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Flashcards in biochem: genetics Deck (45):
1

hypophosphatemic rickets

vit-D resistant. X-linked dominant. incr. phosphate wasting at proximal tubule

2

mitochondrial myopathies

rare, present w/myopathy, lactic acidosis, and CNS dz. caused by failure of oxidative phosphorylation. muscle Bx shows "ragged red fibers"

3

polycystic kidney dz

autosomal dominant. b/l massive enlargement of kidneys due to multiple large cysts. 85% due to PKD1 mutation on chromosome 16

4

familial adenomatous polyposis

autosomal dominant. colon becomes covered w/adenomatous polyps after puberty. progresses to CA unless colon is resected. mutations on chromosome 5q

5

familial hypercholesterolemia

autosomal dominant. defective/absent LDL receptor -> elevated LDL -> severe atherosclerosis, corneal arcus, tendon xanthomas

6

hereditary hemorrhagic telangiectasia

autosomal dominant. inherited disorder of blood vessels -> branching skin lesions, recurrent epistaxis, skin discolorations, AVMs, GI bleeding, hematuria

7

hereditary spherocytosis

autosomal dominant. spheroid erythrocytes due to spectrin or akyrin defect; hemolytic anemia; inc. MCHC, inc. RDW. Tx: splenectomy

8

HD

autosomal dominant. -> depression, progressive dementia, choreiform movements, and caudate atrophy. inc. DA, dec. GABA, dec. ACh in the brain. gene on chr. 4 - trinucleotide repeat d/o (CAG). demonstrates anticipation: more repeats -> younger age of onset

9

li-fraumeni syndrome

autosomal dominant. abnormalities in TP53 -> multiple malignancies at young age. sarcoma, breast, leukemia, adrenal gland.

10

marfan syndrome

autosomal dominant. FBN1 gene mutation on chromosome 15 -> defective fibrin (scaffold for elastin) -> connective tissue d/o. lens subluxation is typically upward

11

MEN

autosomal dominant. familial tumors of endocrine glands (pancreas, parathyroid, pituitary, thyroid, and adrenal medulla). MEN 1 - MEN1 gene. MEN 2 - RET gene

12

NF1

autosomal dominant. neurocutaneous d/o - cafe au lait spots, cutaneous neurofibromas, optic gliomas, pheochromocytomas, lisch nodules (pigmented iris hamartomas). 100% penetrance, variable expression. caused by NF1 mutation on chr. 17

13

NF2

autosomal dominant. b/l acoustic schwannomas, juvenile cataracts, meningiomas, and ependymomas. NF2 mutation on chr. 22 (NF2=chr22)

14

tuberous sclerosis

autosomal dominant. neurocutaneous d/o w/multi-organ involvement. numerous benign hamartomas. incomplete penetrance, variable expression

15

von hippel-lindau dz

autosomal dominant. development of many benign and malignant tumors. deletion of VHL tumor suppressor gene on chromosome 3p (3 word name)

16

autosomal recessive dzs

albinism, PKD, CF, glycogen storage dzs, hemochromatosis, kartageners, mucopolysaccharidoses (except hunter), phenylketonuria, SS anemia, sphingolipidoses (except fabry), thalassemias, wilson dz

17

CF mutations

typically CFTR on chr. 7. commonly Phe508.

18

CFTR encodes

ATP-gates Cl channels, secreting Cl in lungs and GI, reabsorbing Cl in sweat glands -> abnormally thick mucus

19

CF Dx

inc. [Cl] (>60mEq/L) in sweat. Can present with contraction alkalosis and hypokalemia (like loop diuretic). inc. immunoreactive trypsinogen on newborn screen.

20

CF complications

lung infections (pseudomonas), chronic bronchitis, bronchiectasis, reticulonodular pattern on CXR, pancreatic insufficiency, malabsorption w/steatorrhea and nasal polyps. meconium ileus in newborns. infertility in males. fat-soluble vit deficiencies (ADEK)

21

CF Tx

N-acetylcysteine to loosen mucus plugs (cleaves disulfide bonds w/in mucus glycoproteins), dornase alfa (DNAse) to clear leukocytic debris

22

X-linked recessive d/os mnemonic

Be Wise, Fool's GOLD Heeds Silly HOpe: Bruton agammaglobulinemia, Wiskott-aldrich syndrome, Fabry dz, G6PD, Ocular albinism, Lesch-nyhan syndrome, Duchenne (and becker) muscular dystrophy, Hunter Syndrome, Hemophilia A and B, Ornithine transcarbamylase deficiency

23

Duchenne muscular dystrophy

Duchenne = deleted dystrophin. x-linked frameshift mutation -> truncated dystrophin -> inhibited muscle regeneration. Begins in pelvic girdle, progresses superiorly. Pseudohypertrophy of calf muscles due to fibrofatty replacement. Gower maneuver, waddling gait. Onset before 5. Die of dilated cardiomyopathy

24

Becker muscular dystrophy

x-linked non-frameshift insertions in dystrophin gene -> partially fxnal protein -> less severe, later onset.

25

myotonic type 1 muscular dystrophy

autosomal dominant. CTG trinucleotide repeat expansion in DMPK gene -> abnormal expression of myotonin protein kinase -> myotonia, muscle wasting, cataracts, testicular atrophy, frontal balding, arrhythmia. My Tonia, My Testicles, My Toupee, My Ticker

26

Fragile X syndrome

x-linked defect affecting methylation and expression of FMR1 gene = 2nd most common cause of genetic intellectual disability. Post-pubertal macroorchidism, long face w/large jaw, large everted ears, autism, miral valve prolapse

27

trinucleotide repeat expansion dzs mnemonic

Try hunting for my fried eggs: Huntington's, myotonic dystrophy, friedreich ataxia, fragile X. or X-Girlfriend's First Aid Helped Ace My Test.

28

chr. 3 d/o

von hippel-lindau, renal cell carcinoma

29

chr. 4 d/o

ADPKD w/PKD2 defect, HD

30

chr. 5 d/o

cri-du-chat syndrome, familial adenomatous polyposis

31

chr. 7 d/o

williams syndrome, CF

32

chr. 9 d/o

friedreich ataxia

33

chr. 11 d/o

wilms tumor

34

chr. 13 d/o

patau syndrome, wilson dz

35

chr. 15 d/o

parader-willi, angelman syndrome

36

chr. 16 d/o

ADPKD w/PKD1 defect

37

chr. 17 d/o

NF1

38

chr. 18 d/o

edwards syndrome

39

chr. 21 d/o

down syndrome

40

chr. 22

NS2, digeorge syndrome (22q11)

41

chr. X d/o

fragile X, X-linked agammaglobinemia, klinefelter

42

robertsonian translocation

long arms of 2 acrocentric chromosomes fuse at the centromere and 2 short arms are lost. balanced translocations -> normal phenotype. unbalanced translocations -> miscarriage, stillbirth, chromosomal imbalance

43

cri-du-chat syndrome

congenital microdeletion of 5p -> microcephaly, intellectual disability, high-pitched crying, epicanthal folds, VSD

44

williams syndrome

congenital microdeletion of 7q (including elastin). -> elfin facies, intellectual disability, hypercalcemia (inc. vit. D sensitivity), good verbal skills, extreme friendliness, CV problems

45

CATCH-22 syndrome

microdeletion of 22q11 -> variable: cleft palate, abnormal facies, thymic aplasia (-> T cell deficiency), hypocalcemia (2/2 parathyroid aplasia). digeorge: thymic, parathyroid, and cardiac. velocardiofacial: palate, facial, and cardiac