Genetics

Question 1

Which autosomal dominant disease is a/w floppy mitral valve, dissecting aortic aneurysm, berry aneurysm?

Answer 1

Marfan’s syndrome (fibrillin 1 defect)

Question 2

Which autosomal dominant disease is a/w mitral valve prolapse, liver disease, berry aneurysms?

Answer 2

Autosomal dominant polycystic kidney disease (ADPKD)

Question 3

Which autosomal dominant disease has neural tumors and pigmented iris hamartomas?

Answer 3

neurofibromatosis type 1

Question 4

Which autosomal dominant disease has a very strong association with colon cancer

Answer 4

FAP (APC gene)

Question 5

Which autosomal dominant disease can cause MI before age 20?

Answer 5

Familial hypercholesterolemia (hyperlipidemia type IIa)

Question 6

Which autosomal dominant disease has hemangioblastomas of the retina/ cerebellum/ medulla?

Answer 6

von-hippel lindau

Question 7

Which autosomal dominant disease has increased MCHC and hemolytic anemia?

Answer 7

Hereditary spherocytosis

Question 8

Which autosomal dominant disease has bilateral acoustic schwannomas?

Answer 8

Neurofibromatosis type 2

Question 9

Which autosomal dominant disease has facial lesions, seizure disorder, cancer risk

Answer 9

Tuberous sclerosis

Question 10

Which autosomal dominant disease has caudate atrophy and dimentia?

Answer 10

Huntingtons

Question 11

Which autosomal dominant disease has cystic medial necrosis of the aorta?

Answer 11

Marfans

Question 12

Which autosomal dominant disease has a defect of the fibroblast growth factor (FGF) receptor 3

Answer 12

Achrondroplasia (a/w advance paternal age)

Question 13

Which renal lysosomal storage disease is associated with renal failure

Answer 13

Fabry’s disease (dialysis treats renal disease)

Question 14

What are the only two X linked recessive lysosomal storage disease? What is the mode of inheritance of the others?

Answer 14

Fabry’s and Hunters. Autosomal recessive

Question 15

What is the most common lysosomal storage disorder

Answer 15

Gaucher’s disease

Question 16

Which lysosomal storage diseases are associated with an early death (usually by age 3)

Answer 16

Tay-sachs, Niemann-Pick, Krabbe’s disease

Question 17

Which lysosomal storage disease is a demyelinating disease?

Answer 17

Metachromatic leukodystrophy

Question 18

How might corneal clouding and mental retardation help distinguish between the mucopolysaccharidoses?

Answer 18

Hurler’s- corneal clouding (+) Mental retardation (+)
Hunter’s- corneal clouding (-) Mental retardation (+)
Scheie’s- corneal clouding (+) Mental retardation (-)
I-cell- corneal clouding (+) Mental retardation (+/-)

Question 19

Which lysosomal storage disorder is deficient in alpha-L-iduronidase

Answer 19

Hurler’s and Scheie’s (Scheie’s is pretty much just a more mild form of Hurler’s and doesnt have the mental retardation)

Question 20

Which lysosomal storage disorder is deficient iduronate suflatase

Answer 20

Hunter’s syndrome

Question 21

Which lysosomal storage disorder is deficient in arylsulfatase A

Answer 21

metachromatic leukodystrophy

Question 22

Which lysosomal storage disorder is deficient in alpha-galactosidase A

Answer 22

Fabrys (alpha gals Always look Fab)

Question 23

Which lysosomal storage disorder is deficient in galactocerebrosidase (galactocerebroside accumulation)

Answer 23

Krabbe’s (those who LAC gaLACtocerebrosidase get Krabbe)

Question 24

Which lysosomal storage disorder is deficient in Beta-glucocerbrosidase (glucocerebroside accumulation)

Answer 24

GaUcher’s (GlUcocerebrosidase deficiency)

Question 25

Which lysosomal storage disorder is deficient in hexosaminidase?

Answer 25

Tay sachs (tay saX -> heXosaminidase deficiency leads to GM2 ganglioside accumulation)

Question 26

Which lysosomal storage disorder is deficient in sphingomyelinase (sphingomyelin accumulation)

Answer 26

Niemann-Pick disease (Niemann-Pick(S) the liver and spleen. Hepatosplenomegally. (S) is for spingomyelinase.

Question 27

Characterized by an accumulation of GM2 ganglioside

Answer 27

Tay sachs

Question 28

Characterized by accumulation of dermatin sulfate

Answer 28

Hurler's, Hunter's and Scheie's

Question 29

Which lysosomal storage disorders are particularly common among the Ashkenazi Jews?

Answer 29

Tay-sachs, Niemann-Pick, some form of Gaucher's disease

Question 30

Which lysosomal storage disorder has "crinkled paper cytoplasm"?

