Gene and environment interaction in familial suicidal behavior. A single family with 4 committed suicides.

Family history of suicide is among the strongest predictors of suicide risk. From the context of gene by environment interactions, this manuscript presents a case study of the M family, which experienced 4 committed suicides within a short time period. Over the course of 5 years, the father and 3 sons committed suicide. Suicidal ideations developed in several other members of the family. The family's suicide risk appears to have stemmed from both environmental and genetic factors, and likely from an interactive effect between both. Environmental factors included low level of education, opium dependency among male family members, unemployment, and poverty, and limited access to mental health services. Genotype analyses of A218C polymorphism among surviving family members revealed that all individuals were associated with the gene variation genotypes CC and AC in tryptophan hydroxylase. The genetic by environmental interaction influence is discussed.