To define probes within +/− 1 MB of SNPs, probes were re-annotated using ReMOAT (http://www.compbio.group.cam.ac.uk/Resources/Annotation/). Ambiguous probes that mapped to multiple positions, or were identified as having design problems in ReMOAT, were excluded from subsequent analyses. To remove potential bias resulting from polymorphisms, all probes that included an analyzed SNP within the 50mer probe were removed.