Susceptibility to methamphetamine dependence associated with high transcriptional activity alleles of VNTR polymorphism in the promoter region of monoamine oxidase A [MAOA]

Background and purpose: Monoamine oxidase A [MAOA, Xp11.3; OMIM: 309850] can modulate the level of neurotransmitters in the central nervous system. A 30 bp variable number of tandem repeat [VNTR] genetic polymorphism on the promoter region of the MAOA can modulate the transcriptional activity of the gene. Association between this polymorphism and dependency to methamphetamine was investigated

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Subjects and methods: A total of 65 methamphetamine abusers [52 males and 13 females] and 635 healthy controls [525 males and 110 females] were included in the present case-control study. Genotypic analysis for the MAOA VNTR polymorphism was determined by conventional PCR. Based on transcriptional activity of the VNTR alleles, the alleles were categorized into two classes: L allele [2R and 3R alleles] and H allele [3.5R, 4R and 5R alleles], which have low and high transcriptional activities, respectively

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Results: Our data show that the H allele significantly increases the risk of methamphetamine dependence in males [OR = 2.03, 95% CI: 1.04-3.67, P = 0.037]. The H allele seems positively associated with the risk of dependency to methamphetamine among females, but the observed OR did not reach the significance level, probability due to small sample size of the patients

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Conclusion: The present study supports the role of the VNTR polymorphism on the promoter region of the MAOA on methamphetamine dependence