Abnormalities & Diseases Flashcards
What is another name for Trisomy 21?
Down Syndrome
What is another name for Trisomy 13?
Patau Syndrome
What is another name for Trisomy 18?
Edwards Syndrome
What is Klinefelter Syndrome?
47, XXY
What is the phenotype of Kinefelter Syndrome?
Tall stature, hypogonadism, gynecomastia, infertile, language impairment
What is the phenotype of 47,XYY Syndrome
Indistinguishable physically or mentally from normal males and are usually fertile; increased risk of behavioral and educational problems, delayed speech and language
What is Turner Syndrome?
45,X
What is the phenotype of Turner Syndrome?
Short stature, webbed neck, edema of hands and feet, broad shield chest, renal/cardio anomalies, failure in ovarian development
What is the event that leads to Velocardiofacial syndrome?
Deletion of a gene on chromosome 22
What is the event that leads to Velocardiofacial syndrome?
Deletion of a gene on chromosome 22
What causes Prader-Willi Syndrome, genetically?
A deletion in the paternal 15q11-13
What causes Angelman Syndrome, genetically?
A deletion in the maternal 15q11-13
Angelman syndrome is caused by defects in the expression of what? What does it do?
UBE3A; encodes a ubiquitin ligase involved in early brain development
Prader-Willi syndrome is caused by defects in the expression of what genes?
SNORD116 snoRNA genes
How can Prader-Willi Syndrome result from uniparental disomy?
If the maternal is disomic fro chromosome 15 and the father has a normal chromosome 15, this results in incompatible with life trisomy 15; but if there’s mitotic disjunction early during development, fetus is rescued but if it has just the remaining two maternal chromosomes, it will have Prader-Willi.
Is Chediak-Higashi Syndrome autosomal recessive or dominant?
Recessive
Chediak-Higashi Syndrome causes problems with what?
Lysosomal trafficking
What is the phenotype of Chediak-Higashi Syndrome?
Partial oculocutaneous albinism, light hair, immunodeficiency, mild-bleeding tendency, variable cognitive impairment, neuropathy, ataxia, and parkinsonism
What is the expressivity of Chediak-Higashi Syndrome?
Variable severity of symptoms with neurological manifestations from childhood to early adulthood
In cancer, does low hypodiploidy indicate a poor or good prognosis?
Poor prognosis
In cancer, does high hypodiploidy indicate a poor or good prognosis?
Good prognosis
Why does high hypodiploidy in cancer indicate a good prognosis?
A gain of chromosomes can mean more GFs –> Tumor Suppressor Genes are not lost
What tests can be used to diagnose Prader-Willi?
FISH or microarray
What specific opthalmologic problems are common in patients with Prader-Willi?
Strabismus & Nystagmus
What is a common treatment for Prader-Willi?
Growth hormone
What is the phenotype of maternally inherited 15q interstitial duplication cause?
Autism, NOT dysmorphic, hypotonic, seizures
What does isodicentric isochromosome 15q (IDIC 15) cause?
Autism, NOT dysmorphic, hypotonic, seizures
What are supernumerary marker chromosomes?
Inverted duplicated isodicentric 15q
How can Angelman Syndrome be diagnosed?
FISH, UPD of 15q, or imprinting errors of 15q detected with methylation studies
What is the phenotype of Angelman Syndrome?
Mildly dysmorphic facial features, hypotonia, spasticity, intellectual disability, seizures, autism
What percentage of all DS cases is due to Trisomy 21?
95%
What percentage of all DS cases is due to an unbalanced translocation between chromosome 21 and another acrocentric chromosome?
3-4%
What percentage of all DS cases is due to mosaic trisomy 21?
1-2%
How can a fetus be tested for DS during the first trimester?
Ultrasound measurement of nuchal folds + beta-hCG + PAPP-A
How can a fetus be tested for DS during the second trimester?
beta-hCG, aFP, unconjugated estriol, and inhibin levels
What are common medical issues associated with DS?
Cardiac, gastrointestinal, opthalmologic, EENT, endocrine, orthopedic, hematologic, developmental, neurologic, psychiatric
Approximately what percentage of patients with DS present with cardiac issues?
50% - atrioventricular canal is common
Approximately what percentage of patients with DS present with structural gastrointestinal anomalies?
10-15% - esophageal atresia, duodenal atresia, Hirschsprung’s
What kind of functional GI issues do many children with DS present with?
Feeding problems, constipation, GERD, Celiac
What kind of opthalmologic problems do many children with DS present with?
