First and second degree relatives of 99 probands with affective disorders (49 unipolar and 50 bipolar subjects) were studied. The high risk values obtained for affective disorders were shown to be compatible with those found by other authors, although the prevalence of the illness in the population of Lombardy appears to be much lower than in other countries. Very low rates of suicide and alcoholism were found in our sample. Data obtained by analysis of the affected pairs of relatives rule out the hypothesis of a dominant X-linked gene if the bipolar and the unipolar forms are considered genetically separated entities. Results compatible with a polygenic condition, partially shared by bipolar patients, were found using Slater's and Smith & Falconer's methods. Our data, however, cannot rule out the dominant hypothesis.

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HLA phenotype distribution was investigated in 91 affective patients. Significant increases over those of the control population were found in HLA-A 29 and in Bw 22 frequencies, while A 10 and A 30 were decreased. No significant difference was shown between the two clinical subgroups (41 unipolar patients and 50 bipolar ones). On comparing our data with those from other authors, Bw 16 was significantly increased. However, a high degree of heterogeneity was also shown for this antigen. Of some interest is the finding that relapsed and non-relapsed patients during long-term lithium therapy display diverging HLA phenotype distributions, with B 5 increased among the non-relapsed subjects.

The authors have investigated HLA-haplotype zygotic assortment in 21 families with multiple cases of affective disorders and in 19 sibling pairs discordant for the disease. The finding of excess similarity between affected sibs stressed the possibility of the existence of genes in the HLA chromosomal region which are involved in the susceptibility to affective disorders. The mode of inheritance of such an hypothesized DS gene was also tested and some theoretical implications are discussed.

Psychiatric disorders in a sample of spouses of probands with recurrent Primary Affective Disorders (PAD) and in their first degree relatives were evaluated and compared with those in the spouse of control subjects without psychiatric illnesses. No differences were found in the risk for PAD, but spouses of PAD patients and their respective first degree relatives manifested a greater incidence of affective spectrum disorders.