Note on estimates of the inbreeding coefficient through study of pedigrees and isonymous marriages |
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Authors: | P H Cabello H Krieger |
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Affiliation: | Departamento de Genética, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil. |
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Abstract: | 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. |
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