How to Determine the Genetic Components of Complex Diseases? Family, twin and adoption studies Segregation analysis Linkage analysis Association studies and linkage disequilibrium Identification of DNA sequence variants conferring susceptibility
How to Determine the Genetic Components of Complex Diseases? • Family, twin and adoption studies • Segregation analysis • Linkage analysis • Association studies and linkage disequilibrium • Identification of DNA sequence variants conferring susceptibility
Trait: Any detectable phenotypic property or character Qualitative trait: A genetic disease trait that either present or absent. The pattern of inheritance for a qualitative trait is typically monogenetic, which means that the trait is only influenced by a single gene Quantitative trait: are measurable characteristics such as height, blood pressure, serum cholesterol, and body mass index. a quantitative trait shows continued variation under the influence of many different genes
• Trait: Any detectable phenotypic property or character. • Qualitative trait: A genetic disease trait that either present or absent. The pattern of inheritance for a qualitative trait is typically monogenetic, which means that the trait is only influenced by a single gene. • Quantitative trait: are measurable characteristics such as height, blood pressure, serum cholesterol, and body mass index. A quantitative trait shows continued variation under the influence of many different genes
Quantitative trait: Normal distribution Height · Weight Shape Color Blood pressure metabolic activit reproductive rate Polygenes: small-but-equal effect QtL(quantitative trait loci)
Quantitative trait:Normal distribution • Height • Weight • Shape • Color • Blood pressure • metabolic activity • reproductive rate Polygenes: small-but-equal effect QTL (quantitative trait loci)
Successive approximations to a Gaussian Distribution: OTL (A)One loc (B)Two loci AaBb BB AAB aaBb 100 110 120 AaBBCC 70 110 120 (C)Three loci (D)Many loci AABBCC 708090100110120130 100 110 120
Successive Approximations to a Gaussian Distribution: QTL
Aa Genotypes A Short Tall aabb aBb aaBS A2BB AA66 abb AaBb AAb Abb Genotypes Short Tall 是 Tall carey et al: Medical Genetics, 4th Edition