Determination of -3858G-->A and -164C-->A genetic polymorphisms of CYP1A2 in blood and saliva by rapid allelic discrimination: large difference in the prevalence of the -3858G-->A mutation between Caucasians and Asians.

Introduction: Two mutations in CYP1A2, -164C-->A (allele CYP1A2*F) and -3858G-->A (allele CYP1A2*C), affecting the inducibility of the enzyme, have been published. The aim of this study was to develop a high throughput allelic discrimination assay for these mutations in both saliva and blood and to determine their frequency in Caucasians.

Methods: An allelic discrimination assay, based on the fluorogenic 5'-nuclease activity (TaqMan), was developed for the two mutations. Genomic DNA extracted from 17 saliva and 100 blood samples from Caucasians was analysed.

Results And Conclusions: For the -164C-->A mutation, we found an allelic frequency of 68% in the Caucasian population, comparable with data published for Asians and Caucasians. For the -3858G-->A mutation, the allele frequency was only 2% in Caucasians, a much lower value than the approximately 25% reported in Asians (P<0.001). The presented allelic discrimination allows fast and accurate detection of these two mutations. Genotype calls were 100% identical for DNA from saliva and blood. Saliva is easily accessible and represents an excellent alternative to the traditionally used venous blood for genotyping.