Genetics

Question 1

How many chromosomes does the dog have?

Answer 1

38 autosomal pairs and 1 pair of sex chromosomes

Question 2

How many chromosomes does the cat have?

Answer 2

18 autosomal pairs and 1 pair of sex chromosomes

Question 3

For an autosomal recessive trait, what percent of offspring will be affected after mating two heterozygous parents?

Answer 3

25%

Question 4

For an autosomal recessive trait, what percent of offspring will be affected after mating two homozygous affected parents?

Answer 4

100%

Question 5

The most common mode of inheritance in dogs and cats is _____?

Answer 5

Autosomal recessive

Question 6

Autosomal recessive nephritis (Alport syndrome) occurs in what breed of dog?

Answer 6

English Cocker Spaniel

Question 7

Exercise induced collapse in Labradors is inherited by what mode?

Answer 7

Autosomal recessive

Question 8

Cystinuria is inherited in an autosomal recessive manner in what dog breed?

Answer 8

Labrador Retriever

Question 9

Cystinuria is inherited in an autosomal dominant manner in what dog breed?

Answer 9

Australian cattle dog

Question 10

For an autosomal dominant trait, each affected offspring should have one parent that is _____?

Answer 10

Also affected (can be heterozygous or homozygous)

Question 11

Polycystic kidney disease is inherited in what manner?

Answer 11

Autosomal dominant

Question 12

Dilated cardiomyopathy in Doberman Pinschers is inherited in what manner?

Answer 12

Autosomal dominant

Question 13

X lined myotubular myopathy is identified in what dog breed?

Answer 13

Rottweilers

Question 14

The study of chromosomal number and shape is called ____

Answer 14

Cytogenetics

Question 15

In genetics, what does the term expression refer to?

Answer 15

Variation in the clinical features of a genetic disorder (how severely affected the patient is)

Question 16

What is a missense mutation?

Answer 16

A change in a single nucleotide that results in formation of a different amino acid than what is typically present

Question 17

What is a nonsense mutation?

Answer 17

A change in a single nucleotide that results in formation of a premature stop codon

Question 18

In genetics, what does the term penetrance refer to?

Answer 18

The proportion of individuals with a disease gene variant that will develop the disease. Complete penetrance = 100% of individuals have the disease. Incomplete penetrance = less than 100% develop the disease, despite having the gene mutation

Question 19

In genetics, what does the term polymorphism refer to?

Answer 19

Naturally occurring single base pair variants in the DNA sequence that do not cause disease and occur in at least 5% of the population

Question 20

All dogs/cats with abnormal sexual development or infertility should have this test performed

Answer 20

Karyotype

Question 21

Maine Coon hypertrophic cardiomyopathy is caused by what mutation?

Answer 21

A31P

Question 22

Describe the penetrance and expressivity of Maine Coon hypertrophic cardiomyopathy

Answer 22

Incomplete penetrance and variable expression

Question 23

What is pharmacogenetics?

Answer 23

The study of the impact of genetic variation on drug pharmacokinetics and pharmacodynamics

Question 24

What enzyme is responsible for metabolizing drugs such as azathioprine and 6-mercaptopurine?

Answer 24

Thiopurine methyltransferase

Question 25

Proteins in the ABC superfamily are responsible for what?

Answer 25

Transporting substrates (mainly drugs) across biologic membranes using ATP

Question 26

P-glycoprotein is encoded for by what gene?

Answer 26

ABCB1 (formerly MDR1)

Question 27

What genetic mutation in 75% of Collies and 50% of Australian shepherds leads to increased drug sensitivity?

Answer 27

4 base pair deletion in ABCB1, which causes a frame shift mutation and premature stop codon - protein is truncated and non-functional

Question 28

You should test for ABCB1 mutations before treating patients with which chemotherapeutics?

Answer 28

Vincristine, vinblastine, doxorubicin

Question 29

Name 3 drugs that should never be given to dogs with ABCB1 mutations

Answer 29

Ivermectin, loperamide, moxidectin

Question 30

What drugs can inhibit P glycoprotein (causing clinical signs similar to a mutation in ABCB1)?

Answer 30

Ketoconazole, spinosad (insecticide used for flea/tick - Comfortis)

Question 31

65% of what non-herding breed is positive for ABCB1 mutations?

Answer 31

Long haired whippets

Question 32

Dogs that were homozygous for ABCB1 mutations had higher sedation scores than dogs with normal ABCB1 function after receiving what medication?

Answer 32

Acepromazine