Note on estimates of the inbreeding coefficient through study of pedigrees and isonymous marriages.
Crow and Mange (1965) developed a method to estimate the inbreeding coefficient (F) through an ingenious surname analysis. Such formulations assume a regularity of transmission of surnames, monophyletism, and random occurrence of consanguineous marriages. Accordingly, the ratio of isonymous partners to F of the offspring is equal to 4. Nevertheless, genealogy analyses show that the consanguineous marriages do not necessarily occur regularly. Therefore the isonymy analysis gives a misestimation of the inbreeding coefficient, depending on the prevailing form of nonrandomness. We suggest a small correction to the formulation in situations when pedigree information is available. The weighted mean of the ratio of isonymous partners to F of the known consanguineous marriages is suggested as a way to improve the formulas. The technique was applied to a northeastern Brazilian sample, and the results agree well with those of bioassays and therefore provide an apparently more realistic estimate of the inbreeding coefficient by isonymy.
Departamento de Genética, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil.
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Cabello
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Krieger
D001938:Brazil; D003241:Consanguinity; D008393:Marriage; D008957:Models, Genetic; D009275:Names; D010375:Pedigree; D015203:Reproducibility of Results