Molecular heterosis in metamphetamine abusers.

Objective. The aim of our study was to assess whether the catechol-O-methyltransferase (COMT) genetic background of patients dependent on metamphetamine is related to their non-abstinence in a 1-year follow-up. Methods. We examined COMT gene Val158Met polymorphism and 1-year abstinence in a group of 31 (women N=8) Czech Caucasian metamphetamine abusers (average age, 23.8±4.0years). Results. Non-abstinence was significantly (P=0.046, Fisher's exact test) associated with the heterozygous Val/Met genotype. Conclusion. The case where subjects heterozygous for a specific genetic polymorphism show a significantly greater or lesser effect for a phenotypic trait than subjects homozygous for either allele is described as molecular heterosis in the literature. We discuss several explanations and recommendations for further research.