeral muscular dystrophy (FSHMD)?
Facial weakness
- Tapered lip, can’t smile well, can’t squeeze eyes shut, chiseled cheek bones, can’t pucker lips, many can’t drink through a straw
Scapula stick out
Peroneal and hip girdle weakness later
Weakness in pectoral muscles and biceps
- Atrophic biceps with maintained deltoids
Can’t lift arms very high
Hypertrophy of forearms
Sensorineural deafness
Retinal vascular tortuosity possible
Absent brachio-radialis
Bulbar, extraocular, and respiratory muscles spared
asymetric onset and progression
Relatively normal CK
What is the Factor V Leiden mutation?
F5 gene
p.Arg506Gln, 1691G>A
What are the risks associated with Factor V Leiden?
Venous thromboembolism (VTE) (deep vein thrombosis)
- Heterozygous: 3-8x increased risk for VTE (<10%)
- Homozygous 50-80x increased risk for VTE (<10%)
- Risk increases with age
- No impact on risk for a recurrent VTE
Pulmonary emboism
Small increased risk (2-7 fold increased risk) for pregnancy loss and pregnancy complications
Other risk factors include pregnancy, oral contraceptives/HRT, cancer, age, obesity, surgery, injury
What gene is associated with FAP and how is it inherited?
APC (many mutations not detected)
Autosomal dominant
When should you test for FAP?
Age 10-12
What risks are associated with FAP?
Colon cancer
- 100s-1000s of polyps
- risk 100% if untreated
Extracolonic tumors
- Upper GI
- Desmoid
- Osteoma
- Thryoid
- Brain
- Soft tissues tumors
- hepatoblastoma
- 2% risk
- CHRPE
- Dental anomalies
What gene is associated wtih Familial Mediterranean Fever and how is it inherited?
MEFV gene (sequence only)
Autosomal recessive
High carrier frequency in Turkey & North African Jewish (1:5), and Armenian (1:7)
What are the features of Familial Mediterranean Fever?
Features
- Recurrent fevers in childhood may be only manifestation
- Abdominal attacks (90%)
- Recurrent, acute fevers with intense abdominal pain
- Articular attacks (75%)
- High fever and joint pain, can lead to chronic joint pain
- Pleural attacks (45%)
- High fever with chest pain & painful breathing
- Erysipelas-like erythema
- Lesion on lower limb often accompanied by a fever or arthritis
- Amyloidosis (Build up of AA amyloids in kidneys)
- can lead to end stage renal disease (presents with proteinuria)
How is Fanconi Anemia inherited and what are some genes associated with it?
Mostly autosomal recessive
FANCB is X-linked
Homozygous BRCA2 and PALB2 cause Fanconi anemia
FANCC gene has a common AJ mutation
15 genes
What type of syndrome is Fanconi Anemia?
Chromosome breakage syndrome
What are the features of Fanconi Anemia?
Features
- Progressive bone marrow failure (usually in 1st decade, 90% by 4th-5th decade)
- Short stature
- Abnormal skin pigmentation, Café-au-lait spots
- Skeletal, thumb, forearm malformation, radial ray anomalies
- Ocular issues
- Kidney/urinary disease, GI abnormalities
- Hearing loss
- Heart defects (VSD)
- Developmental delay
- Underdeveloped pituitary, hypogonadism
- Cancer
- Hemotolagic (10-30%)
- Head and neck, GI, genital tract (25-30%)
What gene is associated with fibroadipose hyperplasia and how is it inherited?
PIK3CA heterozygous somatic mutations
(test skin, saliva, or affected tissue)
De novo
What kind of syndrome is fibroadipose hyperplasia?
Lipomatous overgrowth syndrome
What are the features of fibroadipose hyperplasia?
Features
- Cutaneous capillary vascular malformations
- Testicular or epidymal abnormalities
- Epidermal nevi
- Polydactyly
How common is autism in Fragile X syndrome?
25% have an autism spectrum disorder
What are the features of Frasier Syndrome?
Genetically male (XY)
ambiguous genitalia
kidney problems (focal segmental glomerulosclerosis)
gonadoblastoma
Wilms tumor
What gene is associated with Galactosemia and how is it inherited?
GALT gene
autosomal recessive
What kind of disorder is galactosemia and how is it treated?
Disorder of carbohydrate metabolism
Treat by eliminating galactose from the diet
What are the features of galactosemia?
Features
- Failure to thrive
- Hepatomegaly
- Cataracts
- Speech and developmental problems when not treated
- Vomiting, diarrhea, dehydration
What gene is associated with Gaucher and how is it inherited?
GBA gene
autosomal recessive
What kind of disorder is Gaucher disease?
Lysosomal storage disorder
What are the features of Gaucher disease?
Features
- Hepatosplenomegaly
- Cytopenia
- Gaucher cells (pathoneumonic)
- Erlenmeyer flask shape to bones
- Vascular necrosis
How do you treat Gaucher Disease and how does it help?
Enzyme replacement therapy available
- Decreases hepatosplenomegaly
- Improves liver and spleen function
- Improves bone manifestations
- Helps with growth
Do you test for glaucoma?
No
What gene is associated with hemochromatosis and how is it inherited?
HFE gene
(C282Y adn H63D)
Autosomal recessive
What are the features of hemochromatosis?
Increased iron accumulation
- can lead to diabetes
- hyperpigmentation of skin (bronze)
- arthritis
- CV issues
Treat with phlebotomy
What genes (protein deficieny) are associated with hemophilia, how is it inherited, and which typie is more common?
F8 gene, Factor VIII deficiency, Hemophilia A, most common
F9 gene, Factor IX deficiency, Hemophilia B
X-linked
What are the symptoms of a hemophilia carrier, and what is the chance of being a carrier?
Symptoms
- Mild hemophilia
- menorrhagia
- bleeding with tooth extraction, trauma, etc
- easy bruising
Obligate carrier is father is affected, 2 sons affected or 1 affected sone and 1 affected maternal relative
If son is a simplex case
- 30% chance the son is a de novo case
- Mom could have a de novo mutation
- common with inversion 22, which occurs during spermatogenesis 90% of the time
- Mom could have inherited it from her mom
What are the features of hemophilia?
Hemorrhage (spontaneous or with incidental injury)
Joint or deep muscle bleeds (severe)
bleeding after mild trauma, minor procedures, surgery
Severe <1% factor
Modertae 1-5% factor
Mild 6-35% factor
When/why would you do genetic testing for hemophilia?
