Genes that modulate susceptibility for alcohol dependence

The pathways for the metabolism of the alcohol are complex and modulated by some genes that promote response to this substance. The genes that codify the enzyme alcohol dehydrogenase (os genes ADH1B or ADH2) act in the conversion of ethanol in acetaldehyde; the enzyme aldehyde dehydrogenase (ALDH2) that converts the aldehyde into ascetic acid, and the gene that codifies the enzyme cytochrome P450, isoform 2E1 (CYP2E1), that acts generating free radicals of great importance in the induced hepatotoxicity for ethanol had been studied. The objective of this work is to present some genes that, normal or mutated, influence susceptibility to alcohol dependence. For the accomplishment of this work it was studied papers in the national bibliographical database Scielo and PubMed that report the functions of the above-mentioned genes. In one of the searched works, in a Spanish population, association was found in the polymorphism Arg47Hys in exon 3 of gene ADH1B. Genotypes contend the mutant alele ADH1B*2 had been common in non-alcoholics women, being able to indicate protection against alcoholism in the carriers of this alelle, according to author of the article. In studies in S o Paulo, -75 bp A/C and -159 bp G/A polymorphisms in the gene ADH4 (alcohol dehydrogenase type 4) had been associated with alcohol dependence, and individuals carrying the haplotypes with the alelles of risk C and A had presented odds ratio of 2.9. The interest about genetics in this area and studies of these polymorphisms in different populations are necessary for the establishment of a consensus on which of these mutations are influencing the alcohol dependence.