CGS NS 202 Lecture Notes - Lecture 2: Penetrance, Haemophilia, Antirrhinum
17 Oct 2017
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Many categories: mendelian: traits controlled by only 1 gene, polygenic: traits controlled by multiple genes, multifactorial: trait affected by genes and environment. Only when the environment puts you in the threshold does the risk become higher ie. If (cid:455)ou have a health(cid:455) lung that"s never been e(cid:454)posed to cigarettes or smoke, the gene for lung cancer will not activate: rare mutations with a large effect= mendelian diseases. Chronic diseases are driven by many genes but each gene exerts a small effect, only with the combo of effects do you get the full disease: common snp with high penetrance= rare. How do we measure traits: pedigree: predict according to dominant/recessive features. He is heterozygous because albino woman is aa (recessive), so the father provides aa: incomplete dominance: when heterozygous phenotype is intermediate between two homozygous phenotypes. In snapdragons, red flowers are produced by homozygous rr plants and white flowers are produced by homozygous rr plants.
