Autosomal inheritance Flashcards
Define phenotype
observed properties (different levels such as physical or cellular phenotype) of an individual as determined by genotype and environment.
properties can be based on the genotype as well as the environment
Define autosomal dominant (AD), autosomal recessive(AR), and codominant phenotypes
AD=> phenotype present in the heterozygote
AR=>phenotype not apparent in the heterozygote
Codominant=>both alleles expressed in the heterozygote
Track segregation of alleles through a pedigree and be able to relate genotypes to phenotypes
AD=> -often seen in multiple generations of a family and affects both sexes and transmitted by either sex
-each offspring of an individual has a 50% chance to be affected
AR=>on avg, 2 carrier parents: 25% affected offspring, 25% homozygous normal offspring, 50% heterozygous carrier offspring
- parents of an affected individual are obligate carriers and often normal
- mutations are transmitted through many generations of heterozygous carriers and may be present in only one sibship
If a person has the genotype for sickle cell disease, but does not show the phenotype outwardly, how else will the phenotype be present?
-cellular level
When looking at the heterozygote (Aa), and there is no phenotype presence of the A then what type of trait is it?
-AR
If a patient has a genotype of aa but is normal phenotypically, what type of trait is it?
-AD
If a patient has an autosomal dominant genotype, how many dominant alleles must be present for the patient to have the disease?
-1 allele
Why do most autosomal dominant diseases rarely have 2 dominant alleles so you should assume the person is heterozygous for the condition (Aa)?
-most conditions the homozygous mutant is lethal
Which trait, AD or AR, has the most number of heterozygous non-affected carriers?
-AR
What could a loss of function mutation cause?
(Three things)
Loss of function mutations are common
- terminates the protein (nonsense)
- interfere with folding, unstable, degraded
- protein produced but active site or confirmational change occurs then it is a loss of function
What is a gain of function mutation?
mutation causes protein to be expressed to lose control to cause over expression or expressed in the wrong tissues
What is a dominant negative mutation in collagen cause?
osteogenesis imperfecta due to collagen disruption
What is haploinsuffiency?
-half is not enough so if there is an autosomal dominant gene present then it will still cause the disease
Which trait, AD or AR, is characteristic of male-male transmission which helps distinguish the disorder from X-linked disorders?
AD
T/F Reduced penetrance and variable expressivity occur frequently in AD disorders
True