Enoch and her colleagues also found that the Val allele was a risk factor for smoking, but only in women.
For the current study, researchers recruited 342 (201 women, 141 men) community-based Plains American Indians, establishing their lifetime drinking and smoking histories. Additionally, five COMT loci including Val158Met were genotyped.
"There are three key findings," said Enoch. "One, Plains Indians have very different drinking patterns. Alcoholics drink heavily, but episodically yet they still meet the criteria for alcoholism."
Two, she continued, "they have a very different comorbidity. They don't smoke heavily." In statistical terms, although 62 percent of the male alcoholics and 40 percent of the female alcoholics were smokers, only 12 percent of the alcoholic men and eight percent of the alcoholic women smoked heavily.
"And three," she noted, "at least one third are social smokers who never progress to 'real' smoking, they just smoke in social settings. This may be a throwback to the traditional use of tobacco amongst American Indians."
Enoch said that this study shows how there is no such thing as an "alcoholism gene" or "alcoholism allele."
"Here you've got one gene, and in one population one allele of the gene is associated with a disease, alcoholism, yet in another population, the gene's other allele is associated with that disease," she said. "You've really got to look at the gene-environment interaction when you've got a gene like this, with two common variant
Contact: Mary-Anne Enoch, M.D.
Alcoholism: Clinical & Experimental Research