4 characteristics of complex traits?
1) aggregate in families 2) do not follow simple Mendelian inheritance 3) due to variants in multiple genes and non-genetic factors 4) no simple relationships in the population
A ____ heritability implies that differences among individuals with respect to a trait in a population can be attributed to differences in the genetic make-up.
_____ is indicated when there is an increased risk to relatives, but there is no consistent pattern of inheritance within families.
Give an example of incomplete penetrance.
Type I diabetes and MHC
When there is an increased risk to relatives, but there is no consistent pattern of inheritance within families.
Give an example of an allele-linked heterogeneity disease.
Give an example of a variation due to the presence of phenocopies.
Thalidomide-induced limb malformation vs. genetically-induced
Presence of phenocopies
Individuals who have the disease or trait for reasons that are not primarily genetic even though clinical presentation mimics the more genetic version
Who are studied to try to determine genetic vs. environmental causes of variation in traits?
twins (monozygotic vs dizygotic)
The _______ of a trait is the proportion of total variance in a trait that is due to variation in genes.
not everyone with predisposing variant develops disease
A low heritability does not imply that _____ is not important.
A high heritability does not imply that _____ are not important.
Give an example of a locus-linked heterogeneity disease.
The heritability of a trait is the proportion of total variance in a ____ that is due to variation in ____.
Give an example of variable expressivity.
Maturity Onset Diabetes in the Young (MODY)
no two individuals with the same genetic variant have exactly the same disease characteristics
Simple Mendelian diseases are generally ______ characterized by inheritance patterns.
The “same” disease can be caused by different alleles at one location or by alleles at different locations in the genome
Complex traits demonstrate one or more of the following:
1) incomplete penetrance 2) variable expressivity 3) heterogenicity 4) Presence of phenocopies