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STEP1 > Random Genetic Diseases > Flashcards

Random Genetic Diseases Flashcards

1
Q

Kartagener Syndrome (what is it?, what does it cause? how is it inherited?)

A

Dynein arm defect -> immotile cilia

Causes: dec. fertility (sperm/fallopian tube dysfunction), inc. risk ectopic pregnancy, bronchiectasis, recurrent sinusitis, chronic ear infections, hearing loss, situs inversus

Autosomal recessive

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2
Q

Primary ciliary dyskinesia (what is it?)

A

Group of disorders similar to Kartagener WITHOUT situs inversus

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3
Q

Osteogenesis Imperfecta: what is it? what causes it?

A

Brittle bone disorder

Genetic bone disorder due to variety of gene defects: most commonly COL1A1 and COL1A2

Common type is AD: decreased production of Type I collagen (collagen is normal)

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4
Q

Osteogenesis Imperfecta: How does it present?

A
  1. Multiple fractures with minimal trauma (could happen during birth)
  2. BLUE sclerae (translucent CT over choroidal veins)
  3. Tooth abnormalities: opalescent teeth that wear easily bc they lack dentin (supports enamel)
  4. Progressive Hearing loss

“Patients can’t BITE”: Bones I(eye) Teeth Ear

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5
Q

Ehlers-Danlos Syndrome: what is it? How is it inherited? How does it present?

A

Faulty collagen synthesis -> hyperextensible skin, easy bleeding/bruising, hypermobile joints

Different types, different inheritance patterns

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6
Q

Ehlers-Danlos possible complications

A

Joint dislocation, berry/aortic aneurysms, organ rupture

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7
Q

Types of Ehlers-Danlos

A
  1. Hypermobility type: most common, joint instability
  2. Classical type: type V collagen mutation COL5A1/COL5A2, joint and skin Sx
  3. Vascular type: deficient type III collagen, vascular/organ rupture
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8
Q

Collagen Type I

A

most common: bone, skin, tendon, dentin, fascia, cornear, late wound repair

osteogenesis imperfecta

“bONE”

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9
Q

Collagen Type II

A

Cartilage, vitreous body, nucleus pulposis

“carTWOlage”

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10
Q

Collagen Type III

A

Reticuluin - skin, blood vessels, uterus, fetal tissue, granulation tissue

Ehlers-Danlos vascular type

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11
Q

Collagen Type IV

A

Basement membrane, basal lamina, lens

Alport Syndrome, Goodpasture syndrome

“type 4 under the floor (basement)”

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12
Q

Menke’s Syndrome (what is it?, how it is inherited?, how does it present?)

A

X-linked recessive

CT disease due to impaired Cu absorption/transport due to defective Menkes protein: leads to decreased lysyl oxidase activity (needs Cu as a cofactor, responsible for cross-linking collagen/elastin)

Presentation: brittle kinky hair, hypotonia, growth retardation

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13
Q

Marfan Syndrome: what causes it/how is it inherited?

A

Autosomal Dominant

CT disorder due to mutation of chromosome 15 which results in a defective fibrillin protein

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14
Q

Marfan Syndrome: Presentation

A
  1. tall w long extremities
  2. pectus carinatum (pigeon chest)/excavatum (chest sinks in)
  3. hypermobile joints
  4. arachnodactyly: long tapering fingers/toes (spider fingers)
  5. Heart problems: cystic medial necrosis of aorta, aortic incompetence, aortic dissection, floppy mitral valve
  6. Subluxation of lens: upward/temporally
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15
Q

Fibrillin

A

Forms a sheath around elastin

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16
Q

alpha1-antitrypsin deficiency

A

a1-at normally inhibits elastase: deficiency leads to inc breakdown of elastin

LINKED WITH EMPHYSEMA

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17
Q

McCune-Albright Syndrome: what is it? how is it inherited?

A

Mutation with G protein signaling

Mosaicism! otherwise it would be lethal

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18
Q

McCune-Albright Syndrome: presentation

A

Unilateral cafe-au-lait spots with ragged edges, at least 1 endocrinopathy (ex. precocious puberty), polyostotic fibrous dysplasia (when normal bone marrow is replaced with fibrous tissue making it weak/prone to expansion, can lead to fx/deformity/pain)

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19
Q

Prader-Willi syndrome: how is it inherited?

A

Maternal imprinting on chromosome 15

aka mom’s gene is silent, and Paternal gene is mutated/deleted

25% of cases due to maternal uniparental disomy: aka you get 2 silent mom copies, no paternal copies of gene

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20
Q

Prader-Willi syndrome: presentation

A

Hyperphagia (polyphagia), obesity, intellectual disability, hypogonadism, hypotonia

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21
Q

Angelman syndrome: how is it inherited?

A

Paternal imprinting on chromosome 15

aka dad’s gene is silent and Maternal gene is mutated/deleted

5% cases due to paternal uniparental disomy: aka you get 2 silent dad copies, no maternal copies of gene

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22
Q

Angelman syndrome: presentation

A

Inappropriate laughter, seizures, ataxia, severe intellectual disabilities

“happy puppet”

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23
Q

Hypophosphatemic rickets

A

Vitamin-D resistant rickets is other name.

