Genetic disease Flashcards
what is a genotype?
-the genetic constitution of an individual
what is a phenotype?
- the physical properties an individual shows
- has both genetic and environmental factors
what is an allele?
one of several forms of a gene at a specific locus
what is penetrance?
amount of people with a gene/genotype that display the expected phenotype
what is complete penetrance?
gene/genes for a trait are expressed in a whole population.
what is incomplete penetrance?
gene/genes for a trait are only expressed in part of the population.
what is variable expression?
variation in clinical features of a genetic disease in individuals with the same genetic variation
what is sex limitation?
expression of a particular characteristic limited to one sex
what is multifactorial conditions? (in terms of genetic disease)
disease due to a combination of environmental and genetic factors
describe an autosomal dominant disease.
- a disease that only manifests in a heterozygous state
- 50% chance of offspring being affected
describe an autosomal recessive disease.
- a disease that manifests only in a homozygous state
- 25% of offspring being affected
- 50% chance of offspring being a carrier
describe an X linked genetic disease?
- caused by mutation on the X chromosome
- no father to son transmission
- all daughters from an affect father are affected
- males can never be carriers
- usually only males affected
what is lyonisation?
- the process of X chromosome inactivation
- one of 2 X chromosomes in every cell is randomly turned off in early embryonic life
- can only affect females
- in males it’s non-viable with life
what is knudson’s 2 hit hypothesis?
- gene mutations may be inherited or accquired
- sporadic cancer = 2 acquired mutations
- hereditary cancer = 1 inherited + 1 acquired
