Association between polymorphisms in serotonin 2C receptor gene and attention-deficit/hyperactivity disorder in Han Chinese subjects

Abstract Attention deficit hyperactivity disorder (ADHD) is much more frequent in males than females, so several genes on the X chromosome (e.g., MAOA and MAOB) have been pursued as candidates for influencing risk for the disorder. HTR2C is also located on the X chromosome. In the current study, we examined the relationship between the C-759T and G-697C polymorphisms of HTR2C and ADHD in 488 Han Chinese families. Transmission Disequilibrium Test (TDT) analysis showed that the −759C allele, the −697G allele, and haplotype −759C/−697G were significantly over-transmitted to affected probands, while haplotypes −759C/−697C and −759T/−697C were under-transmitted. When families were divided into three subtypes according to the diagnosis of probands, the −697G allele and haplotype −759C/−697G were significantly over transmitted to ADHD-C probands, while haplotype −759T/−697C was under-transmitted to these individuals; however, no biased transmission of any allele or haplotype was observed for probands with ADHD-I, suggesting that different subtypes of ADHD have different genetic influences. Our findings highlight the need to explore the role of 5-HT2C receptor dysfunction in the pathogenesis of ADHD.