Extensions of Mendelian Analysis - Find People
Transcript of Extensions of Mendelian Analysis - Find People
Extensions of Mendelian Analysis
• Modifications of Mendelian Ratios• Single Gene modifications• Two gene pair modifications: modified
9:3:3:1 ratios• Modification of Expression• Quantitative Genetics
Single Gene modifications
• Incomplete dominance (partial dominance) • Multiple alleles • Lethal alleles
Incomplete dominance (partial dominance)
• Expression of a heterozygous phenotype that is distinct from and usually intermediate to either homozygous phenotype
Incomplete dominance
• Tay Sachs and Sickle Cell Anemia
• Heterozygous are intermediate at
• the biochemical level.
Multiple Alleles &Co-Dominance
Two gene pair modifications: modified 9:3:3:1 ratios
Recessive Epistasis
• H allele affected
• Recessive epistasis
• Show O phenotype
• Genotype variable
Modification of Expression• Temperature effects• Pleiotropic effects • Penetrance and
Expressivity
Pleiotropic effects
Penetrance & Expressivity
No expression
Polygenic inheritance
• 2 or more genes• Show continuous
variation vsdiscontinuous
• Additive component• Distinct phenotypic
classes• Quantitative traits:
size, weight, height,IQ
Quantitative Genetics