Genetic Disorders

Question 1

How do you screen prenatally Down syndrome?

Answer 1

Maternal serum levels

• Alfa-fetoprotein
• chorionic gonadotropin
• unconjungated estriol

Question 2

Causes of female pseudohermaphroditism

Answer 2

• congenital adrenal hyperplasia
• androgen-producing tumors
• exogenous androgens

Question 3

Cause of male pseudohermaphroditism

Answer 3

Testicular feminization

Question 4

How can you make diagnosis of cystic fibrosis?

Answer 4

• sweat test (⬆️ NaCl)

- DNA probes: allele-specific oligonucleotide (ASO) probes

Question 5

Treatment of PKU

Answer 5

Restriction of phenylalanine and aspartame

Question 6

Disease common is Ashkenazi Jews (1 in 30 carrier rate), accumulation of GM2 ganglioside in CNS and retina, mutation of HEXA gene on chromosome 15. Disease and enzyme altered, pattern of inheritance.

Answer 6

• Tay-Sachs
• hexosaminidase A
• autonomic recessive

Question 7

Difference between Tay-Sachs and Niemann-pick clinical presentation

Answer 7

Niemann-pick: reticuloendothelial system involvement ▶️ hepatosplenomegaly, lymphadenopathy, bone marrow involvement

Question 8

Most common genetic causes of mental retardation

Answer 8

• Down syndrome

- Fragile X syndrome

Question 9

Only glycogen storage disease that is also a lysosomal storage disease, and what is the deficiency enzyme?

Answer 9

• Pompe disease

- acid maltase (Alfa-1,4 glucosidase)

Question 10

Parents reporting black color diapers of his/her child, after the diapers stay for a while, what disease suggest? And why?

Answer 10

• alkaptonuria
• oxidation of homogentisic acid

*homogentisic acid (made from degradation of tyrosine and phenylalanine) is excreted into urine in patients who have a deficiency of the liver enzyme homogentisic acid oxidase. If the urine is allowed to stand, the homogentisic acid becomes oxidized, producing a black compound.

Question 11

Three autosomal recessive diseases that usually lead to death by 2 or 3 years of age

Answer 11

• Pompe disease (deficiency of lysosomal -1,4-glucosidase, or acid maltase)
• Tay-Sachs disease (deficiency of hexosaminidase A)
• Niemann-Pick disease (deficiency of sphingomyelinase)

Question 12

Endocrine neoplasm associated with neurofibrimatosis type I?

Answer 12

Phechromocytoma

Question 13

In ehler-danlos type 9 disease why is there a low ceruloplasmin and serum copper concentration and which is the consequence?

Answer 13

• mutation on copper-binding protein on chromosome X

- ⬇️ activity of lysyl oxidase (copper dependent) ▶️ inhibits cross-linking of collagen fibers