RESUMEN
Depression is a disabling illness with complex etiology. While the catechol-O-methyltransferase (COMT) gene, in particular the functional Val158 Met polymorphism, has been related to depression, the mechanisms underlying this gene-disease association are not completely understood. Therefore, we explore the association of COMT Val158 Met polymorphism with depression as well as its interaction with childhood trauma in 1136 young adults from a population-based study carried out in the city of Pelotas, Brazil. The diagnosis was performed through the Mini International Neuropsychiatric Interview 5.0 (MINI 5.0), and trauma was assessed with the Childhood Trauma Questionnaire (CTQ). Total DNA was extracted and genotyped by real-time PCR, and the QTLbase dataset was queried to perform large-scale quantitative trait locus (QTL) analysis. Our research showed no direct association between the Val158 Met polymorphism and the diagnosis of depression (women: χ2 = 0.10, d = 1, p = 0.751; men: χ2 = 0.003, df = 1, p = 0.956). However, the Met-allele of the Val158 Met polymorphism modified the effect of childhood trauma in men (OR = 2.58 [95% CI: 1.05-6.29]; p = 0.038) conferring risk for depression only on those who suffer from trauma. The conditional effect from moderation analysis showed that trauma impacts the risk of depression only in men carrying the Met-allele (effect: 0.9490, standard error [SE]: 0.2570; p = 0.0002). QTLbase and dataset for Val158 Met polymorphism were consistent for markers that influence chromatin accessibility transcription capacity including histone methylation and acetylation. The changes caused in gene regulation by childhood trauma exposure and polymorphism may serve as evidence of the mechanism whereby the interaction increases susceptibility to this disorder in men.
