多基因病的分子遗传学教材课程.ppt

Polygenic Disorders;Polygenic Disorders: 由两对以上等位基因和环境因素共同作用所致的疾病，称为多基因病。;Section 1 Polygenic Inheritance;一、Definition;1. Genetic basis: multiple genes ; ;二、Characteristics ;Qualitative Trait;;0~5 % 45~50 % 100 % aa Aa AA;Qualitative trait: genetic traits which are present or absent. One has the trait or not.;Quantitative Trait;130 140 150 160 170 180 190 200 Height (cm);P the tallest the shortest AABB A’A’B’B’;A’A’B’B’;P AABBCC A’A’B’B’C’C’;20;2. Hybridization of F1 of intermediate type;Section 2 Polygenic Disorders;一、Liability and Threshold Theory ;Susceptibility: characterize the genetic factors that affect the probability of multifactorial disorder.;Liability: be a measure of all of the factors that affect the probability of multifactorial disorder, both genetic (innate) and environmental.;60 50 40 30 20 10;二、Heritability;Heritability (H, h2);If H is high —— phenotypic variation is largely genetic;常见多基因遗传病和先天性畸形的患病率和遗传率 疾病与畸形 群体患病率（%） 患者一级亲属患病率 遗传率 哮喘 4.0 20 80 精神分裂症 1.0 10 80 原发性高血压 4~8 20~30 62 消化性溃疡 4.0 8 37 强直性脊椎炎 0.2 男性先证者7 70 女性先证者2 早发性糖尿病 0.2 2~5 75 迟发性糖尿病 2~3 35 冠状动脉硬化性心脏病 2.5