Carrier screening, prenatal testing, or confirming a diagnosis
To figure out inhibitor risk
- Genotype/phenotype correlation with this
- inversion22 has a high risk for inhibitors
What gene & mutation is associated with Hereditary Neuropathy with Liability to Pressure Palsy (HNPP)?
Deletion of PMP22 (only have 1 copy of PMP22)
Can also be PMP22 point mutations
(Duplication of PMP22 causes CMT1A)
What are the features of Hereditary Neuropathy with Liability to Pressure Palsies?
- Young adult onset
- mild axonal peripheral neuropathy
- tomauli are a pathological hallmark (looks like sausages)
What genes are associated with hereditary pancreatitis?
CFTR
PRSS1
SPINK-1
What are some features of Hermansky-Pudlak?
May appear like albinism
normal or decreased vision
Many die from bleeding diathesis
2 founder mutations in Puerto Rico
What gene is associated with Hunter syndrome and how is it inherited?
IDS gene
x-linked
What type of disorder is Hunter syndrome?
Mucopolysaccharidosis
What are the features of Hunter syndrome?
Features
- Coarse facial features (gets worse over time)
- Hepatosplenomegaly
- Joint contractures
- Developmental delay/intellectual disorders
- Limited range of motion
How is Hunter syndrome treated and what does it help?
ERT available
- Decreases GAGS
- Improves hepatosplenomegaly
- Improves airway problems (often have storage in their airway)
- Improves sleep apnea
- Improves motor function
- Improves myocardial function
- Improves range of motion in joints
- Give better growth rate
What gene & types of mutations are associated with Huntington Disease, and how is it inherited?
HTT gene
Autosomal dominant with anticipation
CAG trinucleotide repeat
- 10-27 repeats normal
- 28-35 repeats normal, but risk for expansion
- 36-39 reduced penetrance, risk for expansion
- 40+ repeats=disease
What are the features of Huntington Disease?
Features
- Progressive neurodegeneration
- Unseteady gait and involuntary movements
- Personality changes, mood swings, outbursts, depression, OCD
- Forgetfulness, impaired judgement, decreased memory, reasoning, and concentration
- Slurred speech and difficulty swallowing
- Onset 30s-40s, live 15-20 years after onset
What gene is associated with Hurler syndrome and how is it inherited?
IDUA
autosomal recessive
What kind of disorder is Hurler syndrome?
Mucopolysaccharidosis
What are the features of Hurler syndrome?
Features
- Coarse facial features
- Hepatosplenomegaly
- Corneal clouding
- Joint contractures & limitations
- Developmental delay/intellectual disorders
- Macroglossia
- Dysostosis multiplex (bone involvement)
- Deafness
- Valvular heart disease
How is Hurler syndrome treated and what does it help with?
Bone marrow transplant
ERT available
- Decreases GAGS
- Improves hepatosplenomegaly
- Improves airway problems (often have storage in their airway)
- Improves sleep apnea
- Improves motor function
- Improves myocardial function
- Improves range of motion in joints
- Give better growth rate
What is the difference between Hunter syndrome and Hurler syndrome?
Hunter syndrome is X-linked
Hurler syndrome has corneal clouding
What gene is associated with Hyperkalemic Periodic Paralysis and how is it inherited?
SCN4A gene
Autosomal dominant
What are the features of Hyperkalemic Periodic Paralysis?
- Periodic paralysis
- triggers include exercise, fasting, or cold exposure
- myotonia
- Problems with anesthesia
- Inconsistently high serum potassium levels
What kind of disorder is Hyperkalemic Periodic Paralysis and what tests can be done to look for it?
Channelopathy
Abnormal long exercise test, normal short exercise test
What genes are associated with Hypohidrotic Ectodermal Dysplasia and how is it inherited?
EDA, X-linked, most common
EDAR, autosomal recessive
EDARADD, autosomal dominant
IKKG, NEMO, X-linked (immune deficiency)
What are the features of hypohidrotic ectodermal dysplasia?
Features
- Thin, peely skin
- Fine, dry hair, doesn’t grow well, abnormal pattern (HYPERTRICHOSIS)
- Don’t sweat (HYPOHIDROSIS)
- Hypoplastic or absent mucous glands
- Hypodontia or anodontia with conical shaped teeth (HYPODONTIA)
- May have low immune system with recurrent infections
What gene is associated wtih hypokalemic periodic paralysis and how is it inherited?
CACNA1S and SCN4A
Autosomal dominant
What kind of disorder is hypokalemic periodic paralysis and what test can you do to look for it?
Channelopathy
abnormal long exercise test, normal short exercise test
What are the features of hypokalemic periodic paralysis?
- Hours to days of muscle weakness
- Can awak with paralysis
- usually hours after exertion or a carbohydrate rich meal
- Low potassium levels
- can have problems with anesthesia
- NO myotonia present
What gene is associated wtih Incontinentia Pigmenti and how is it inherited?
IKBKG gene
X-linked dominant
lethal in males
What are the features of Inconteinentia Pigmenti?
Skin lesions
- Progress from herpes appearing lesions, to severe burn appearing lesions, to hyperpigmentation, to hypopigmented lesions
CNS Problems
- developmental delay (including cognitive)
- seizures
- microcephaly
- spasticity
- paralysis
Dental manifestations
- Late dentition, hypodontia, conical teeth
Ocular manifestations
- Strabismus, neovascularization, microphthalmos, optic nerve atrophy, cataracts, glaucoma
What causes Jacobsen syndrome?
11q terminal deletion
slightly more common in females
What are the features of Jacobsen syndrome?
Features
- Heart defects (VSD, hypoplastic left heart)
- Kidney defects
- FTT, feeding difficulties, pyloric stenosis
- Recurrent infections (ear, respiratory)
- Short stature, skeletal abnormalities
-
High bleeding risk (Paris-Trousseau)
- 20% die by age 2 from heart and bleeding problems
- Developmental delay with mild to severe mental retardation
- OCD, ADHD, short attention span
- Facial
- Macrocephaly, trigonalcephaly
- Low set ears
- Hypertelorism, ptosis, epicanthal folds, strabismus, coloboma
- Broad nasal bridge, thin philtrum, micorgnathia, downturned mouth
What genes are associated with Jervell and Lange-Nielson syndrome and how is it inherited?
KCNQ1 and KCNE1
Autosomal recessive
Homozygous form of long QT syndrome
What are the features of Jervell and Lange-Nielson syndrome?
Risk of sudden death
Congenital sensorineural hearing loss
Fainting
Both parents have long QT syndrome
What features are associated with Leber Congenital Amaurosis?
