BIOL239 Lecture Notes - Lecture 3: Melanin, Albinism, Sickle-Cell Disease
26 Jan 2018
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Many human traits run in families; most do not show a simple mendelian pattern of inheritance. And that"s (cid:271)e(cid:272)ause most of them are multifa(cid:272)torial polygenic (influenced by more than one gene) such as eye colour. Most confirmed single gene traits in people are relatively rare, involving abnormalities that are either disabling or life threatening. Studying family genetic histories, or pedigrees, gives insight as to how mutant alleles causing abnormalities are inherited. All the following are examples of monomorphic genes (they all carry the allele for wild type) with mutant phenotypes showing pleiotropy. Sickle cell disease: abnormal hemoglobin causes anemia, blocked circulation, and increased resistance to malaria. Tay-sachs disease: missing enzyme; present in less than 1% of human population; usually die before 5-6 years old; they end up paralyzed and die. Pku: causes an amino acid to build up because its not being broken down. Albinism: missing enzyme in a pathway to melanin production and causes unpigmented skin, hair, etc.
