Transmission of affective disorders: an application of segregation analysis to blind family study data

The single major locus (SML) model of Bucher and Elston (1981) was applied to data collected in a long-term follow-up and family study of major effective disorders. Pedigree segregation analysis was used to test the hypothesis that bipolar and unipolar disorders are phenotypic variants of the same genotype at a SML. The particular SML model examined did not adequately describe the familial pattern of these disorders in families of bipolar and unipolar probands. Although other SML models may be superior, it is likely that the existence of a SML will be obscured by genetic heterogeneity.