Congenial severe vision loss
nystagmus
Group of disease, lots of genes
How is Leber Hereditary Optic Neuropathy inherited and who is affected?
Mitochondrial inheritance
heteroplasmy may affect phenotype
5:1 male:females affected
What are the features of Leber Hereditary Optic Neuropathy?
- Bilateral, painless, subacute visual failure
- First color vision profoundly affected (especially red/green)
- Then develops to blurred central vision, loss of central vision (peripheral vision spared)
- Most have isolated optic neuropathy, some have systemic neuropathy
- Tremors, myopathy, ovement disorders
- Cardiac arrhythmias
- Rapid optic nerve death
- Onset late teens to early 30s, women develop later and may have an MS-like phenotype
What gene is associated with Legius syndrome and how is it inherited?
SPRED1 gene
autosomal dominant
What are the features of Legius syndrome?
- Isolated cafe-au-lait spots
- important to differentiate from NF1 because screening is not needed
- freckling
- macrocephaly
- intellectual disability
What cancers are associated with Li-Fraumeni syndrome?
Cancers
- Early onset bone sarcoma (except Ewing)
- Early onset soft tissue sarcoma
- Osteosarcoma
- Early onset breast cancer
- Adrenocortical carcinoma (50-80% of these are TP53)
- Choroid plexus carcinoma (36-100% of these are TP53)
- Rhabdomyosarcoma <3 years (~25% of these are TP53)
- Brain tumors
- Multiple primary tumors, especially with radiation
- 70% risk for males, 100% for females
What should you test for if you see adrenocortical carcinoma?
TP53/Li-Fraumeni
50-80% of these are due to TP53 mutations
What should you test for if you see choroid plexus carcinoma?
TP53/Li-Fraumeni
36-100% of these are due to TP53 mutations
What gene should you think about when you see rhabdomyosarcoma?
TP53/Li-Fraumeni
~25% of these are due to a TP53 mutation
What is the Classic criteri for Li-Fraumeni syndrome?
- Proband <45 with sarcoma AND
- FDR <45 with any cancer AND
- 3rd family member who is FDR or SDR <45 with cancer, or sarcoma at any age
What are the Li-Fraumeni testing criteria and how likely are you to find a TP53 mutation?
- Proband with any childhood cancer, or sarcoma, brain tumor, or adrenocortical tumor <45 AND
- FDR or SDR with LFS cancer at any age AND
- another FDR or SDR with any cancer <60
20% chance of having a TP53 mutation if meet this criteria
How are Limb-Girddle Muscular Dytrophy Type 1 (LGMD1) disorders inherited?
Autosomal Dominant
How are Limg-Girddle Musculary Dystrophy Type 2 (LGMD2) disorders inherited?
Autosomal recessive
What are the features of limb-girddle muscular dystrophies?
- Affect the voluntary proximal muscles of the shoulder, hips, thighs, and top part of the arm
- Waddling gait
- Difficulty running, standing, climbing stairs. Fall frequently
- Trouble raising and holding arms above head and carrying objects
- Scapular winging, lordosis, scoliosis, contractures, calf hypertrophy
- Cardiomyopathy or arrhythmia
- Difficulty breathing
What can you do to test for a limb-girddle muscular dystrophy?
CK levels are elevated
Muscle biopsy
EMG
Genetic testing with a panel
What gene is associated with Marfan syndrome and how is it inherited?
FBN1 gene (gain-of function mutation leads to decreased myofibrils, nonsense mutations lead to haploinsufficiency)
Autosomal dominant
What features are associated with Marfan syndrome?
Features
- Tall stature
- Decreased upper segment/lower segment ratio
- Arm span exceeds height
- Dolichocephaly (long back of head)
- Long, slender, curved fingers
- Pectus carinatum/excavatum
- Malar hypoplasia (flat cheeks)
- Retinal detachment
- Lens sublaxation or dislocation (ectopia lentis)
- High myopia
- Megalocornia
- Long, spider fingers
- Scoliosis
- Flat feet
- Pneumothorax
- Striae not associated with marked weight change
- Family hx of sudden death
- Heart defects
- Aortic aneurysm, aortic root dilation–>sudden death
What are the features of a baby born to a mom with uncontrolled PKU?
Microcephaly
mental retardation
congenital heart disease
light colored hair
What gene is associated with McCune Albright syndrome and how is it inherited?
GNAS gene (activating mutation)
Always somatic mosaicism, never inherited (don’t do genetic testing)
What are the features of McCune Albright syndrome?
Features
- Polyostotic fibrous dysplasia (scar-like tissue in bones leading to uneven growth & fractures)
- Age 3-10
- Facial-painless lumps, asymmetry, loss of vision/hearing rare
- Skeletal-limping, pain, fractures
- scoliosis
- Café-au-lait like spots
- Irregular borders (coast of Maine), not smooth, defined borders
- First sign
- Early puberty in girls
- Thyroid lesions/disease (hyperthyroid)
- Hypophosphatemia (severe skeletal involvement, fractures, bone pain)
- Excess growth hormone
- Neonatal Cushings syndrome-rare
- Can also have malignancies, polyps, and cardiac involvement
What gene is associated with Megalencephaly-Capillary Malformation Syndrome (MCAP), and how is it inherited?
PIK3CA gene
Heterozygous somatic mutations
- test skin, saliva, or affected tissue
De novo
What kind of disorder is Megalencephaly-Capillary Malformation Syndrome (MCAP)?
Brain overgrowth syndrome
What are the features of Megalencephaly-Capillary Malformation Syndrome (MCAP)?
Features
-
Congenital or early post-natal megalencephaly
- Can have ventriculomegaly and hydrocephaly, cortical brain malformation and polymicrogyria
- Segmental or generalized overgrowhth
- Midline facial capillary malformation
- Hypotonia
- Intellectual disability
- Autistic features
- Epilepsy
- Cutaneous syndactyly
- Coarse facial features with frontal bossing
- Heart defects (VSD, ASD)
- GI problems
- Tumors
What gene is associated with Menkes disease and how is it inherited?
ATP7A gene
X-linked recessive
What causes Menkes syndrome?
Copper deficiency
- copper doesn’t get absorbed correctly from the intestine
- Copper builds up in some tissues (small intestine & kidneys)
- Low copper levels in brain and other tissues
What are the features of Menkes syndrome?
