Alcohol is oxidized to acetaldehyde by alcohol dehydrogenase (ADH) and cytochrome P-4502E1 (CYP2E1), and then to acetate by aldehyde dehydrogenase (ALDH). Polymorphisms of these ethanol-metabolizing enzymes may be associated with inter-individual difference in alcohol metabolism and susceptibility to alcoholic liver disease. We determined genotype and allele frequencies of ALDH2, CYP2E1, ADH2, and ADH3 in male Korean patients with alcoholic cirrhosis (n=56), alcoholics without evidence of liver disease (n=52), and nondrinkers (n=64) by using PCR or PCR-directed mutagenesis followed by restriction enzyme digestion. The prevalences of heterozygous ALDH2*1/*2 plus homozygous ALDH2*2/*2 in patients with alcoholic cirrhosis (7.1%) and alcoholics without evidence of liver disease (3.8%) were significantly lower than that in nondrinkers (45.3%). The c2 allele frequencies of the CYP2E1 in alcoholic cirrhosis, alcoholics without evidence of liver disease, and nondrinkers were 0.21, 0.20, and 0.20, respectively. Allele frequencies of ADH2*2 in the three groups were 0.78, 0.74, and 0.77 and those of ADH3*1 were 0.94, 0.98, and 0.95. Therefore, we confirmed the observation that the ALDH2*2 gene protects against the development of alcoholism. However, the development of cirrhosis in Korean alcoholic patients was not associated with polymorphisms of ethanol-metabolizing enzymes.
Adult ; Alcohol Dehydrogenase/*genetics ; Alcoholism/enzymology/genetics ; Aldehyde Dehydrogenase/*genetics ; Central Nervous System Depressants/pharmacokinetics ; Cytochrome P-450 CYP2E1/*genetics ; Ethanol/pharmacokinetics ; Gene Frequency ; Genetic Predisposition to Disease ; Genotype ; Human ; Korea ; Liver Cirrhosis, Alcoholic/enzymology/*genetics ; Male ; Middle Age ; *Polymorphism (Genetics)

BACKGROUND/AIMS: Genetic variations of ethanol-metabolizing enzymes can affect alcohol drinking behavior. The aims of this study were to investigate and compare the distributions of these genetic polymorphisms between a healthy control group and a heavy drinker group which included an alcoholic liver cirrhosis group. METHODS: Genotypes of ADH2, ALDH2, CYP2E1, and catalase were identified by polymerase chain reaction and restriction fragment length polymorphism. Genomic DNA was extracted from peripheral leukocytes in 42 healthy controls, 12 heavy drinkers, and 30 alcoholic liver cirrhosis patients. RESULTS: 1) The genotype frequencies of ALDH2 (1*1), ADH2 (1*1), CYP2E1 (c1c1), and catalase1 (TT) were 69%, 55%, 38%, and 12%, respectively in healthy Korean males. 2) There was a significant difference in the distribution of the genetic polymorphism of ALDH2 between the control group and heavy drinker group (12 heavy drinkers and 30 alcoholic liver cirrhosis patients). The genotype frequency of ALDH2 mutant, ALDH2 (1*2) and ALDH2 (2*2) in the heavy drinker group (12%) was significantly lower than that in the control group (30%). 3) We didn't find anyone with ALDH2 homozygote mutant (DD) in the heavy drinker group. 4) There was no significant difference in the distribution of genetic polymorphisms in ADH2, CYP2E1 and catalase1 between the two groups. CONCLUSIONS: These results suggest that the absence of ALDH2 mutant genotype is strongly related to heavy drinking behavior. We can not prove, however, any evidence that the polymorphisms of other ethanol-metabolizing enzymes are associated with the determination of alcohol-drinking behavior.
Adult ; Alcohol Dehydrogenase/*genetics ; Alcohol Drinking ; Alcoholism/enzymology/*genetics ; Aldehyde Dehydrogenase/*genetics ; Cytochrome P-450 CYP2E1/*genetics ; Ethanol/metabolism ; Humans ; Liver Cirrhosis, Alcoholic/enzymology/*genetics ; Male ; Middle Aged ; *Polymorphism, Genetic