Multifactorial disorders Flashcards
What are the ways in which you can determine if a multifactorial disease has a genetic component?
Familial clustering (relative risk to second sibling)
Twin studies
What is ascertainment bias?
Where you deliberately collect data that tends to prove your hypothesis.
How do you account for ascertainment bias?
Determine the relative risk to the second sibling of every proband.
How do you calculate the lambda s (relative risk to second sibling)?
Risk to sibling over risk to general population. E.g. if risk to gen. pop. is 1% and risk to sibling is 9% lambda s = 9/1 = 9.
How might twin studies be used to show a genetic component?
Genetic characters should have a higher concordance in monozygotic twins compared to dizygotic twins.
Why would you use an association study?
To determine which alleles contribute to multifactorial disorders.
What is the purpose of a genetic association study?
To relate variation in human DNA sequence with a disease or trait. Estimates population-attributable risk.
What is linkage disequlibrium?
Most disease-bearing chromosomes in population are descended from one or few ancestral chromosomes.
What is the thrifty phenotype hypothesis?
If maternal malnutrition occurs the baby will have an increased risk of developing type 2 diabetes.
What is the lambda s for Alzheimer’s disease?
Between 3 and 10.
Which form of Alzheimer’s is known to be genetically heterogenous?
Early-onset (pre-40).
Which allele is most associated with risk of developing AD?
APO-E
Which APO-E haplotype confers the most risk for AD?
E4.
Which APO-E haplotype confers a protective effect for AD?
E2.
What kind of study solved AMD?
Gene association study.
