Alcohol dehydrogenase genotype (ADH2 and ADH3) in alcoholism of Iraqi people
AbstractObjective The polymorphic human liver enzyme alcohol dehydrogenase (ADH) is responsible for the oxidative metabolism of ethanol. Anallele encoding active form of cytosolic enzyme is known to reduce the likelihood of alcoholism in Iraqi men. The polymorphisms of ADHmodifies the predisposition to the development of alcoholism. Determination of genotypes ADH2 and ADH3 loci in alcoholic and nonalcoholicIraqi men.Method Using leukocyte DNA extraction and then amplifying by polymerase chain reaction (PCR) by using specified primers, then allelespecific primer extension and PCR-restriction fragment length polymorphism (RFLP) methods with another set of primers is employed inorder to determine the variants of ADH2 and ADH3, respectively.Results The Iraqi alcoholics had significantly lower frequencies of ADH2*2 and ADH3*1 alleles than did the non-alcoholic as comparedwith the general population of East Asians but more than in Caucasians population, suggesting that genetic variation in ADH enzymemodulating the rate of metabolism of ethanol to acetaldehyde influences drinking and the risk of developing alcoholism. The simplestexplanation of the significant lower frequency of ADH2*2 and ADH3*1 alleles among Iraqi alcoholic men is that each can produce highertransient level of acetaldehyde, which trigger aversive reactions; these alleles are less likely to become alcoholic.Conclusion This study suggests that both ADH2 and ADH3 genotypes exert an influence on alcohol metabolic rate, alcohol-flush reactionand susceptibility to develop alcoholism. ADH2 and ADH3 genotypes may have a protective role in the risk for alcoholism in Iraqi alcoholicpopulation.
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