Background-Oxytocin (OXT) and prolactin (PRL) are neuropeptide hormones that interact with the serotonin system and are involved in the stress response and social affiliation. In human studies, serum OXT and PRL levels have been associated with depression and related phenotypes. Our purpose was to determine if single nucleotide polymorphisms (SNPs) at the loci for OXT, PRL and their receptors, OXTR and PRLR, were associated with childhood-onset mood disorders (COMD).

Brain-derived neurotrophic factor (BDNF) polymorphisms have been examined for their contribution to depression with equivocal results. More homogeneous phenotypes might be used to improve our understanding of genetic liability to depression. The aim of our study was to 1) test for association between BDNF Val66Met polymorphism and childhood onset melancholic depression and 2) to examine the interactive effects of stressful life events (SLE) and the Val66Met polymorphism on the risk of childhood onset melancholic depression. Materials and Methods 583 depressed probands were involved in this study (162 of the melancholic subtype). Diagnoses were derived via the Interview Schedule for Children and Adolescents - Diagnostic Version and life event data were collected by means of an Intake General Information Sheet Results 27.8% of the participants met criteria for melancholy. In the melancholic group the proportion of the females was higher (53.1%), though there were more males in the overall depressed sample. We detected no significant differences in genotype or allele frequency between the melancholic and the non-melancholic depressed group. BDNF Val66Met polymorphism and stressful life event interaction was not significantly associated with the melancholy outcome. Conclusion In our study, females are more prone to develop the early-onset melancholic phenotype. To our knowledge, this is the first study to investigate the differentiating effect of the genotype and the G×E interaction on melancholic phenotype in a large sample of depressed young patients. We didn’t find association between the melancolic subtype of major depression and the BDNF genotype and stressful life event interaction in this sample, which is representative to the Hungarian clinic-referred population of depressed youths.

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