Features
- Hypotonia
- Kinky, brittle hair
- Fragile skin, skin laxity
- Hypopigmented skin
- Umbilical or inguinal hernia
- Pectus excavatum
- Temperatures instability
- hypoglycemia
- Occipital horn in skull
- Seizures
- Failure to thrive
- Neurodevelopmental delay & neurologic issues
- Gastric polyps
- Wormian bone
- osteoporosis
How is Menkes syndrome treated and what is the prognosis?
Treat with copper injections
Usually die around 9 months
What gene is associated with myotonia congenita and how is it inherited?
CLCN1 gene
Can be dominant (Thomsen myotonia congenita)
Can be recessive (Becker myotonia congenita)
What are the features of Myotonia congenita?
- Warm-up phenomenon
- onset childhood to young adulthood
- Myotonia (delayed muscle relaxation)
What kind of disorder is myotonia congenita and how can you test to look for it?
Channelopathy
Abnormal short exercise test (repeated drops and rises because of warm-up phenomenon)
Normal long exercise test
What gene is associated with myotonic dystrophy type 1 and how is it inherited?
DMPK gene
Autosomal dominant with anticipation
CTG Triplett repeat expansion
- 35-49 repeats-asymptomatic premutation
- 50-~150 repeats-mild presentation
- ~100-~1000 repeats-classic presentation
- >1000 repeats-congenital myotonic dystrophy
Expands through the mother
What are the features of myotonic dystrophy?
- Myotonia
- gait disturbance, weakness
- Cataracts with Christmas tree appearance
- Frontal balding, Ptosis and myotonic mouth
- Arrhythmia, cardiomyopathy (cause of death)
- Anxiety/depression, Hypersomnia, sleep apnea
- Minor cognitive delay
- Thyroid dysfunction
- Diabetes
- Testicular atrophy, gynecomastia, infertility
- Constipation
- Difficulty swallowing, dysphagia
- Onset typically 20s-30s,
- Death typically 48-55 years
- Due to respiratory difficulty and/or cardiac disease
How is Nemaline Myopathy inherited?
Autosomal dominant and autosomal recessive
de novo
9 genes
one gene common in Amish communities
What are the features of Nemaline myopathy?
Severe congenital, congenital, and childhood-onset forms
- Severe congenital form is often lethal, severe hypotonia, GER, respiratory insufficiency
- Amish form is lethal in early childhood, hypotonia, contractures, tremors, pectus carinatum, muscle atrtophy
- Intermediate congenital form has contractures, weakness, need for wheelchair & ventilator support by 11
- Typical congenital has hypotonia, feeding difficulties, delayed motor milestones, waddling gait, bulbar and proximal weakness, nocturnal hypoventilation, recurrent infections, slow/static progressive weakness
- Childhood onset 1st-2nd decade onset, foot drop, muscle slowness, slowly progressive
- Adult onset 20-50 years, myalgia, cardiomyopathy, head drop, rapid progression
- CK levels normal to mildly elevated
- Muscle biopsy shows nemaline rods with Gomori tricome stain
What gene is associated with Neurofibromatosis 1 and how is it inherited?
NF1 gene
Autosomal dominant
50% de novo
What is NF1 diagnostic criteria?
Diagnosis (2 of the the following) is highly specific (~50% meet by age 1 without family hx)
- Skin lesions
- Café-au-lait spots
- ≥6 lesions over 5 mm when pre-pubertal, over 15mm if post-pubertal
- Tend to grow and get bigger with the child
- ≥6 lesions over 5 mm when pre-pubertal, over 15mm if post-pubertal
- Plexiform neurofibromas
- Tend to be invasive
- Can be hard or soft
- Earlier onset
- ≥2 neurofibromas
- Can be internal and never seen
- Post-pubertal onset
- Axilla and/or inguinal skin freckling
- Café-au-lait spots
- Eye findings
- Lisch nodules
- In 90% of patients over age of 6
- Iris hamartomas, don’t affect vision
- Optic nerve glioma
- Develop before age 6
- 3% become malignant, but can also spontaneously regress
- May not affect vision, but can lead to blindness
- Lisch nodules
- Family history of NF1
- Skeletal Features
- Sphenoid wing dysplasia (bone pushes eye out)
- Usually unilateral
- Pseudo-arthrosis bowing
- Almost like a second joint that causes bowing in the leg or arm
- These bones tend to be fragile and fracture
- Sphenoid wing dysplasia (bone pushes eye out)
What NF1 features are present in infancy or preschool?
Plexiform neurofibroma
tibial dysplasia
cafe-au-lait
developmental delay (mainly speech)
What NF1 features are present in school age children?
Optic glioma (by age 6)
lisch nodules
short stature
hypertension
cafe-au-lait
What NF1 features are present in adolescence?
Dermal neurofibroma
scoliosis
hypertensin
cafe-au-lait
What NF1 features are present in adulthood?
Neurofibromas
Cafe-au-lait
Breast, thyroid, colon cancer (low risk)
Hypertension
What gene is associated with neurofibromatosis 2 and how is it inherited?
NF2 gene
Autosomal dominant
- 1/3 somatic mosaicism
What are the features of NF2?
Hearing loss
- from bilateral vestibular schwannoma
- can be presenting feature
High risk for tumors
- bilateral vestibular schwannoma
- schwannomas of other cranial and peripheral nerves (60%)
- meningiomas (50%)
- Ependymomas (rare)
- Astrocytomas (rare)
Facial nerve palsy or other single nerve disorder compromise
What kind of disorder is Noonan syndrome?
Rasopathy
What features are associated with Noonan syndrome?
Cafe-au-lait spots
congenital heart defects (PVS, PDA, hypertrophic cardiomyopathy)
Mild intellectual disability
coarse facial features
short stature
webbing of the neck with low hairline
How is Oculocutaneous albinism inherited?
Autosomal recessive
4 genes (TYR, OCA2, TYRP1, SLC45A2)
What features are associated with oculocutaneous albinism?
General features
- Hypopigmentation of hair, skin, iris (blue)
- can see choroidal blood vessels in eyes
- Infantile nystagmus, strabismus
- Reduced visual acuity (from foveal hypoplasia)
- With sun exposure
- Rough/thickened skin (pachydermia)
- Premalignant lesions (solar keratosis) and skin cancer
- 4 different types with varying severity
What types of genes are associated with Osteogenesis Imperfeca and how is it inherited?
Collagen gene
Autosomal dominant
What are the features of Osteogenesis imperfecta?
- Fractures
- Conductive hearing loss in adulthood
- because the middle ear bones break
- Norma to short stature
- joint hypermobility
- dentinogenesis imperfecta (yellow, translucent teeth)
What gene is associated with paramyotonia congenita and how is it inherited?
