Objective: To search for ethnic variability in the impact of cytochrome P450 2C9 (CYP2C9) polymorphism.
Methods: CYP2C9 allelic variants related to impaired CYP2C9 metabolism were analysed in genomic DNA from 157 Spanish healthy subjects using amplification-restriction and sequencing procedures.
Results: The frequency for CYP2C9 mutated alleles is higher among the Spanish subjects analysed than that reported for other Caucasian individuals: CYP2C9*2, 0.143 and CYP2C9*3, 0.162 (P = 0.0001). Nearly 10% of the individuals studied are expected to metabolise deficiently CYP2C9 substrates.
Conclusion: In some Caucasian populations the impact of the CYP2C9 polymorphism may be much higher than that estimated from genotyping studies published to date.