Genetics Flashcards
What is the chance of inheriting an autosomal dominant disease from an affected parent?
1/2, 50%
What does autosomal dominant inheritance look like?
All generations affected, all affected individuals have an affected parent.
What does autosomal recessive inheritance look like?
Affected individuals are siblings, not intergenerational. 1/4 chance of future children being affected if one child is affected.
What does Sex-linked recessive inheritance look like?
Primarily affects males. No male to male transmission. Daughters of affected fathers are all carriers and have a 50% chance of passing the disease allele on to their sons.
What does mitochondrial inheritance look like?
Affected mother passes on disease to all of her children, who may express it to varying degrees. Usually neuromuscular diseases.
If the affected/not affected status of a person who is wanting to know their likelihood of being a carrier is known, who do you account for that in a punnet square/calculation?
Exclude the disease genotype from the square or calculation.
What is q^2, 2pq, and p^2 in hardy Weinberg equation?
q^2 = prevalence of disease allele in population. 2pq = prevalence of carrier status in population. p^2 = prevalence of normal allele in population.
What types of mutations are associated with dominant diseases and why?
Gain of function (introducing a new function - the normal wildtype allele is not capable of compensating for the allele creating the new function) and dominant negative (a single allele disrupts the function and a normal allele cannot make up for it.)
What types of mutations are associated with recessive diseases and why?
Loss of function - a normal allele can make up for an abnormal one, but two abnormal alleles cause protein to not function.
What is the most common cause of normal human genetic variation?
Single nucleotide polymorphisms (change in a single base), most common is the C to T SNP (C deaminates into U which changes the RNA transcript to A).
What is linkage disequillibrium?
When genes that are close together on a chromosome are inherited together because they do not undergo separate crossing over.
What is an ancestral haplotype?
Smallest genetic unit that is inherited together due to linkage disequilibrium. Common haplotypes exist throughout the population. They are tagged with SNPs.
What is HLA and what types of diseases do mutations in it cause?
HLA is involved in recognition of self versus non-self, therefore mutation contributes to many autoimmune diseases, but can also cause other non-immune diseases such as hemochromatosis. It was used for determining matches for transplants - very polymorphic gene.
What is the Dose-responsive effect?
- having both high-risk variants multiplies risk for complex disease.
Why is it that you have a higher risk of having CAD when your mother has CAD than when your father has CAD?
Men are more likely to have CAD (a complex disorder) than women, so for a woman to have CAD she has to have had more genetic variants putting her at risk for CAD, which her children may then inherit.