SCN4A gene
Autosomal dominant
What are the features of paramyotonia congenita?
Myotonia
worse in the cold, stiff in the cold
What kind of disorder in paramyotonia congenita and what tests can be done to test for it?
Channelopathy
Abnormal short exercise test
- immediate drop that stays low
Normal long exercise test
How is Parkinson disease inherited?
Idiopathic
Autosomal dominant
Autosomal recessive
X-linked
What features are associated with Parkinson disease?
Resting tremor
muscle rigidity
Bradykinesia (slow movement)
shuffling gait and/or postural instability
depression, halluciations, dementia
Can lose sense of smell
What genes are associated with Pendred syndrome and how is it inherited?
Mostly SCL26A4 gene, but can be FOX11 or KCNJ10
- can be digenic
- 48% have no mutation found
Autosomal recessive
What features are associated with Pendred syndrome?
Congenital sensorineural hearing loss
- enlarged or dilated vestibular aqueduct
- Think Pendred if you see this
- Mondini malformation possible
Thyroid goiters in early pubery to adulthood
What features are associated with Pierre-Robin sequence?
Mandibular hypoplasia
U-Shaped cleft palate
big tongue
obstructive apnea (from tongue)
feeding difficulties
What syndromes are associated with Pierre-Robein sequence?
Stickler
22q11 deletion
Treacher-Collins
Compomelic dysplasia
What features are associated with Posterial Orthostatic Tachycardia (POTS)?
Dizziness
trouble standing up (because of blood vessel problems)
Tachyarrhythmias
(Treat with fluids and salts)
What are the genetic causes of Prader-Willi syndrome?
Loss/alteration to the paternal copy of 15q11.2-q13
- 70% from paternal deletion
- Maternal UPD
- Imprinting center defect (recurrence 50%)
Do methylation testing of SNRPN
What features are associated with Prader-Willi syndrome?
Features
- Severe hypotonia and feeding difficulties, FTT as an infant
- Excessive eating & morbid obesity in early childhood
- Global developmental delay, most need lifetime support and supervision
- Temper tantrums, manipulative behavior, stubborn, OCD
- Infertility, hypogonadism
- Short stature, small feet and hands
- Hypopigmentation of skin, eyes, and hair
- Sleep abnormalities (daytime sleepiness)
- Scoliosis, strabismus
- Almond shaped eyes, thin upper lip, down-turned mouth, narrow nasal bridge
What are the features of progressive familial intrahepatic cholestasis (PFIC)?
Liver problems
- cholestasis (high direct bilirubin)
- liver cancer
- liver disease and failure
- May been liver transplant
Itching
Growth failure
Pancrease, intestine, and lung problems
What gene is associated with Psychosis, Pyrimidal Signs, and Macroorchism (PPM-X) and how is it inherited?
MECP2 gene
X-linked
What are the features of Psychosis, Pyramidal Signs, and Macroorchism (PPM-X)?
Males
- severe but not lethal
- intellectual disability
- resting tremor
- ataxia
- enlarged testes
Carrier females have milder symptoms
What cancers are associated with Cowden syndrome?
- Cowden syndrome-increased cancer risk
- Thyroid cancer
- Even in kids, get baseline ultrasound at age 5
- Breast cancer
- Uterine cancer
- Other cancers
- GI polyps, bleeding risk
- Begin cancer screening at age 18
- Thyroid cancer
What features are associated with Bannayan-Riley-Ruvalcaba syndrome (PTEN mutations)?
BRRS
- Macrocephaly
- Big baby at birth, normal height as adult
- hypotonia
- Mild intellectual developmental delay
- Hamartomas
- Speckled penis
- Autism
- 5-10% of children with macrocephaly and an autism spectrum disorder have a PTEN mutation
- Intestinal polyposis (hamartomas)
- Lipomas, hemangiomas
- May have same cancer risks as Cowden syndrome
- Screen for thyroid nodules
How is Refsum disease inherited?
Autosomal recessive
What are the features of Refsum disease?
Severe progressive sensorineural hearing loss
retinitis pigmentosa
anosmia
How can Refsum disease be treated?
Dietary restriction of phytanic acid
high calorie diet
plasmaphoresis for cardiac arrhythmias or extremem weakness
What gene is associated with retinoblastoma and how is it inherited?
RB1 gene
Autosomal dominant
- 80% de novo, usually no family history
- still test sibs in case germline mosaicism
- If unilateral and no family history, 1 in 7 have a mutation
Test tumor tissue first if possible in case it is due to somatic mosaicism
What cancers are associated with germline RB1 mutations?
Retinoblastoma
osteosarcoma
soft tissue sarcoma
brain tumors
nasal cavity tumors
What gene is associated with Rett syndrome and how is it inherited?
MECP2 gene (loss of function mutation)
do deletin analysis
X-linked dominant
De novo mostly
lethal in males
What surveillance do you do for RB1 mutations?
Eye exam every 3-4 weeks until age 1, then less frequently until age 3
Be aware of and evaluate bone pain or lumps for sarcoma risk
Unsure if this extra screening needs to be done for somatic mosaicism
What are the features of Rett syndrome?
Features
- Regression around 6 mos-1.5 years
- Mental retardation
- Language and learning disabilitys
- Hand wringing
- Lose the ability to walk
- Parkinsonian-like symptoms
Neurodegenerative disorder
What are the features of atypical Rett syndrome and what gene is it associated with?
Later regression than Rett
Similar to unconfirmed Angelman but with regression
Females can ahve few or no symptoms due to skewed X-inactivation
Can have just mild learning disabilities and neurological manifestations
MECP2 gene
What are the features of ROHHAD?
Rapid onset obesity
Hypothalmic dysfunction
Hypoventilation and respiratory manifestations
Autonomic dysregulation
Behavior disorders
(very rare)
What are the genetic causes of sickle cell disease and how is it inherited?
HbS variant (on beta-globin gene HBB) + another beta-globin gene mutation (SS, SC, SB+, SB0)
Autosomal recessive
What is the sickle cell mutation and what is the carrier frequency?
HBB gene
Glu6Val
1 in 12 African Americans are carriers
1 in 625 Caucasians are carriers
What are the features of sickle cell SS disease?
