In this study, the authors investigated tryptophan hydroxylase (TPH) & suicide completion. A sample of 101 suicide completers were genotyped at 3 TPH loci in the promoter region & one in intron 7, A218C, & compared to 129 psychiatrically normal living controls. Although no significant differences were found between groups for genetic variation at single loci, haplotype analysis revealed 1 haplotype was significantly more frequent among suicide victims than in the controls. Further analysis suggested this haplotype is particularly more frequent among subjects who completed suicide using violent methods. These findings replicate those in a previous study of suicide attempters (Rotondo et al, 1999). (24 refs.)