Estimating the parameters of the incompletely penetrant single locus model using multiple populations.

A method involving the comparison of two or more populations is suggested as a means of obtaining a unique solution to the parameters of the incompletely penetrant single locus model. The proposed method allows a test of the assumptions of the model when three or more populations are compared. Equations that allow the inclusion of data on twin concordance rates and/or the proportion of affected children given neither, one or both parents affected are also given. Finally, some implications of fitting the model are discussed in terms of genetic counseling, residual environmental variance and the concept of heritability as applied to dichotomous traits.