X-linked dominant disorder causing increased phosphate wasting at proximal tubule: FGF-23 expression is increased and this promotes phosphaturia

Results in rickets-like presentation

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24
Q

Cystic fibrosis: mutation/inheritance

A

Autosomal recessive, defect in CFTR gene on chromosome 7

commonly a deletion of Phe508

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25
Q

Cystic fibrosis: pathophysiology

A

CFTR codes for ATP-gated Cl channel that secretes Cl in lungs/gut and reabsorbs Cl from sweat gland

Common mutation results in CFTR protein misfolding so you lose that channel: you can’t secrete Cl so it remains in the cells -> increased Na reabsorption into cells to balance charge -> increased H2O reabsorption -> abnormally thick mucus secreted in lungs and GI tract that is hard to clear

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26
Q

Cystic fibrosis: diagnosis

A

Cl concentration greater than 60 in the sweat is diagnostic

Can present like contraction alkalosis and hypokalemia bc of the ECF H2O and Na loss

In newborn screenings: can look at increased immunoreactive trypsinogen

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27
Q

Cystic fibrosis: complications

A

Recurrent pulmonary infections (Staph auerus in early infancy, pseduomonas in adolescence), chronic broncitis, bronchiectasis

Pancreatic insufficiency, malabsorption with steatorrhea, fat-soluble vitamin deficiencies, biliary cirrhosis, liver disease

Meconium ileus in children

Infertility in men, subfertility in women (amenorrhea due to super thick cervical mucus)

Nasal polyps

Clubbing of nails

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28
Q

Cystic fibrosis: treatment

A

for mucus clearance: chest physiotherapy, albuterol, aerosolized dornase alfa DNAse, hypertonic saline

Anti-inflammatory: Azithromycin

Pancreatic enzymes

Ibuprofen slows disease progression

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29
Q

Duchenne Muscular Dystrophy: how is it inherited?

A

X linked disorder due to FRAMESHIFT/nonsense mutations that lead to truncated/absent dystrophin protein

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30
Q

Becker Muscular Dystrophy: how is it inherited?

A

X linked disorder due to NON-FRAMESHIFT deletions in the dystrophin gene

31
Q

Dystrophin

A

Gene is largest protein-coding human gene so increased risk for mutations.

Helps to anchor muscle fibers (actin in the cytoskeleton) to the ECM

Loss = myonecrosis

32
Q

Duchenne Muscular Dystrophy: presentation, onset, how is it diagnosed?

A

Myofiber damage. Weakness starts in pelvic girdle muscles and progresses superiorly

Pseudohypertrophy of calf muscles due to fibrofatty replacement of the muscle

Waddling gait

Dilated cardiomyopathy

Onset before age 5, diagnosed via genetic testing, will also have elevated CK and aldolase

33
Q

Becker Muscular Dystrophy: presentation, onset

A

Less severe than DMD, onset adolescence

34
Q

Myotonic Type 1 Muscular Dystrophy: inheritance

A

Autosomal dominant, CTG trinucleotide expansion repeat in DMPK gene leading to abnormal expression of myotonin protein kinase

35
Q

Myotonic Type 1 Muscular Dystrophy: presentation

A

Myotonic, muscle wasting, cataracts, testicular atrophy, frontal balding, arrhythmia

Cataracts Toupee Gonadal atrophy (CTG repeats)

36
Q

Gower sign

A

When pt uses upper extremities to help stand up, seen in DMD and other muscular dystrophies and inflammatory myopathies

37
Q

Fragile X syndrome: inheritance

A

X-linked dominant, trinucleotide repeat in FMR1 gene leads to hypermethylation and decreased expression

CGG repeat

38
Q

Fragile X Syndrome: presentation

A

Most common cause inherited intellectual disability/autism

Post-pubertal macroorchidism (enlarged testes), long face, large jaw, everted ears, mitral valve prolapse

Chin, Giant Gonads (CGG repeat)

39
Q

22q11 deletion syndromes: what are they, how do they typically present?

A

Microdeletions at chr 22q11, have variable presentations

CATCH 22:
Cleft palate
Abnormal facies
Thymic aplasia
Cardiac defects
Hypocalcemia due to parathyroid aplasia
40
Q

DiGeorge Syndrome: what is it? how does it present?

A

22q11 deletion syndrome

Thymic, parathyroid, cardiac defects

41
Q

Velocardiofacial syndrome: what is it? how does it present?

A

22q11 deletion syndrome

Palate, facial, cardiac defects

42
Q

Williams Syndrome: what is it? how does it present?

A

Deletion of long arm of chr 7 that includes the elastin gene

Presentation: elfin face, intellectual disability, extreme friendliness with strangers, CV problems, hypercalcemia due to increased Vitamin D sensitivity, well developed verbal skills

43
Q

Cri-du-chat syndrome: what is it? how does it present?

A

Deletion of sort arm of chr 5

Presentation: microcephaly, intellectual disability, high-pitched crying/meowing, epicanthal folds, VSD cardiac problem

44
Q

Patau syndrome: what is it?