Answer 30

Gaucher's disease

Question 31

What is the differential diagnosis for cherry red spot on the retina?

Answer 31

Tay-Sachs, Niemann-Pick, Central retinal artery occlusion

Question 32

What is the probability that a female heterozygous for an X-linked disease will pass it on to her son?

Answer 32

50%

Question 33

What is the probability that a female heterozygous for an X-linked disease that mates with a normal male will have a carrier daughter?

Answer 33

50%

Question 34

What is the probability that a female carrier of an X-linked disease will have a child with that disease assuming she mates with a normal male?

Answer 34

25%

Question 35

If aa symbolizes a recessive disease, what is the likelihood that parents Aa and Aa will have a phenotypically normal child?

Answer 35

75%

Question 36

Cystic fibrosis is an autosomal recessive disorder. Two parents that are heterozygous for cystic fibrosis have a normal, nonaffected child. What is the probability that the child is homozygous normal?

Answer 36

33% (we must remove the heterozygous recessive possibility because we no that this child is phenotypically normal)

Question 37

Upon examination of a pedigree, you not that both males and females are affected with a disease in every generation. Which genetic disease is this?

Answer 37

Autosomal dominant

Question 38

What is the frequency of the Aa genotype and the AA genotype if the frequency of a allele A is 0.95

Answer 38

``` AA = 0.95 x 0.95 = .9025 Aa = 0.95 x 0.05 x 2 = .095 ```

Question 39

If 49% of a particular population is homozygous for a curly hair gene that is dominant to a straight hair gene, what is the percentage of the population that has curly hair?

Answer 39

``` p^2 = .49 therefore p = 0.7 Therefore q = 0.3 2 x 0.7 x 0.3 = .42 0.49 (p^2) + 0.42 (2pq) = 0.91 91% of the population has curly hair ```

Question 40

Genetic disease that is a/w floppy mitral valve, dissecting aortic aneurysm, berry aneurysm

Answer 40

Marfans (auto dom)

Question 41

Genetic disease that a/w mitral valve prolapse, liver disease, berry aneurysms

Answer 41

ADPKD

Question 42

Genetic disease that has hemangioblastomas of the retina/ cerebellum/ medulla

Answer 42

Von Hippel Lindau (auto dom)

Question 43

Genetic disease that has increased MCHC and hemolytic anemia

Answer 43

Hereditary spherocytosis (auto dom)

Question 44

Genetic disease that has cafe-au lait spots and soft tissue growths

Answer 44

Neurofibromatosis type 1 (auto dom)

Question 45

Genetic disease that has macro-orchidism and autism

Answer 45

Fragile X (X linked recessive)

Question 46

Genetic disease in which endocardial cushion defects are common

Answer 46

Down syndrome

Question 47

Genetic disease with recurrent pulmonary infections and steatorrhea

Answer 47

Cystic fibrosis (auto recessive)

Question 48

Genetic disease w/ multiple fractures, easily confused with child abuse

Answer 48

Osteogenesis imperfecta (usually auto dom decrease in type 1 collagen)

Question 49

Genetic disease is that a/w Alzheimers after age 35

Answer 49

Down syndrome

Question 50

Genetic disease that prone to bilateral acoustic schwannomas

Answer 50

Neurofibromatosis type 2 (auto dom)

Question 51

Genetic disease with excess fibrofatty tissue deposits amongst muscle

Answer 51

Duchenne's Muscular dystrophy (X linked recessive) -> Calf pseudohypertrophy

Question 52

What is the test used to diagnose cystic fibrosis?

Answer 52

Chloride sweat test (> 60 mEq / L)

Question 53

What is the difference b/w Southern Blot, Northern Blot, and Western Blot?

Answer 53

SNoW DRoP Southern blot: DNA sample, DNA probe Northern blot: RNA sample, DNA probe Western blot: Protein sample, Antibody probe

Question 54

Accumulation of GM2 ganglioside

Answer 54

Tay-Sachs

Question 55

Lysosomal storage disease a/w renal failure

Answer 55

Fabry's (FabRy's -> R for renal)

Question 56

Accumulation of dermatin sulfate

Answer 56

Hurler's, Hunter's and Scheie's

Question 57

Deficiency of hexosaminidase

Answer 57

Tay sachs (tay saX -> heX)

Question 58

Two patient have the same mutation on chromosome 15 but have different phenotypic expressions. One patient received the mutation from the father while the other received the mutation from the mother. What is this an example of?

Answer 58

Imprinting (Prader-Willi and Angleman syndromes)

Question 59

Frequency of CFTR in mutation X in pts with cystic fibrosis is 0.1 Cystic fibrosis can be caused by either mutation X or mutation Y in the CFTR gene. What percentage of cystic fibrosis patients are homozygotes for mutation Y?

Answer 59

``` X = 0.1 Y = 0.9 -> Y^2 = 81% ```