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.
Cabello
P H
PH
Departamento de Genética, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil.
Krieger
H
H
D001938:Brazil; D003241:Consanguinity; D008393:Marriage; D008957:Models, Genetic; D009275:Names; D010375:Pedigree; D015203:Reproducibility of Results