RESEARCH ARTICLE A Novel Simple Method for Determining CYP2D6 Gene Copy Number and Identifying Allele(s) with Duplication/Multiplication

Background Cytochrome P450 2D6 (CYP2D6) gene duplication and multiplication can result in ultrarapid drug metabolism and therapeutic failure or excessive response in patients. Long range po-lymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and se-quencing are usually used for genotyping CYP2D6 duplication/multiplications and identification, but are labor intensive, time consuming, and costly. Methods We developed a simple allele quantification-based Pyrosequencing genotyping method that facilitates CYP2D6 copy number variation (CNV) genotyping while also identifying allele-specific CYP2D6CNV in heterozygous samples. Most routine assays do not identify the al-lele containing a CNV. A total of 237 clinical and Coriell DNA samples with different known CYP2D6 gene copy numbers were genotyped forCYP2D6 *2, *3, *4, *6, *10, *17, *41 poly-morphisms and CNV determination