Genetics Flashcards
Genotype
genetic makup of a individual
Heterozygous
have 2 different forms of a gene for specific trait/dz
Homozygous
have 2 identical forms of a gene for specific trait/dz
Penetrance
proportion of genetically affected individuals that express a trait + extent that trait is present
o = likelihood that a given gene will result in dz
o Incomplete suggest <100%
Phenotype
observable characteristics resulting from interaction of genetic makeup and environment
Polygenic
trait/dz caused by 2 or > genes
Autosomal recessive
- Carried on autosomal chromosome
- Both copies of mutation have to be present
Pedigree evaluation autosomal recessive
o Skips generations → parents can be asymptomatic carriers
o No sex predilection
o Mating of silent carriers (heterozygotes) parents → 25% affected phenotype, 75% not
o Mating of 2 affected parents → 100% affected offspring
Autosomal dominant
- Only 1 copy of mutation necessary for clinical phenotype
o Homozygote or heterozygote
Predigree eval Autosomal dominant
o At least 1 affected parent
Heterozygous → 50% affected offspring
Homozygous → 100% affected offspring
o No sex predilection
X-linked
- Gene carried on X chromosome
- Most commonly recessive
o Males almost always show phenotype since only 1 X
o Females can be silent carriers unless both X’s carry mutation
Pedigree eval X linked
o Affected males > females
o Affected males crossed w normal female → silent (unaffected) females
o Silent carrier females pass the trait to 50% male offspring
o Affected male crossed w silent carrier female → can result in affected female
Uncommon
Polygenic
- 2 or > genes working together to develop a specific trait
- Many inherited dz in vetmed
Incomplete penetrance
- <100% of individuals with mutation will have clinical trait/dz
- Variable expressivity of trait → severity of phenotypic expression
Which diseases are proven heritable?
Endomyocardial fibrosis
ASD
PDA
PS
SAS
TOF
TVD
VSD
