Single-Step Assays to Analyze CYP2D6 Gene Polymorphisms in Asians: Allele Frequencies and a Novel *14B Allele in Mainland Chinese

genase 2D6 (CYP2D6) activity can be estimated by investigating the metabolism of model drugs or by genotyping the most common CYP2D6 alleles. For Cau-casians, the CYP2D6 allele frequencies are well investi-gated, and single-step assays are available for genotyp-ing, whereas allele analysis in mainland Chinese is limited. Methods: Two tetra-primer assays and one allele-spe-cific amplification assay were developed to easily geno-type the CYP2D6 alleles *8, *10, and *14 previously detected in Asians. Applying these assays in combina-tion with established single-tube assays, we analyzed 223 DNA samples from Chinese volunteers for the CYP2D6 alleles *3, *4, *5, *6, *8, *10, and *14 and for duplication of CYP2D6. Results: Six different alleles were detected in mainland Chinese. The most frequent mutant allele was the inter-mediate metabolizer allele, CYP2D6*10, with a preva-lence of 51.3%, followed by the poor metabolizer alleles CYP2D6*5 (7.2%) and a novel variant of CYP2D6*14. This novel *14B allele (2.0%) differs from the *14 allele by the absence of the C188T substitution and by the additional G1749C substitution. Furthermore, six dupli-cation alleles of CYP2D6 were detected, including one duplication of the *10 allele (*10X2). Conclusions: The CYP2D6 allele frequencies in main-land Chinese shows some genetic diversity compared with Chinese from other regions: a novel *14B allele, a slightly higher frequency of the *5 allele, and a slightly lower frequency of the *10 allele than in most other Chinese populations