Association analysis of TPH-1 and TPH-2 genes with suicidal behavior in patients with attempted suicide in Mexican population

Abstract

Background: Suicidal behavior is a worldwide health problem. Tryptophan hydroxylase (TPH) is a rate limiting enzyme in the biosynthesis of serotonergic neurotransmission. TPH-1 and TPH-2 genes encode for TPH isoforms and have been implicated as candidate genes for suicidal behavior. The aim of this study was to evaluate the association between the genetic variants of the TPH-1 (rs21102 and 1607395) and TPH-2 (rs4290270, rs7305115 and rs1007023) genes and suicidal behavior in a Mexican population. Methods: We conducted a case-control study including 200 cases with suicide attempt and 263 controls. Patients were evaluated by a trained psychiatrist or clinical psychologists. Five polymorphisms were genotyped and assessed for allele, genotype and haplotype association with suicide attempt. Results: The rs7305115 polymorphism of the TPH-2 gene was associated with suicidal behavior in a Mexican population in genotype (χ2 = 6.02, df = 2, p = 0.04) and allele (OR = 1.39, 95%IC = 1.06–1.81, p = 0.01) frequencies. The THP-2 haplotypes GTA (χ2 = 5.68, p = 0.01) and ATT (χ2 = 5.0, p = 0.02) were associated with risk for suicide attempt. Conclusion: Our results provide evidence for an association between the rs7305115 polymorphism of the TPH-2 gene and suicidal behavior in a Mexican population. However, more studies are necessary to replicate these results using larger samples.