EHJ352H1 Lecture Notes - Balancing Selection, Hypotension, Missense Mutation
26 Jan 2013
School
Department
Course
Professor
Document Summary
The genetic basis of phenotypic variation: the scale of the problem: Any 2 individuals are on average 99. 9% identical (3. 2 million differences) The differences account for heritable phenotypic variation including disease susceptibility variation. Estimated 11 million common (>1%) snps plus many many rare variants. Variation of phenotype = variation (genetic factors) + variation (environmental factors) If variation in the phenotype is at least partly due to genetic variation, then there is heritability for that trait. Heritability: the genetically determined proportion of trait variation in the population, the percentage of variation in a trait that is due to genetic factors. The presence of heritability for the trait is a prerequisite for identifying genetic variants underlying trait variation. One single gene influences the phenotype very little environmental factors. Discrete phenotypes caused by alleles segregating at a single genetic locus. Highly heritable allelic variation at the single locus is sufficient to cause disease. Phenotype is an accurate predictor of genotype.
