HMB265H1 Chapter : 5.4 Human Pedigree Analysis
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HMB265H1 Full Course Notes
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Pedigree analysis: deducing single-gene inheritance of human phenotypes by a study of the progeny of matings within a family, often stretching back several generations. Propositus: in a human pedigree, the person who first came to the attention of the geneticist. Usually the phenotype in the propositus is exceptional in some way. Disorder appears in progeny of two unaffected parents. Inbreeding increases the chances that two heterozygotes will mate. In human pedigrees, an autosomal recessive disorder is generally revealed by the appearance of the disorder in the male and female progeny of unaffected parents. Normal allele is recessive, defective allele is dominant. Pedigrees of mendelian autosomal dominant disorders show affected males and females in each generation thy also show affected men and women transmitting the condition to equal proportions of their sons and daughters. Polymorphism (morphs): the occurrence in a population of several phenotypic forms associated with alleles of one gene or homologs of one chromosome.
