Genetic polymorphism of liver alcohol dehydrogenase in Spanish subjects: significance of alcohol consumption and liver disease.

Class I alcohol dehydrogenase (ADH) phenotypes have been studied by starch gel electrophoresis and activity analysis in liver tissue obtained at necropsy from 61 non-alcoholic subjects with normal liver (controls), and in biopsies from 60 chronic alcoholics with liver disease and from 24 subjects with non-alcoholic liver disease. Twenty-three per cent of controls exhibited the ADH2 phenotype, which represents the highest frequency for atypical ADH found in a Caucasian population. Both alcoholic and non-alcoholic patients with liver disease showed a lower frequency of the atypical phenotype (6.6% and 8.8%, respectively). No differences in the ADH2 locus were detected among groups of patients with different severity of alcoholic and non-alcoholic liver disease. The allele frequencies of the ADH3 locus for the controls (ADH3 = 0.63, ADH3 = 0.37) are common to those of other Caucasian populations. Similar ADH3 allele frequencies were observed in patients with alcoholic and non-alcoholic liver disease. Discrepancies between the various phenotyping and genotyping studies now known for several populations suggest that local differences may exist in the distribution of the ADH polymorphism in even geographically close regions, and that the effect of ADH polymorphism on vulnerability towards alcohol may not be identical in different populations.