Dharam P. Agarwal

Distribution of ADH2 and ALDH2 genotypes in different populations

SummaryThe distribution of the human liver alcohol dehydrogenase, ADH2, and aldehyde dehydrogenase, ALDH2, genotypes in 21 different populations comprising Mongoloids, Caucasoids, and Negroids was determined by hybridization of the amplified genomic DNA with allele-specific oligonucleotide probes. Whereas the frequency of the ADH12allele was found to be relatively high in the Caucasoids, Mexican Mestizos, Brazilian Indios, Swedish Lapps, Papua New Guineans and Negroids, the frequency of the ADH22gene was considerably higher in the Mongoloids and Australian Aborigines. The atypical ALDH2 gene (ALDH22) was found to be extremely rare in Caucasoids, Negroids, Papua New Guineans, Australian Aborigines and Aurocanians (South Chile). In contrast, this mutant gene was found to be widely prevalent among the Mongoloids. Individuals possessing the abnormal ALDH2 gene show alcohol-related sensitivity responses (e.g. facial flushing), have the tendency not to be habitual drinkers, and apparently suffer less from alcoholism and alcohol-related liver disease.

Racial differences in alcohol sensitivity: a new hypothesis.

SummaryA hypothesis regarding alcohol sensitivity in Japanese due to a polymorphism of liver aldehyde dehydrogenase (ALDH) is presented. ALDH was found to show two major bands, a faster migrating isozyme with a low Km for acetaldehyde and a slower migrating isozyme with a high Km for acetaldehyde. Out of 40 livers of Japanese, 21 had only the slower migrating isozyme. No such variation was detected in 68 autopsy livers of Germans. Our data suggest that the initial alcohol sensitivity, quite common in individuals of Mongoloid origin, might be due to a delayed oxidation of acetaldehyde rather than its higher than normal production by atypical alcohol dehydrogenase.

Electrophoretic and biochemical studies of human aldehyde dehydrogenase isozymes in various tissues

Abstract Four major ALDH isozymes have been identified in human tissues using starch gel electrophoresis and isoelectric focusing. The isozyme bands have been termed as ALDH I, II, III and IV according to their decreasing electrophoretic migration and increasing isoelectric point. The isozymes have been partially purified via preparative isoelectric focusing. Kinetic characteristics of ALDH I and II were found to be quite similar to ALDH enzyme 2 and enzyme 1 described earlier by Greenfield and Pietruszko (Biochem Biophys Acta, 483 35–45 1977). ALDH III and IV showed a very high Km for propionaldehyde (1.0–1.5 mM at pH 9.5) and were not inhibited by disulfiram at pH 9.5. A variant phenotype of ALDH which lacked in isozyme I was detected in various tissues from Japanese individuals. Comparative kinetic properties of normal and variant enzyme are given.

Aldehyde dehydrogenase isozyme variation and alcoholism in Japan.

Aldehyde dehydrogenase (ALDH) isozyme composition in hair roots was determined using isoelectric focusing in 105 healthy individuals, 175 alcoholics, 86 schizophrenics and 47 drug dependents. The incidence of ALDH isozyme I deficiency in healthy populations in Japan was found to be about 40%. Among alcoholics, however, only 2.3% individuals had the isozyme deficiency. There was no difference between normal controls, schizophrenics and drug dependents regarding the incidence of ALDH isozyme I deficiency. These observations indicate a possible protective role of ALDH isozymes against alcoholism. The higher frequency of ALDH isozyme I deficiency in Japanese may explain why alcoholism in Japan has been less frequent than in European and North American countries. ALDH isozyme II was found in most of the tissues and erythrocytes. A higher frequency of individuals possessing lower ALDH activity in hemolysates was observed in alcoholics than that in controls. The activity of acid phosphatase was also reduced in alcoholics. Alcohol abuse might result in disturbed protein synthesis in the erythrocytes.

