POLYMORPHISM OF ADH AND ALDH GENES AMONG 4 ETHNIC-GROUPS IN CHINA ANDEFFECTS UPON THE RISK FOR ALCOHOLISM

The alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs) that metabolize ethanol are polymorphic, Different alleles encode subu nits of the enzymes that differ in their rate of metabolizing ethanol, These polymorphisms are distributed differently among populations and have been shown to influence the risk for alcoholism in some Asian po pulations, We have examined the allele frequencies at the ADH2, ADH3, and ALDH2 loci in four populations from China (Han, Mongolian, Korean, and Elunchun) and in alcoholics within each population, The four popu lations differ in allele frequencies, with the Elunchun having a much lower frequency of ADH22 alleles, and the Mongolian and Elunchun havi ng a much lower frequency of ALDH22 alleles, Within each population, alleles at one or more of these three loci are protective against alco holism, although the populations differ in which loci play significant roles, The protective allele at each locus (ALDH22, ADH2*2, and ADH3 1) encodes a subunit that either metabolizes ethanol to acetaldehyde more rapidly or slows the conversion of acetaldehyde to acetate, Taken as a whole, data demonstrate that genetic differences in the enzymes that metabolize alcohol can substantially affect the risk for alcoholi sm.