Background: The serotonin system has been implicated in neuropsychiatric disorders, including mood disorders.
Methods: 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.
Results: 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.
Conclusions: Overall, the examination of genetic variants at the HTR1B, HTR2A, and SLC6A4 loci indicated no association between the selected polymorphisms and COMD.