Distribution of ADH1B, ALDH2, CYP2E1∗6, and CYP2E1∗7B genotypes in Turkish population

The most well-known metabolic pathways from ethanol to acetaldehyde include alcohol dehydrogenase (ADH) and the microsomal ethanol oxidizing system that involves cytochrome P450 2E1 (CYP2E1). Acetaldehyde is further oxidized to acetate by aldehyde dehydrogenase (ALDH). The genetic variation of ADH1B, ALDH2, and CYP2E1 is different among racial populations and cause difference in elimination rates of alcohol. The aim of this study was to determine the polymorphisms of ADH1B (rs1229984; Arg47His), ALDH2 (rs671; Glu487Lys), CYP2E1*6 (rs6413432; T7632A), and CYP2E1*7B (rs6413420; G-71T) in unrelated healthy Turkish population and compare it with other populations. ADH1B and ALDH2 polymorphisms were analyzed with an allele-specific polymerase chain reaction (PCR) assay, and CYP2E1*6 and CYP2E1*7B polymorphisms were genotyped by PCR-restriction fragment length polymorphism method. ADH1B polymorphism analysis yielded the genotype distribution as 83.9% ADH1B*1/1 and 16.1% ADH1B*1/2, and no individuals with ALDH2*1/2 and ALDH2*2/2 genotypes were found in Turkish population. The genotype frequencies for CYP2E1*6 polymorphism were found as 85.3% for homozygote common, 14.1% for heterozygote, and 0.6% for homozygote uncommon. For CYP2E1*7B polymorphism, the genotype frequencies were determined to be 86.5% G/G, 13.5% for G/T; however, no individuals with homozygote uncommon genotype were detected. According to our study results, the genotype distributions of ADH1B, ALDH2, CYP2E1*6, and CYP2E1*7B in Turkish population were similar compared with Caucasian and some European populations, whereas differed significantly from East Asian populations. This study may be useful in epidemiological studies of the influence of ADH1B, ALDH2, CYP2E1*6, and CYP2E1*7B polymorphisms on diseases, including several types of cancer related to alcohol consumption and alcohol dependence.