Objective: To conduct a descriptive study on the prevalence of relevant cytochrome P450 2C9 (CYP2C9) polymorphisms--the *2, *3, and 5' flanking region (C-1189T)--in a Spanish population using a new minisequencing fluorescent method through a multiplex single base extension (SBE) analysis.
Method: The method simultaneously and accurately genotypes the CYP2C9 polymorphisms studied and is available as a commercial protocol (SNaPshot). Various strategies, including restriction fragment length polymorphism (RFLP) and Taqman, were used to validate the methodology.
Results: The frequencies of alleles CYP2C9*2 (12%) and *3 (6.2%) were similar to those described for other Caucasian populations. The frequency of allele t at the 5' flanking region was 62%, which is close to the percentage reported in Japanese and French populations. The four haplotypes inferred in our samples and their frequencies were consistent with those reported in other studies.
Conclusion: Our results confirm previously reported Caucasian frequencies for the CYP2C9*2 and *3 alleles and, for the first time, provide data on the frequency of the CYP2C9 5' flanking region (C-1189T), a recently described polymorphism, in a Spanish population. The SBE technique detects unequivocally the three polymorphisms in a single reaction, which makes it suitable for the analysis of CYP2C9 in the many therapeutic situations in which it is involved.