Genetics

Question 1

What are SNPs?

Answer 1

Single nucleotide polymorphisms; common DNA variations affecting drug metabolism and disease risk.

Question 2

What is epigenetics?

Answer 2

Heritable changes in gene expression without altering DNA sequence (e.g., methylation, histone modification).

Question 3

What is the diploid and haploid number of human chromosomes?

Answer 3

Diploid = 46; Haploid = 23.

Question 4

What is aneuploidy?

Answer 4

Abnormal chromosome number not a multiple of 23 (e.g., Trisomy 21).

Question 5

What is polyploidy?

Answer 5

Multiples of haploid number, usually not viable.

Question 6

What is an allele?

Answer 6

An alternative form of a gene; homozygous = same alleles, heterozygous = different alleles.

Question 7

What is autosomal dominant inheritance?

Answer 7

One mutant allele sufficient; 50% risk per pregnancy; examples: Huntington’s, Marfan’s.

Question 8

What is autosomal recessive inheritance?

Answer 8

Two copies required; 25% affected risk; examples: CF, PKU, Tay-Sachs.

Question 9

What is X-linked dominant inheritance?

Answer 9

One mutant allele on X enough in females; affected males pass to all daughters, no sons.

Question 10

What is X-linked recessive inheritance?

Answer 10

Mostly males affected; carrier mothers → 50% of sons affected; examples: Hemophilia A, Duchenne MD.

Question 11

What is codominance?

Answer 11

Both alleles expressed distinctly; e.g., ABO blood groups, sickle cell trait.

Question 12

What is PKU?

Answer 12

Phenylalanine hydroxylase deficiency (AR).

Question 13

What is Tay-Sachs disease?

Answer 13

Hexosaminidase A deficiency (AR).

Question 14

What is osteogenesis imperfecta type II?

Answer 14

Collagen mutation (AD).

Question 15

What is familial hypercholesterolemia?

Answer 15

LDL receptor mutation (AD).

Question 16

How are mitochondrial disorders inherited?

Answer 16

Maternal inheritance only; all children of affected female inherit, none from affected male.

Question 17

What are examples of mitochondrial disorders?

Answer 17

Kearns-Sayre syndrome; Leber’s hereditary optic neuropathy.

Question 18

What is Edwards syndrome?

Answer 18

Trisomy 18; severe abnormalities, 3:1 female:male ratio.

Question 19

What is Patau syndrome?

Answer 19

Trisomy 13; multiple anomalies, poor prognosis.

Question 20

What is Cri-du-chat syndrome?

Answer 20

5p deletion; cat-like cry, severe impairment.

Question 21

What is Turner syndrome?

Answer 21

Single X; short stature, streak ovaries, infertility.

Question 22

What is Klinefelter syndrome?

Answer 22

XXY; tall, gynecomastia, infertility, learning issues.

Question 23

What is Triple X syndrome?

Answer 23

XXX; mild intellectual disability, usually fertile.

Question 24

What is Fragile X syndrome?

Answer 24

Most common inherited cause of male intellectual disability.

Question 25

What is GINA?

Answer 25

Genetic Information Nondiscrimination Act (2008); prohibits discrimination by insurers/employers.

Question 26

What does F-GENES stand for in genetic red flags?

Answer 26

Family history, Group of anomalies, Extreme presentation, Neurodevelopmental delay, Exceptional pathology, Surprising labs.