Features
- anemia
- Pallor
- Delayed growth and puberty
- Pain crises
- Jaundice
- Hand-foot syndrome (can’t bend hands & feet b/c of trapped RBCs)
- Stroke
- Acute chest syndrome (like pneumonia)
- Fever, chest pain, hypoxia, and other respiratory symptoms
- More common in kids, but can occur at any age
- Most common cause of acute death in adults
- Often follow vaso-occlusive crisis
- General weakness
- Priapism (erection won’t go away b/c of trapped RBCs)
- Gallstones
- Pulmonary hypertension
- Chronic sores/ulcers on legs
- Spleen dysfunction (splenomegaly) from sequestration and infarction
- Infections (spleen fights infections)
- Neurologic
- Stroke, silent cerebral infarcts, cerebral hemorrhage, Moyamoya disease
What treatment and management is done for sickle cell disease?
- Prophylactic penicillin in children
- illness can lead to an anemic crisis
- prompt follow-up with fevers
- risk for anemia
- hydration
- avoidance of climate extremes and extreme fatigue
- Hydroxyurea
- upregulates gamma chain production and fetal hemoglobin
- bone marrow translplant for severe cases
What are the most common causes of mortality in sickle cell disease?
In children
- Infection
- Splenic sequestration crises
In adults
- Chronic end-organ dysfunction
- Thrombosis
- Treatment-related complications
Average lifespan 42y for males, 48 y for females
What gene is associated with Simpson-Golabi-Behmel syndrome and how is it inherited?
GPC3 gene
X-linked
What are the features of Simpson-Golabi-Behmel syndrome?
Overgrowth
mental retardation
dysmorphic features
hepatoblastoma risk
What cancers are associated with SMARCB1 mutations?
Atypical/Tertoid rhabdoid tumor (AT/RT) (CNS rhabdoid)
Rhabdoid (can be in kidney or soft tissue
Schwanomatosis (multiple schwanomas)
What are the genetic causes for SMARCB1 cancer risks?
Gonadal mosaicism common
Can be deleted with 22q11 deletion syndrome
What should you think of when you see an Atypical/Teratoid rhabdoid tumor (AT/RT)?
SMARCB1
~35% of AT/RT are due to SMARCB1 mutations
What should you think of when you see a rhabdoid tumor?
SMARCB1
~25% of rhabdoid tumors are due to SMARCB1
What is the current screening for SMARCB1 mutations?
Baseline CNS MRI
renal ultrasound
What gene is associated with Smith-Lemli-Opitz syndrome, what is the etiology, and how is it inherited?
DHCR7 gene
autosomal recessive
Cholesterol biosynthesis problem (high 7-DHC levels because it can’t be converted to cholesterol)
What are the features of Smith-Lemli-Opitz syndrome?
Features
- 2,3 toe syndactyly
- Cleft palate
- Cataracts
- Intellectual disability
- Hearing loss
- Renal anomalies
- Liver disease
- GI problems (Pyloric stenosis, Hirschprungs)
- Sex reversal in males
- Microcephaly & midline defects (Dandy-Walker malformation, Holoprosencephaly)
- Facial
- Ptosis, Epicanthal folds, Downward slanting palpebral fissures
- Small upturned nose
- Micrognathia & High arches palate
- Congenital heart defects (AVSD, ASD)
- Abnormal Behavior
- Sleep cycle disturbance
- Self-injury
- Autism behaviors (50% risk for autism spectrum disorder)
- Depression
- Hyperreactivity and temper dysregulation
What does a quad screen for Smith-Lemli-Opitz look like?
Low uE3, HCG, and AFP
How do you treat Smith-Lemli-Opitz syndrome and how effective is it?
Treat with cholesterol supplementation
Not super effective
What are the genetic causes of Smith-Magenis syndrome and how is it inherited?
17p11.2 deletion
RAI1 is the critical gene
can also be RAI1 mutations
De novo
What are the features of Smith-Magenis syndrome?
Features
- Hypotonia, FTT, feeding difficulties
- Infrequent crying as babies
- Disrupted sleep pattern from abnormal circadian rhythm
- Mild-moderate intellectual disability and developmental delay, significant expressive language deficit
- Ocular abnormalities
- Abnormal gait
- Hearing loss or issues
- Constipation
- Hoarse voice and laryngeal anomalies
- Self-injurious behavior and other behavioral problems
- “Self hug”
- scoliosis
- short stature
- small hands and feet
- Facial
- tent shaped upper lip
- upslanting palpebral fissures
- hypopigmentation with rosy cheeks
- synophrys
What kind of disorder is Sodium Channel Myotonia?
Channelopathy
What are the features of sodium channel myotonia?
Grip myotonia
electrical myotonia
episodic weakness
muscle pain
symptomatic eyelid myotonia
normal short and long exercise tests
What are the genetic causes of Spinal Muscle Atrophy (SMA)?
SMN1 gene
- majority due to a homozygous deletion of exon 7
- some compound heterozygotes of an exon 7 deletion and an intragenic mutation
SMN2 can provide a better outcome
- the more copies of SMN2 you have, the milder the phenotype
What are the features of spinal muscle atrophy (SMA) and what is the prognosis?
Severe muscle weakness
- In the severe form (Type 1-most common), they may never sit on their own
- In the least severe forms (Type 3 and Type 4), they may be able to walk or just have mild proximal muscle weakness
Respiratory and bulbar muscle weakness with swallow dysfunction
- may need a G-tube
- leads to aspiration and pneumonia
- Usually die <2 years due to respiratory and swallowing issues
Develop REM sleep disordered breathing and eventually NREM sleep disordered breathing
With the less severe forms, may have tremors, contractures, kyphoscoliosis, obesity, scoliosis
What gene is associated with spinocerebellar ataxia and how is it inherited?
ATXN gene
Autosomal dominant with anticipation
Trinucleotide repeat
- CAG repeats with effect from interrupting CAT repeats
- 6-44 CAG repeats is normal
- 36-44 repeat pathogenicity depends on CAT size
- If no CAT interruptions, you are asymptomatic but can expand into pathogenic range for children
- 39-44 repeats without CAT interruptions can be symptomatic, but if interrupted may be asymptomatic
- >44 repeats is pathogenic
What are the features of spinocerebellar ataxia?
Features
- Progressive cerebellar ataxia
- Chorea, distal muscle weakness, peripheral neuropathy, gait disturbance
- Deterioration of bulbar functions
- Dysarthria, dysphagia
- Other
- Nystagmus, optic atrophy, brisk deep tendon reflexes, hypotonia
Supportive care only
- Onset to death 10-30 years
What genes are associated with Stargardt disease and how is it inherited?
