Medical genetics Complex disorders Lecturer: David Saffen Ph. D Laboratory for molecular neuropsychiatric Genetics Department of cellular and genetic Medicine School of Medicine, Fudan University saffen@fudan.edu.cn
Medical Genetics: Complex disorders Lecturer: David Saffen. Ph.D. Laboratory for Molecular Neuropsychiatric Genetics Department of Cellular and Genetic Medicine School of Medicine, Fudan University saffen@fudan.edu.cn
Outline A Historical background B Phenotypes in populations C Genes in populations D Mapping disease genes E Complex disorders
Outline A. Historical background B. Phenotypes in populations C.Genes in populations D.Mapping disease genes E. Complex disorders
A. Historical background · Francis Galton: normal distributions of quantitative traits Ronald A. fisher polygenic models for quantitative traits
A. Historical background • Francis Galton: normal distributions of quantitative traits • Ronald A. Fisher: polygenic models for quantitative traits
Biometrics and Mendelian genetics Francis Galton was a pioneer in using statistica methods to quantify human traits and behaviors For example he recognized that the distribution of many traits such as height, weight, intelligence closely approximate the"noma”( aka Gaussian”) distribution He also recognized that inherited traits tended to move toward average values, a phenomenon he termed, " regression to the mean Most of galton s work on inheritance was carried out before the re-discovery of Mendel's experiments Sir Francis Galton 1822-1911 The paradigm under which Galton and other (English Victorian polymath;"biometricians"worked was that inheritance of human Cousin of charles darwin traits involved the mixing or blending of factors present biometician; eugenicist) in the parents. This picture is very different from that obtained from Mendel's experiments, which implied that inherited traits are determined by discrete factors that remain unchanged from generation to generation
Biometrics and Mendelian genetics Sir Francis Galton 1822-1911 (English Victorian polymath; Cousin of Charles Darwin; biometician; eugenicist) Francis Galton was a pioneer in using statistical methods to quantify human traits and behaviors. For example, he recognized that the distribution of many traits such as height, weight, intelligence closely approximate the “normal” (aka “Gaussian”) distribution. He also recognized that inherited traits tended to move toward average values, a phenomenon he termed, “regression to the mean.” Most of Galton’s work on inheritance was carried out before the re-discovery of Mendel’s experiments. The paradigm under which Galton and other “biometricians” worked was that inheritance of human traits involved the mixing or blending of factors present in the parents. This picture is very different from that obtained from Mendel’s experiments, which implied that inherited traits are determined by discrete factors that remain unchanged from generation to generation
Normal distributions of quantitative traits and regression to the mean Mean E5E6E Mean height 2 SD below 2 SD above the meat the mean Stature(inches) SD= standard deviation
Normal distributions of quantitative traits and “regression to the mean” Mean height 45° slope SD = standard deviation