The role of OPRM1 polymorphism in the etiology of alcoholism.

BACKGROUND: Numerous studies have investigated the association between the OPRM1 A118G polymorphism (rs1799971) and alcohol dependence, but the results have been inconsistent. The endogenous opioid system has been implicated in the development of alcohol dependence for its prominent role in the central rewarding mechanism.

OBJECTIVES: The aim of this study was to evaluate the role of the A118G polymorphism of the OPRM1 gene in the pathogenesis of alcohol dependence syndrome (ADS).

MATERIAL AND METHODS: The OPRM1 (rs1799971) polymorphism was investigated in an association study of a group of ADS patients (n = 177) and in subgroups (delirium tremens and/or seizures, age at onset <26 years, dissocial alcoholics, positive familial history of alcoholism, delirium tremens, and seizures). The control group consisted of healthy volunteers, with matched gender and age, and with psychiatric disorders excluded (n = 162).

RESULTS: Our research shows that there are differences in the genotypes and alleles of the OPRM1 polymorphism in the case-control study. Furthermore, we observed associations in our homogeneous subgroups - in the group of patients with ADS and accompanying delirium tremens and/or seizures at the genotype level, as well as in the subgroup of patients under 26 years of age with an early onset of dependence.

CONCLUSIONS: It is strongly possible that the G allele described in numerous studies can be associated with a response to treatment, but not typology, or the very predisposition toward alcoholism. It is necessary to carry out further research which would embrace a larger group of patients; it should be divided into other homogeneous subgroups, including, e.g., naltrexone pharmacotherapy.