Pharmacogenomics: accessing important alleles by imputation from commercial genome-wide SNP arrays.

Personalized medicine is becoming a medical reality, as important genotype-phenotype relationships are being unraveled. The availability of pharmacogenomic data is a key element of individualized care. In this study, we explored genotype imputation as a means to infer important pharmacogenomic alleles from a regular commercially available genome-wide SNP array. Using these arrays as a starting point can reduce testing costs, increasing access to these pharmacogenomic data and still retain a larger amount of genome- wide information. IMPUTE2 and MaCH-Admix were used to perform genotype imputation with a dense reference panel from 1000 Genomes data. We were able to correctly infer genotypes for the warfarin- related loci VKORC1 and CYP2C9 alleles *2, *3, *5, and *11 and also clopidogrel-related CYP2C19 alleles *2 and *17 for a small sample of Brazilian individuals, as well as for HapMap samples. The success of