Lack of Association of Alcohol Dependence and Habitual Smoking With Catechol-O-methyltransferase

Objective: To test whether variation in the gene encoding the enzyme catechol-O-methyltrans-ferase (COMT), which catalyzes the breakdown of dopamine and other catecholamine neurotrans-mitters, is associated with the risk for alcohol dependence and habitual smoking. Methods: Single nucleotide polymophisms (SNPs) were genotyped in a sample of 219 multiplex alcohol-dependent families of European American descent from the Collaborative Study on the Genetics of Alcoholism (COGA). Family-based tests of association were performed to evaluate the evidence of association between the 18 SNPs distributed throughout COMT, including the functional Val158Met polymorphism, and the phenotypes of alcohol dependence, early onset alco-hol dependence, habitual smoking, and comorbid alcohol dependence and habitual smoking. Results: No significant, consistent evidence of association was found with alcohol dependence, early onset alcohol dependence, habitual smoking or the comorbid phenotype. There was no evi-dence that the functional Val158Met polymorphism, previously reported to be associated with these phenotypes, was associated with any of them. Conclusion: Despite the substantial size of this study, we did not find evidence to support an association between alcohol dependence or habitual smoking and variation in COMT