from living in a family environment that includes a severely ill family member. If replicated by future work, our empirical molecular genetic evidence of a partly shared genetic etiology for schizophrenia and major depressive disorder would have key nosological and research implications, incorporating major depressive disorder as part of a broad psychiatric genetic spectrum. A shared genetic etiology for bipolar disorder and major depressive disorder has been shown in family studies2,3, but the rg SNP value of 0.47 was lower than the estimate of 0.65 from a twin study55.
