Genetics 101

Question 1

autosomal dominant

Answer 1

Rare in veterinary medicine
- both males and females are equally affected as the gene is located on a non-sex linked chromosome
- requires 1 copy of the affected gene to cause disease

ex. polycystic kidney dz in persian cats and progressive rod/cone degeneration/atrophy in english mastiffs and bullmastiffs

Question 2

Autosomal Recessive

Answer 2

MOST COMMON
- requires 2 copies of the affected genes to express disease while 1 copy will be carriers

ex. congenital myathenia gravis or smooth fox terriers or other breeds with PRCD

Question 3

penetrance (only autosomal recessive)

Answer 3

number of individuals with the affected genotypes that express the phenotype

complete: 100% will have disease
incomplete: only some will express disease

Question 4

At Risk

Answer 4

realistic calculation based on penetrance and whats happening in the population - how severely is an animal with the genotype for a disease going to be affected by it

ex. von willibrands in dobermans - high rate of mutation but low rate of pure disease (70%) are carriers of the double mutation

Question 5

polygenic traits

Answer 5

trait/disease controlled by two or more genes

Question 6

why do polygenetic traits complicate breeding?

Answer 6

conditions that are polygenetic usually range in how they affect an individual – some animals are severely affected while others are clinically normal with others somewhere inbetween

Question 7

polygenetic traits may also be influenced by __

Answer 7

outside factors

ex. hip dysplasia

animals may be genetically predisposed to hip laxity but laxity but laxity is also influenced by diet/exercise (overfeeding puppies makes it worse) and the environment

Question 8

what portion of an animals temperament is related to genetics?

Answer 8

80%

Question 9

how should genetic disease be managed through breeding?

Answer 9

• breeding the weak to the strong-> breed genetically sound animals free of disease to those who may carry or have it -> sounds counterintuitive but increases genetic variability of the breed in the long run
• screen for the diseases we can
• minimize poor environemental influence
• keep up to date on research related to the condition of concern