An assessment of the genetic relationship between alcohol metabolism and alcoholism risk in Australian twins of European ancestry

The present analyses examined genetic influences on alcohol metabolism and their possible rela-tionship to risk of alcohol dependence. Subjects were 206 Australian twin pairs who participated in an alcohol challenge protocol in 1979-1981, in which they were given a 0.75 g/kg dose of al-cohol; blood alcohol concentrations (BACs) measured at five times over a 3-hr period after alco-hol ingestion were examined. Structural equation modeling, fitting a combined autoregressive and common factor model, indicated significant heritabilities for both men and women (h2 range = 0.19-0.71), with significant parameter heterogeneity as a function of gender. In 1992-1993, both twins from 159 of the alcohol challenge pairs completed a telephone-administered psychiatric di-agnostic interview. Repeated-measures MANOVAs were used to examine whether respondent's or cotwin's DSM-III-R alcohol dependence status, or parental history of alcohol problems, was associated with variation in alcohol metabolism. There was some evidence that individuals at in-creased genetic risk of alcohol dependence [with either a paternal history of alcohol problems (women) or an MZ male cotwin who reported a history of alcohol dependence by 1992-1993] showed lower initial BACs than other groups. However, this effect was not seen in those who themselves had a history of alcohol dependence by interview follow-up, perhaps because this re-lationship was already masked by a history of excessive drinking at baseline