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: chi(2) = 7.231 df = 1, p =.007; transmission disequilibrium test: chi(2) = 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.