An association study between cathechol-O-methyltransferase gene and mental retardation in the Chinese Han population

Cathechol-O-methyltransferase (COMT) regulates the amount of dopamine in the prefrontal cortex (PFC). Substantial studies indicate a close relationship between COMT and several human psychotic disorders. The case–control method was used to study the association between mental retardation (MR) and genetic variants of COMT. Three single nucleotide polymorphisms (SNPs: rs4680, rs165656 and rs165774), in the cathechol-O-methyltransferase (COMT) gene, were genotyped by PCR–RFLP method. Individual SNP analysis shows significant differences only at SNP rs165656 for both genotype and allele frequency when comparing MR cases and controls (p = 0.023, 0.011, respectively). Further haplotype analysis indicates that there are two haplotype sets, rs165656–rs4680 and rs165656–rs165774, which show statistical differences between MR cases and controls (global p = 0.047, p = 0.033, respectively). Our results suggest a positive association between the genetic variants of the COMT gene and MR in the Chinese Han population in the Qinba region.