ABCA4 gene, autosomal recessive
EVOLVL4 gene, autosomal dominant
What are the features of Stargardt Disease
Eye problems with a heterogeneous presentation (60% present <40 years)
- Hereditary macular dystrophy
- progressive worsening of visual acuity
- retinitis pigmentosa
What gene is associated with Stickler syndrome and how is it inherited?
COL2A1 gene
Autosomal dominant
What are the features of Stickler syndrome?
Features
- Myopia from birth–>thick glasses
- Retinal detachment
- Mitral valve prolapse
- Hypermobile joints
- Progressive sensorioneural hearing loss
- Later develop spondyloepiphyseal dysplasia
- Leads to arthritis
- Mild short stature
- Narrowed joint spaces on x-ray
-
Abnormalities of the vitreous gel architecture (ocular finding)
- Pathognomonic
- Facial features
- Flat midface
- Depressed nasal bridge with short nose
- Anteverted nares
- Micrognathia
- U-shaped cleft palate from Pierre Robin sequence
Can be confused with Marfan
What are some things you should ask about when you suspect Stickler syndrome?
Early arthritis (from spondyloepiphyseal dysplasia)
Retinal detachment
Cleft palate
Hearing loss
What is the inheritance of strabismus?
Multifactorial and complex Mendelian genetics
Strong familial component for syndromic and non-syndromic forms
What is the recurrence risk to sibs for strabismus?
20-30% if the parents are not affected
30-50% if a parent is affected
What is the risk for strabismus in a FDR and a SDR of an affected person?
16-50% recurrence risk for FDR
~8% risk for SDR
What gene is associated with Sturge-Weber syndrome and how is it inherited?
GNAQ gene (548G>A)
- Activation of the ERK pathway
Not seen familialy!
- 1-18% are somatic mosaics
What are the features of Sturge-Weber?
Vascular problems
- Port-wine stains on face
- seizures
- mental retardation
Glaucoma
Calcifications to the cortex
What do problems with surfactant protein C cause?
Interstitial Lung Disease
- misfolded surfactant protein C accumulates in the alveolar type II cells and results in cell injury and apoptosis
What is the prevalence of Factor V Leiden?
3-5% of Caucasians are heterozygous
1 in 400 caucuasians are homozygous
12-20% of unselected venous thrombosis patients have a Factor V Leiden mutation
What factors play a role in clot formation?
Virchow’s Triad
- Changes in the vessel wall
- Changes in blood composition
- Changes in blood flow
Environment
- oral contraceptives, hormone replacement therapy
- pregnancy
- weight, diet
Genetics
What are the symptoms of thrombosis?
Pain, tender to the touch
tight
swelling
redness
Should you test for thrombophilia conditions?
It’s not really recommended
- Knowing about a genetic mutation will not change management
But testing might increase awareness
Do an individual assessment to decide to test or not
What risks are associated with Prothrombin mutations?
2-3 fold increased risk for thrombotic event
slightly increased risk for arterial clots (stroke, heart attack)
Associated wtih pregnancy loss and pregnancy complications
What is the prothrombin mutation associated with an increased risk for a thrombotic event?
Prothrombin G20210A
What is a homozygous deficiencty of Protein C or Protein S associated with?
Neonatal purpura fulminans
Severe
What risks are associated with Protein C and S deficiencies?
2-10 fold increased risk for thrombosis (5-10% lifetime risk)
- Rate of recurrence slightly increased
Mild assosication with stroke and heart attack, especially in young
Associated with pregnancy loss (especially late)
Treat with human plasma-derived protein C concentrate
What risks are associated with Antithrombin II deficiency?
50% lifetime risk to clot
- VTE risk is 10-17% per year
Weak association with MI/stroke
Slightly higher risk of fetal loss
Homozygous is lethal
Heterozygous is rare
What gene is associated with Treacher-Collins syndrome and how is it inherited?
TCOF1 gene
Autosomal dominant
60% de novo
What are the features of Treacher-Collins syndrome?
Underdevelopment of bone in the face and jaw
- very dysmorphic
- downslanting palpebral fissures
Conductive hearing loss because of external ear abnormalities
Coloboma of the lower eyelid
Pierre-Robin sequence
What genes are associated with tuberous sclerosis and how is it inherited?
TSC1 and TSC2
Autosomal dominant
2/3 de novo
What are the features of tuberous sclerosis?
Very variable, may not be affected at all
Skin
- Ash leaf spots/hypopigmented spots
- Shagreen patch (looks like rash)
- Facial angiofibroma (looks like acne)
- Ungual fibroma (fibroma under the nail)
Kidney issues
- Can be associated with polycystic kidney disease (TSC2)
- Benign angiomyolipoma (huge mass on kidney, cysts)
Brain issues
- Subependymal glial nodules
- Cortical/subcortical tubers
- 70%
- Correlated with seizures
Cardiac rhabdomyoma
- Infants and fetuses only
- Typically goes away and is benign
Dental pits
Lymphangioleiomyomatosis (large growth in the lung)
- Famales only
Seizures
Developmental delays
Headaches
What disorder should you think of when you see a cardiac rhabdomyoma?
Tuberous sclerosis
How is tuberous sclerosis managed?
Management
- MRI 1-3 years
- Seizure management with meds, removal of tubers, electroencephalography
- Electrocardiogram & ECG if heart problesm
- Renal u/s
- Ophthalmology exam
- Neurodevelopmental & behavioral evaluation
- Chest CT for adult females (for LAMs)
What is the genetic cause of Turnder syndrome?
XO genotype
- 50% mosaic
- If are mosaic XY, have a 12% risk for gonadoblastoma
What are the features of Turner syndrome?
Features
- Short stature
- Phenotypic female
- Infertility/don’t undergo puberty/premature ovarian failure
- Webbed neck
- Low posterior hairline
- Lymphedema of hands and feet
- Skeletal abnormalities
- Kidney issues
- Heart defects (aortic coarctation)
- Variable developmental delay and behavior problems
What kind of disorder is Pompe disease?
Glycogen storage disorder (Type II)
and a lysosomal storage disorder
What gene is associated with Pompe disease and how is it inherited?
GAA gene
Autosomal recessive
What are the features of Pompe disease?
Features
- Muscle weakness
- Cardiomyopathy
- Delays
- Failure to thrive
- Respiratory distress
- Early death (if infantile presentation)
How is Pompe disease treated and what does it improve?
ERT available
- Increases lifespan
- Improves myocardial function
- Improves skeletal muscle function
- Improves motor abilities & walking abilities (from improving muscle function)
- Helps with sleep disordered breathing and lung function
- Improves quality of life
How is Usher syndrome inherited?
Autosomale recessive
What are the features of Usher syndrome?
