Prevalence of polymorphisms in the human UDP-glucuronosyltransferase 2B family: UGT2B4(D458E), UGT2B7(H268Y), and UGT2B15(D85Y).

UDP-glucuronosyltransferases (UGTs) of the UGT2B family conjugate steroid hormones as well as bile acids and xenobiotics. UGT2Bs are expressed in numerous human tissues, such as skin, breast, prostate, adipose, and intestine and are hypothesized to modulate steroid metabolism and excretion. Polymorphisms have been identified that may modify substrate specificities or enzyme activities of UGT2B family isozymes. We determined the prevalence of the UGT2B4(D458E), UGT2B7(H268Y), and UGT2B15(D85Y) polymorphisms in a sample of 233 individuals. The allele frequencies were significantly different (P < 0.02) between individuals of Caucasian and Asian descent for all three polymorphisms. In Asians (n = 32), the frequencies of the UGT2B4(D458), UGT2B7(H268), and UGT2B15(D85) alleles were 1.00, 0.73, and 0.64, respectively, whereas, in Caucasians (n = 202), the frequencies of UGT2B4(D458), UGT2B7(H268), and UGT2B15(D85) were 0.75, 0.46, and 0.45, respectively. The distribution of the UGT2B4(D458E), UGT2B7(H268Y), and UGT2B15(D85Y) genotypes also differed by ethnic group (P < 0.0001, P = 0.002, and P = 0.02, respectively). All Asians were homozygous for UGT2B4(D458) and had a greater than 2-fold higher prevalence of the UGT2B7(H268) and UGT2B15(D85) homozygous genotypes compared with Caucasians: 56.2% versus 21.8%, and 46.9% versus 22.3%, respectively. Concomitantly, only 9.4% of Asians were UGT2B7(Y268) homozygous and 18.7% were UGT2B15(Y85) homozygous compared with 29.2% and 32.2%, respectively, of Caucasians. The data suggest that there may be large differences in UGT2B polymorphisms between Asians and Caucasians. This warrants evaluation both in larger, multiethnic cohorts and in relation to known ecological differences in risk of sex hormone-dependent cancers.