Next-generation sequencing (NGS) has identified variations in cytochrome P450 (CYP) 2D6 associated with drug responses. However, determination of novel haplotypes is difficult because of the short reads generated by NGS. We aimed to identify novel CYP2D6 variants in the Japanese population and predict the CYP2D6 phenotype based on in vitro metabolic studies. Using a targeted NGS panel (PKSeq), 990 Japanese genomes were sequenced, and then novel CYP2D6 haplotypes were determined. K_m, V_max, and intrinsic clearance (V_max/K_m) of N-desmethyl-tamoxifen 4-hydroxylation were calculated by in vitro metabolic studies using cDNA-expressed CYP2D6 proteins. After determination of the CYP2D6 diplotypes, phenotypes of the individuals were predicted based on the in vitro metabolic activities. Targeted NGS identified 14 CYP2D6 variants not registered in the Pharmacogene Variation Consortium (PharmVar) database. Ten novel haplotypes were registered as CYP2D6*128 to *137 alleles in the PharmVar database. Based on the V_max/K_m value of each allele, *128, *129, *130, *131, *132, and *133 were predicted to be nonfunctional alleles. According to the results of the present study, six normal metabolizers (NM) and one intermediate (IM) metabolizers were designated as IM and poor metabolizers (PM), respectively. Our findings provide important insights into novel haplotypes and haplotypes of CYP2D6 and the effects on in vitro metabolic activities.

下一代测序（NGS）已确定与药物反应相关的细胞色素P450（CYP）2D6的变异。但是，由于NGS产生的短读段，很难确定新的单倍型。我们旨在鉴定日本人群中的新型CYP2D6变异体，并根据体外代谢研究预测CYP2D6表型。使用靶向NGS面板（PKSeq）对990个日本基因组进行测序，然后确定新的CYP2D6单倍型。ķ_米，V_最大和固有清除率（V_最大/ K_米的）ñ通过体外代谢研究，使用cDNA表达的CYP2D6蛋白，计算了-desmethyl-tamoxifen 4-hydroxylation。在确定CYP2D6双型后，根据体外代谢活性预测个体的表型。有针对性的NGS鉴定了14种CYP2D6变体，未在Pharmacogene Variation Consortium（PharmVar）数据库中注册。在PharmVar数据库中将10个新的单倍型注册为CYP2D6 * 12 8至* 137等位基因。基于每个等位基因的V _max / K _m值，* 128，* 129，* 130，* 131，* 132和* 133被预测为非功能性等位基因。根据本研究的结果，分别将6种正常代谢物（NM）和1种中间代谢物（IM）分别指定为IM和弱代谢物（PM）。我们的发现为CYP2D6的新单倍型和单倍型及其对体外代谢活性的影响提供了重要的见识。