Sensorineural hearing loss
- Mostly congenital
- May not develop speech without cochlear implant
Retinitis Pigmentosa
- Progressive vision loss
- Onset usually in 1st to 2nd decade of life
How does retinitis pigmentosa present?
Loss of night vision
Loss of peripheral vision
–>tunnel vision
What causes VACTERL?
Inheritance unknown
Multigene and environement association
Associated with maternal diabetes
What is the recurrence risk for VACTERL?
2-3%
What are the features of VACTERL?
Features (at least 3+ of the following)
-
Vertebral abnormalities
- hypoplastic/malformed vertebrae & ribs, scoliosis, sacral agenesis
-
Anal atresia
- can’t poop, passageway not there
-
Cardiac defect
- VSD mostly, can be ASD, tetralogy of fallot, CHF, hypoplastic left heart, truncus arteriosus
-
Tracheo-Esophageal fistula and/or esophageal atresia
- leads to aspiriation, respiratory infections, FTT
-
Renal abnormalities
- renal aplasia, dysplasia, hydronephrosis etc
-
Limb anomalies
- radial aplasia/hypoplasia, absent/displaced thumb, poly/syndactyly, clubfoot
What gene is associated with Von Hippel-Lindau disease and how is it inherited?
VHL gene
Autosomal dominant
What is associated with VHL Type 1?
- Retinal hemangioblastoma
- CNS hemangioblastoma
- Clear cell renal cell carcinoma
- Pancreatic neoplasms & cysts
- Deletion/truncating mutation
What is associated with VHL Type 2?
Type 2A
- Pheo
- Retinal hemangioblastomas
- CNS hemangioblastomas
Type 2B
- Pheo
- Retinal hemangioblastomas
- Clear cell renal cell carcinoma
- Pancreatic neoplasm cysts
Type 2C
- Pheos only
What risk is associated with Von Willebrand disease and what are the symptoms?
Bleeding tendency (milder than hemophilia)
Symptoms
- Menorrhagia
- Epistaxis
- Bleeding at dental extraction or with minor injury
- Ecchymoses
- Post-operative hemorrhage
What type of Von Willebrand disease is most common?
Type 1 (75%)
What kind of defect is Type 1 Von Willebrand disease?
Quantitative defect of Von Willebrand factor (not enough factor made)
How is Von Willebrand disease inherited?
Mostly autosomal dominant except for Type 2N and Type 3 (autosomal recessive)
What are the features of Von Willebrand disease Type 1?
Mild to moderate mucocutaneous bleeding
reduced Factor VIII (because they bind togeher)
What kind of defect is Type 2 Von Willebrand disease?
Qualitative problem of Von Willebrand factor (can’t function or bind as it should)
What type of Von Willebrand disease mimics hemophilia A and how is it inherited?
Von Willebrand disease Type 2N
autosomal recessive
Excessive bleeding with surgery
What are the features of Type 3 Von Willebrand disease and how is it inherited?
Hemophilia phenotype
- severe, recurrent, spontaneous mucocutaneous and musculoskeletal bleeing
Autosomal recessive
- homozygous form of Type 1 Von Willebrand disease
- No Von WIllebrand factor is made
May develop Von Willebrand Factor inhibitors
How is Waardenburg syndrome inherited?
Autosomal dominant mostly
some autosomal recessive
What are the features of Waardenburg syndrome?
Sensorineural hearing loss (variable degree)
White forelock
Heterochromia irides
Dystopia canthorum (wide spaced eyes)
Hirschprung disease
What is the genetic cause of WAGR syndrome?
Deletion of WT1 and PAX6
What are the features of WAGR syndrome?
Wilms tumor
Aniridia
Genitourinary abnormality
mental Retardation
What gene is associated with Wilson’s disease and how is it inherited?
ATP7B gene
Autosomal recessive
What is the cause/etiology of Wilson’s disease?
Copper accumulation in the eyes, brain, and kidneys
Low serum copper, higher urine copper
What are the features of Wilson’s disease?
- Acute or chronic liver failure
- Neurologic disease
- due to copper accumulation in the brain
- change in school performance or behavior
- Kayser-Fleischer rings
- due to copper accumulation in the eyes
What should be done for the family when someone is diagnosed with Wilson’s disease?
Screen all FDR for Wilson’s disease (urine and serum test, look for Kaiser-Fleischer rings)
What is the treatment for Wilson’s disease?
Chelation to try to prevent the accumulation of copper
What is the genetic cause of Wolf-Hirschhorn syndrome and how is it inherited?
4p16.3 deletion
85-90% de novo
What is the female:male ratio for Wolf-Hirschhorn syndrome?
2:1 female:male
What are the features of Wolf-Hirschhorn syndrome?
Features
- “Greek warrior helmet” face, hypertelorism, microcephaly, asymmetry
- Poorly formed ears
- Hearing loss
- Pits or skin tags
- Intellectual disability mild to severe
- Developmental delays
- Poor motor and verbal skills
- Hypotonia, feeding difficulties
- IUGR and postnatal growth retardation
- Febrile seizures
- Hemangiomas (red spots)
- Marble/dry skin
- Skeletal anomalies
- Scoliosis, short stature
- Congenital heart defect
- Antibody deficiency
What is the prognosis for Wolf-Hirschhorn syndrome?
May be stillborn
35% die within first 2 years
Can live into 20s-40s
What type of genes are associated with Zellweger syndrome and how is it inherited?
Genes that make up the peroxisome
Autosomal recessive
What is the cause/etilogy of Zellweger syndrome?
Defect with perosisomal metabolism
- Leads to the accumulation of very long fatty acids and branched chain fatty acids, and a deficiency of plasmoalogens
What are the features of Zellweger syndrome?
Features
- Hypotonia, poor feeding
- Seizures
- Apnea
- Hepatomegaly and/or renal cysts
- Vision problems
- Chondrodysplasis punctata
- Brain issues
- Impaired neuronal migration and positioning
- Demyelination of CNS (cerebral neurons)
- Reduced brain development
- Progressive vision and hearing loss
- Profound developmental delay/intellectual disability
- Facial
- High forehead
- Hypoplastic supraorbital ridges
- Epicanthal folds
- Midface hypoplasia
- Heart defects (VSD, ASD)
- Eventually respiratory distress, GI bleeding, and liver failure
How do you test for Zellweger syndrome?
Start with a biochemical test for very long chain fatty acids, branched chain fatty acids, and plasmalogens
What is the prognosis for Zellweger syndrome?
Survival usually <1 year