Allele, Diplotype, and Phenotype Frequency Distribution of CYP2B6, CYP2C19, and CYP2D6 in the Han Population in North...

This large-scale retrospective study investigated the allele, diplotype, and phenotype frequencies of CYP2B6, CYP2C19, and CYP2D6 in a Han Chinese population (N > 10,000), using real-world genetic data from The First Hospital of Hebei Medical University, assessed between March 2021 and April 2025. Single-nucleotide polymorphism genotyping was performed using the Agena MassARRAY assay. CYP2D6 copy number variation (CNV) was analyzed by TaqMan real-time quantitative PCR. The sample sizes were 9729 for CYP2B6, 11,479 for CYP2C19, and 11,315 for CYP2D6, all from the Han Chinese population. The high frequencies of alleles were CYP2B6∗6 (16.19%), CYP2C19∗2 (30.36%), and CYP2D6∗10 (41.67%), with the most common diplotypes being CYP2B6 ∗1/∗6 (23.65%), CYP2C19 ∗1/∗2 (37.62%), and CYP2D6 ∗1/∗10 (16.05%), respectively. At the phenotype level, normal metabolizer was most common for CYP2B6 (57.86%) and CYP2D6 (60.50%), whereas the intermediate metabolizer phenotype was noted for CYP2C19 (44.77%). CYP2D6 CNVs included zero copies (0.43%), one copy (13.64%), two copies (83.79%), three copies (2.11%), and more than three copies (0.03%). This large-scale, real-world study of a Northern Han Chinese cohort provides a valuable pharmacogenomic reference and demonstrates the necessity of integrating CNV analysis with single-nucleotide polymorphism genotyping to ensure accurate clinical phenotyping of CYP2D6.