Differences in alcoholism rates exist between Indo- and Afro-Trinidadians. We investigated whether these differences are explained by variations in the genes encoding the alcohol-metabolizing enzymes alcohol dehydrogenase and aldehyde dehydrogenase.

ADH1B, ADH1C, ALDH1 and ALDH2 polymorphisms were determined as well as serum alanine aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase and gamma-glutamyl transpeptidase levels.

Forty-four percent of Indo-Trinidadians had one ADH1C∗2 and one ADH1C∗1 allele and 5 percent were homozygous. Twenty-three percent of Afro-Trinidadians had one ADH1C∗2 allele and 1 percent were homozygous. The allele was associated with alcohol dependence. Alcoholics with at least one ADH1C∗2 allele had elevated levels of alkaline phosphatase and gamma-glutamyltransferase. Forty-one percent of the Afro-Trinidadians had at least one ADH1B∗3 allele, and three were homozygous. One Indo-Trinidadian had at least one ADH1B∗3 allele. Subjects with at least one ADH1B∗3 allele were less likely to be alcohol dependent and had lower alcohol consumption levels. Among alcohol dependent subjects, ADH1B∗3 was associated with significantly higher levels of aspartate aminotransferase. None of the subjects carried the ALDH2∗2 allele. About 10 percent of the people studied carried one copy of the ALDH1A1∗2 allele. Indo-Trinidadians with at least one ALDH1A1∗2 allele were more likely to be alcohol dependent.

The presence of ADH1C∗1 in Indo-Trinidadians and ADH1B∗3 in Afro-Trinidadians is associated with reduced risk for alcoholism. The presence of at least one copy of the ALDH1A1∗2 allele was found to be associated with an increase in alcohol dependence in Indo-Trinidadians.