TPH2 variant rs7305115 and its interaction with acute stressful life events in etiology of suicide attempt in Serbian psychiatric patients

Abstract

Introduction: Suicide attempt (SA) is in the middle of continuum of complex suicidal behavior phenotype. Psychiatric disorders and acute stressful life events (SLEs) are triggers for suicidal behavior. Serotonin system genes are often implicated in suicidal behavior. Tryptophan hydroxylase 2 (TPH2), exclusively expressed in the brain, is the rate-limiting enzyme for serotonin biosynthesis. TPH2 may be enrolled in stress-response mechanisms via hypothalamic–pituitary–adrenal axis, while TPH2 variant rs7305115 has been reported to affect gene expression in postmortem human pons. To date, only poor examination of this variant in etiology of suicidal behavior has reported conflicting results. The aim of the present study was to assess rs7305115 main effect and its interaction with acute SLEs in SA pathology among Serbian psychiatric patients. Methods: 165 suicide attempters and 188 suicide non-attempters, suffering from major psychiatric disorders, participated in the study. Acute SLEs score was assessed using the List of Threatening Experiences Questionnaire. Variant rs7305115 was genotyped using TaqMan-based allelic discrimination assay. Statistical analyses were done in SNPstats by applying logistic regression adjusted by psychiatric diagnoses. Results: Variant rs7305115 was not associated with SA in Serbian psychiatric patients, neither alone, nor in combination with acute SLEs, for all five models of inheritance tested (P>0.05). Discussion: Our finding does not support the main and moderating implication of TPH2 variant rs7305115 in SA liability among Serbian psychiatric patients. Further examination in larger samples of this variant in SA patology is necessary due to its functional relevance.