Liver glutathione S-transferase polymorphism in Japanese and its pharmacogenetic importance

SummaryA total of 168 autopsy liver extracts from Japanese individuals were examined for the glutathione S-transferase (GST) isozymes by means of starch gel electrophoresis. The gene frequencies of GST1*1, GST1*2, and GST1*0 in Japanese were 0.252, 0.057, and 0.691, respectively. GST1*3 was detected as a rare variant allele. The incidence of GST1 0 in 41 liver biopsy samples from patients suffering from various liver diseases was investigated using polyacrylamide gel isoelectric focusing. The GST1 0 phenotype was found more frequently in livers with hepatitis and carcinoma than in control livers. The isozymes coded by different GST loci were partially purified and characterized to study their biochemical properties. The apparent Km values with 1-chloro-2,4-dinitrobenzene (CDNB) as substrate for the isozymes at the GST1, GST2, GST3, and GST4 loci were 604, 1345, 776 and 591 μM, respectively.

Isozyme variations in acetaldehyde dehydrogenase (E.C.1.2.1.3) in human tissues

SummaryNAD-dependent acetaldehyde dehydrogenase (ALDH) of human tissues was investigated by electrophoresis and enzyme assay. ALDH is located mainly in the liver and kidney. The isozymes consist of at least six different components. Five different phenotypes were found in a total of 68 human liver and kidney specimens. It is likely that three isozyme sets are concerned in determining ALDH types. The distribution of various phenotypes of ALDH isozyme sets is presented.

Genotyping of mitochondrial aldehyde dehydrogenase in blood samples using allele-specific oligonucleotides: comparison with phenotyping in hair roots

SummaryDeficiency of mitochondrial aldehyde dehydrogenase (ALDH I) is an inborn error of metabolism that is responsible for acute alcohol sensitivity (flushing response) observed only in Orientals of Mongoloid origin. Our previous studies using electrophoretic enzyme detection have shown that this deficiency is prevalent among Japanese, Chinese, and other Orientals. We report here the genotyping of ALDH I locus in blood samples of 218 South Korean individuals by means of hybridization analysis with allele-specific oligonucleotide probes and enzymatically amplified human genomic DNA. The results of genotyping are compared with the phenotype analysis in hair roots of the same individuals. Among 62 apparently deficient phenotypes, 58 heterozygote and 4 homozygote deficient genotypes were observed.

Alcohol metabolizing enzymes: studies of isozymes in human biopsies and cultured fibroblasts.

Rapid and sensitive micromethods for the study of alcohol dehydrogenase and aldehyde dehydrogenase isozymes in skin extracts, cultured fibroblasts and other organs are presented. Possibilities for the application of these techniques to the study of interindividual variations in response to alcohol are discussed. While fibroblasts cultured from a skin biopsy from one Japanese individual revealed a heterodimer (ADH22‐1) of alcohol dehydrogenase, skin extract from another Japanese showed a homodimer (ADH22‐2). Up to four isozyme sets for aldehyde dehydrogenase (ALDH) were detected in various human organs and at least three sets were found in skin and fibroblast extracts. Our preliminary data on liver, stomach, and skin indicate that ALDH is polymorphic and several loci are concerned in the determination of these isozyme sets.

Aldehyde Dehydrogenase Polymorphism and Alcohol Metabolism in Alcoholics

Significant differences in the incidence of aldehyde dehydrogenase isozyme I deficiency were observed between healthy controls and alcoholics in Japan. Only about 5% of alcoholics were found deficient as compared to about 42% in the normal healthy population. Blood acetaldehyde level after alcohol drinking was also found significantly higher in deficient subjects than in individuals without deficiency. Among alcoholics, deficient subjects showed relatively less elevated blood acetaldehyde levels. When two districts in Japan were compared, per capita alcohol consumption correlated with the frequency of isozyme deficiency. Higher percentage of aldehyde dehydrogenase isozyme deficiency was associated with lower per capita alcohol consumption. Thus, individuals deficient in aldehyde dehydrogenase isozyme may consume less alcohol.

Inheritance of mitochondrial aldehyde dehydrogenase: genotyping in Chinese, Japanese and South Korean families reveals dominance of the mutant allele

SummaryGenotyping of mitochondrial aldehyde dehydrogenase (ALDH I) was performed in enzymatically amplified DNA of 20 Chinese, Japanese and South Korean families (85 individuals) and in 113 unrelated persons by employing allele-specific oligonucleotide probes and dot blot hybridization. Genotyping individuals with phenotypic deficiency of ALDH I activity always showed the presence of at least one mutant allele. The data are compatible with a model assuming dominant inheritance of the mutant allele, which we have previously suggested on the basis of a population study.