HLA system and affective disorders: a sibship genetic study.

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.