Association study of serotonin system genes in childhood-onset mood disorder

The serotonin system has been implicated in neuropsychiatric disorders, including mood disorders. We investigated polymorphisms in two serotonin-receptor genes, HTR1B and HTR2A, and the serotonin transporter (SLC6A4) in two independent samples of patients with childhood-onset mood disorders (COMD): 203 patients from Pittsburgh, USA with matched controls and 448 small families from Hungary. Case-control and family-based analyses showed no association between COMD and any of the studied polymorphisms (all P values >0.05). Haplotype analysis of SLC6A4 was also negative in both samples. Overall, the examination of genetic variants at the HTR1B, HTR2A, and SLC6A4 loci indicated no association between the selected polymorphisms and COMD.