The possible mode of genetic transmission of depressive disease (primary unipolar affective disorder) was studied using a computationa model for the analysis of inheritance patterns devised by Slater. Detailed analyses of the occurrence of certain psychiatric disorders (depressive disease, alcoholism, and sociopathy) among secondary relatives of rigorously defined depressive probands were conducted for the probands as a group, as well as for subgroups based on age of onset, sex, and the types of psychiatric illnesses found in their families. Independent observations have suggested that genetic factors may be involved in the etiology of depressive disease. If genetic factors are involved, these data suggest that polygenic, rather than dominant gene, transmission, is the most likely possibility for both the entire proband group and for the various subdivisions.
Baker M, Dorzab J, Winokur G, Cadoret R. Depressive DiseaseEvidence Favoring Polygenic Inheritance Based on an Analysis of Ancestral Cases. Arch Gen Psychiatry. 1972;27(3):320-327. doi:10.1001/archpsyc.1972.01750270030004