Blocked tear ducts, myopia, lazy eye, nystagmus, cataracts
What kind of EENT problems do many children with DS present with?
Chronic ear infections, deafness, chronic nasal congestion, enlarged tonsils and adenoids (obstructive apnea)
What kind of endocrine problems do many children with DS present with?
Hypothyroidism, insulin dependent diabetes, alopecia areata, reduced fertility
What kind of orthopedic problems do many children with DS present with?
Hips, joint subluxation, atlantoaxial subluxation
What kind of hematologic problems do many children with DS present with?
Myeloproliferative disorder, leukemia risk, iron deficiency anemia
What kind of developmental problems do many children with DS present with?
Hypotonia, intellectual disability, speech problems
What kind of neurologic problems do many children with DS present with?
Hypotonia, seizures
What kind of psychiatric problems do many children with DS present with?
Depression, early Alzheimer’s, autism (10%)
What is the karyotype of patients with Turner Syndrome?
45, X
What are some abnormalities of the cardiovascular system in a patient with Turner Syndrome?
Bicuspid aortic valve, coarctation of the aorta, systemic hypertension, prolonged QTc Syndrome, partial anomalous pulmonary venous connection, persistent left SVC
What are some abnormalities of the eye in patients with Turner’s syndrome?
Inner canthal folds, ptosis, blue sclera
What are some abnormalities of the skeletal system in patients with Turner’s syndrome?
Cubitus valgus, short 4th metacarpal, short stature
What are some abnormalities of the neck in patients with Turner’s syndrome?
Webbed neck, low hairline, cystic hygroma
What are some learning abnormalities in patients with Turner’s syndrome?
Math difficulty, visual spatial skills, low non verbal scores
What is the disease classification of PKU (phenylketonuria)?
Autosomal recessive
What are four phenotypes of PKU?
High phenylalanine in blood and phenylalanine metabolites in the urine, hyperactivity and epilepsy, mental retardation and microcephaly
PKU is a defect in what?
PAH (phenylalanine hydroxylase) (>98%) or defects in the PAH cofactor BH4 (tetrahydrobiopterin) (1-2%)
PAH converts what to what?
phenylalanine to tyrosine
How are newborns screened for PKU?
Tandem Mass Spectrometry (MS?MS) which sorts molecules in blood specimen by size, weight, and quantity. Fast detection and high sensitivity.
What is the main treatment of PKU?
Low phenylalanine diet. Other possibilities include BH4 supplementation, neutral amino acid supplementation, ERT, gene therapy.
What population is most at risk for α1-antitrypsin deficiency (ATD)?
people with Northern European ancestry
When is ATD usually diagnosed and what does it affect?
Later in life; lung & liver
What is α1-antitrypsin and what does it do?
A protease inhibitor of the serine protease elastase, which is released by activated neutrophils at the airway, destroying elastin in the connective tissues
Where is α1-antitrypsin made and where does it go?
Made in liver and travels to lungs through the blood.
Of two mutant alleles in α1-antitrypsin, Z & S, which genotypes causes the lowest amount of normal SERPINA1 levels?
Z/Z genotype has ~15% normal SERPINA1 level
S/S genotype has 50-60% normal SERPINA1 level
What is the treatment for ATD?
Treatment for lung disease (COPD): inhaled bronchodilators and inhaled steroids, vaccinations against flu/pneumonia, pulmonary rehab oxygen, lung transplant
Treatments in development: ERT, gene therapy, release of misfolded AAT protein from liver to blood
What is the disease classification of α1-antitrypsin deficiency?
Autosomal Recessive
What is the disease classification of Tay-Sachs Disease?
Autosomal Recessive
Tay-Sachs Disease (Gm2 gangliosidosis type I) causes the progressive destruction of what?
The central nervous system
What is the lifespan of a patient with Tay-Sachs?
~2-4 years of age
What is the biochemical defect of Tay-Sachs Disease?
A lysosomal storage disorder with >300xs accumulation of Gm2 ganglioside in the lysosome.
Tay-Sachs Disease is usually caused by a mutation in what gene? What is this gene responsible for?
Mutation in HEXA gene which makes the alpha subunit of teh enzyme hexosaminidase A which degrades Gm2 ganglioside.
Mutation in the HEXB gene causes which disease?
Sandhoff disease
What enzyme is defected in Tay-Sachs?
Hexosaminidase A
What is the disease classification of Achondroplasia?
Autosomal dominant
What is the disease classification of Huntington’s Disease?
Autosomal dominant
What is the disease classification of Tuberous Sclerosis?
Autosomal dominant