Direct one-step PCR reaction for detection of CYP2D6 poor metaboliser / Noor Nabila Ajmi

CYP2D6 is a highly polymorphic enzyme that mediates the metabolism of many currently prescribed drugs. Genetic variability within CYP2D6 results in poor (PM), intermediate (IM), extensive (EM) and ultra-rapid metabolisers (UM) of CYP2D6 substrates with PMs are at higher risk than other metabolisers of adverse reactions to these drugs. One of the most common mutant allelic variant of this gene in PMs is the *4 allele. In this study, we determined the *4 allele frequency in a random Malaysian subpopulation by using a direct one-step allele-specific PCR amplification approach in order to compare this allele frequency among Malaysian subpopulation with the previous findings on the occurrence of this allele in Malaysia Frequencies for *4 mutated allele and genotypes have been evaluated in 123 unrelated Malaysians. Genotyping has been carried out on genomic DNA by the direct one-step allele-specific PCR amplification technique. CYP2D6*4 occurred at a frequency of 16% and CYP2D6*1, 84%. The most frequent genotypes were CYP2D6*1/*J at 75.6%, 21 (17.1%) subjects had *1/*4 genotypes and 9 (7.3%) subjects had genotypes that predicted PM phenotype. This method however was unable to produce similar result as reported earlier where the *4 allele occurred at a very high frequency in this study, but further study should be carried out to increase the specificity of the PCR reaction. This method can also be commercialized as a tool for individualization of pharmacotherapy once the method is well validated as it is time saving and less prone to contamination.