Parra EJ, Botton MR, Perini JA, Krithika S, Bourgeois S, Johnson TA, Tsunoda T, Pirmohamed M, Wadelius M, Limdi NA, Cavallari LH, Burmester JK, Rettie AE, Klein TE, Johnson JA, Hutz MH, Suarez-Kurtz G
Pharmacogenomics 16 (11) 1253-1263 [2015-08-12; online 2015-08-12]
Extreme discordant phenotype and genome-wide association (GWA) approaches were combined to explore the role of genetic variants on warfarin dose requirement in Brazilians. Patients receiving low (≤ 20 mg/week; n = 180) or high stable warfarin doses (≥ 42.5 mg/week; n = 187) were genotyped with Affymetrix Axiom(®) Biobank arrays. Imputation was carried out using data from the combined 1000 Genomes project. Genome-wide signals (p ≤ 5 × 10(-8)) were identified in the well-known VKORC1 (lead SNP, rs749671; OR: 20.4; p = 1.08 × 10(-33)) and CYP2C9 (lead SNP, rs9332238, OR: 6.8 and p = 4.4 × 10(-13)) regions. The rs9332238 polymorphism is in virtually perfect LD with CYP2C9*2 (rs1799853) and CYP2C9*3 (rs1057910). No other genome-wide significant regions were identified in the study. We confirmed the important role of VKORC1 and CYP2C9 polymorphisms in warfarin dose. Original submitted 14 January 2015; Revision submitted 26 May 2015.