A case-control and family-based association study of the 5-HTTLPR in pediatric-onset depressive disorders

Background Pediatric depression can be particularly informative for clarification of the causes of mood disorders. The aim of this work was to explore the possible association between childhood- and early-adolescent-onset DSM-IV depressive disorders (DD; including major depression and dysthymia) and the serotonin transporter-linked promoter polymorphism (5-HTTLPR) locus. Methods The case–control sample consisted of 68 unrelated patients with DD, and 68 unrelated age- and gender-matched healthy control subjects. The same patients were included in the family-based study, which consisted of 41 triads and 11 dyads. Results An excess of the SS-genotype (p = .025) and of the S-allele (p = .021) was found among DD children (odds ratio = 1.81; 95% confidence interval = 1.12–2.94). The family-based results suggested that the S-allele was preferentially transmitted to depressed children (haplotype-based haplotype relative risk: χ2 = 7.231 df = 1, p = .007; transmission disequilibrium test: χ2 = 5.233, df = 1, p = .022). Conclusions A role for the 5-HTTLPR locus that needs replication in larger samples is suggested in childhood DD.