TPH gene polymorphism and aging: indication of combined effect on the predisposition to violent suicide

Findings relating serotonin to suicidal behavior suggest the role of genes for tryptophan hydroxylase (TPH) in the genetic substrate of this disorder. Association of Tph1 gene and suicidality, despite considerable research efforts, remains controversial. Polymorphism A218C in intron 7 of Tph1 gene was studied in violent suicide victims (N = 247) and controls (N = 320) of Slavic (Croatian) origin, with specific consideration of the influence of subjects' age. The frequency of, allegedly less active, CC genotype was increased in older (above 65 years) victims as compared to controls (P = 0.0126 and 0.0008, for comparison with age-specific and integral control samples, respectively), while there were no differences between victims under 65 years and controls. Excess of the CC genotype in elderly victims of violent suicide points to the possible combined effect of the respective genetic factor and physiological changes during aging on the predisposition to this disorder.