Cross-Platform Quality Control Genotyping error can be influential in the validity of the association results. In order to estimate the size of this technical error we re-genotyped 20% of GWAS samples for 20 random SNPs. From a total of 3,160 genotypes, 25 (0.7%) were called as missing with Illumina BeadArray technology and 42 (1.3%) were called as missing in the Sequenom platform. In the remaining genotypes, we found only 11 (0.3%) to be discordant between platforms.