[Association between DRD2 gene polymorphisms and the dosage used on methadone maintenance treatment program].

Objective: To investigate the association between three single nucleotide polymorphism (SNP) genes DRD2 (rs1800497, rs6275, and rs1799978) and the dosage used on methadone maintenance treatment (MMT). Methods: From the methadone maintenance treatment centers, 257 MMT patients were recruited to participate in a case-control study and divided into two groups-control groups under low dosage ( n =89) and case ( n =168) group with high dosage. Quanto software was used to estimate the sample size as 180. Information related to social-demographic status, history on drug use and medication were collected. And DRD2 SNPs were genotyped to explore the relationship between polymorphism of DRD2 gene and the dosage of methadone maintenance treatment. Results: Distributions of DRD2 rs6275 between different groups were significantly different. Patients carrying TC genotype needed lower dose of methadone when compared to the patients that carrying CC genotype counterparts ( OR =0.338, 95% CI : 0.115-0.986). Patients that carrying C allele at rs6275 needed lower methadone dose than those that carrying genotype TT ( OR =0.352, 95% CI : 0.127-0.975). Distributions of genotypes, alles in the other two SNPs (rs1800497, rs1799978) were not significantly different between groups under different dosages. Conclusion: DRD2 rs6275 was associated with dosage of methadone used for the MMT patients. However, no significant associations were found between rs1800497, rs1799978 and the dosage of methadone.