Optimization of pyrosequencing method for copy number analysis of CYP2D6

CYP2D6, a member of the cytochrome P450 enzyme system, has a central role in drug metabolism, it metabolizes 25 % of clinically used drugs. The gene that codes for the enzyme displays a high degree of polymorphism, which effects enzyme functions to various degrees. Aside from smaller mutations like SNPs, alleles may also feature duplications or deletion of the whole gene. Due to the clinical relevance of these mutations, a simple and precise method for genotyping is needed. In this study, a method based on pyrosequencing for copy number analysis was evaluated, wherein the copy number was determined by relative quantification to a reference gene CYP2D8P. During evaluation of the method, several adjustments were tried for optimization, including adjustments of annealing temperature and primer concentration. The results showed a difficulty in distinguishing between copy numbers using the method, as well as a high coefficient of variation. Therefore, further optimization is required before the method could be implemented into clinical practice