A

Trisomy 13

45
Q

Patau syndrome: pregnancy screen

A

First trimester screen shows decreased free BHCG, decreased PAPP-A

46
Q

PAPP-A

A

Pregnancy-associated plasma protein A

Protease, main substrates are insulin-like growth factor binding proteins

47
Q

Patau syndrome: presentation

A
  1. Intellectual disability
  2. Rocker bottom feet
  3. Microphtlamia
  4. Microcephaly
  5. Cleft lip/palate
  6. Polydactyly
  7. Cutis aplasia (hole on top of head thing)
  8. Congenital heart defects
  9. Holoprosencephaly: embryo fails to develop 2 hemispheres
48
Q

Patau syndrome: prognosis

A

Death by age 1

49
Q

Edwards syndrome: what is it?

A

Trisomy 18

50
Q

Edwards syndrome: presentation

A
  1. Prominent occiput
  2. Rocker bottom feet
  3. Intellectual disability
  4. Nondisjunction
  5. Clenched fists with overlapping fingers
  6. Low-set ears
  7. Micrognathia, Small jaw
  8. congenital heart disease
51
Q

Edwards syndrome: prognosis

A

Death by age 1

52
Q

Edwards syndrome: screening

A

First trimester: PAPP-A and BHCG are decreased

Quad screen: decreased BHCG, estriol, alpha-fetoprotein, inhibin A (could be normal)

53
Q

Type of collagen in scars, define keloid and hypertrophic scar

A

Initially Type III and then gets replaced by type I

Keloid: disorganized Type I and III
Hypertrophic scar: Type III in parallel

54
Q

Lesch-Nyhan Syndrome: how is it inherited?

A

X-linked recessive

55
Q

Lesch-Nyhan Syndrome: what is the pathophys?

A

Lack of HGPRT enzyme which is used in the purine salvage pathway (recycles guanine to GMP and hypoxanthine to IMP)

You end up with excess uric acid production

56
Q

Lesch-Nyhan syndrome: how does it present?

A

Hyperuricemia
Gout
Pissed off: aggressive behavior, lip biting, self mutilation
Retardation: intellectual disability
T: dysTonia, choreoathetosis (writing movement)

57
Q

Lesch-Nyhan syndrome: how do you treat it?

A

Allopurinol, Febuxostat: you want to decrease amt of uric acid

Doesn’t treat the neuro sx though

58
Q

Adenosine deaminase deficiency: what is it?

A

you lack ADA enzyme which is needed for degradation of adenosine

59
Q

Adenosine deaminase deficiency: what is it a cause of?

A

Autosomal recessive SCID!

60
Q

Xeroderma pigmentosum: what is it?

A

defect in nucleotide excision repair so you can’t remove pyrimidine dimers that are formed due to UV light exposure

61
Q

Xeroderma pigmentosum: how does it present?

A

Increased risk for skin cancer: melanoma, basal cell skin CA, squamous cell skin CA

62
Q

Lynch syndrome: what is the defect in?

A

Nucleotide mismatch repair

63
Q

Lynch syndrome: what is another name for it?

A

Hereditary nonpolyposis colorectal cancer

64
Q

Lynch syndrome: sequelae

A

Colon CA, endometrial CA

65
Q

Ataxia telangiectasia: what is it?

A

Defect in non-homologous end joining in DNA repair

66
Q

Ataxia telangiectasia: how does it present?

A

IgA deficiency, cerebellar ataxia, poor smooth pursuit with eyes, elevated AFP at 8 months, sensitivity to XR radiation

67
Q

I-cell disease: what is it

A

Inherited lysosomal storage disease where the Golgi is unable to phosphorylate mannose residues on glycoproteins

This means that these proteins are NOT targeted for the lysosome but are instead secreted extracellularly

68
Q

I-cell disease: how does it present?

A

Coarse facial features, cloudy corneas, restricted joint movement, high levels of lysosomal enzymes in plasma

Often fatal

69
Q

Down’s Syndrome: what is it

A

Trisomy 21

Most common viable chromosomal disorder, most common cause of intellectual disability

70
Q

Down’s Syndrome: how does it present?

A
  1. Intellectual disability
  2. Flat facies
  3. Prominent epicanthal folds
  4. Single palmar crease
  5. Gap btw 1st and 2nd toe
  6. Duodenal atresia
  7. Hirschsprung disease
  8. ASD/other congenital heart defects
  9. Brushfield spots (white spots in periphery of iris)

Early onset Alzheimers, Increased risk ALL/AML

71
Q

Down’s Syndrome: what causes it

A

95% of cases due to meiotic nondisjunction which increases with maternal age

4% of cases due to unbalanced Robertsonian translocation btw chr 14 and 21

1% of cases due to mosaicism

72
Q

Down’s Syndrome: what will the first trimester US show?

A

Increased nuchal translucency, hypoplastic nasal bone

Decreased serum PAPP-A, increased free BHCG

73
Q

Down’s Syndrome: what will the second trimester quad screen show?

A

dec AFP, inc BHCG, dec estriol, inc inhibin A

STEP1 (11 decks)

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