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 relationship to risk of alcohol dependence. Subjects were 20 6 Australian twin pairs who participated in an alcohol challenge protocol i n 1979-1981, in which they were given a 0.75 g/kg dose of alcohol; blood al cohol concentrations (BACs) measured at five times over a 3-hr period after alcohol ingestion were examined. Structural equation modeling, fitting a c ombined autoregressive and common factor model, indicated significant herit abilities for both men and women (h(2) 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 diagnostic interview. Repeated-measures MANOVAs were used to ex amine 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 increased g enetic risk of alcohol dependence [with either a paternal history of alcoho l problems (women) or an MZ male cotwin who reported a history of alcohol d ependence by 1992-1993] showed lower initial BACs than other groups. Howeve r, this effect was not seen in those who themselves had a history of alcoho l dependence by interview follow-up, perhaps because this relationship was already masked by a history of excessive drinking at baseline.