Genomic DNA was extracted from blood samples using standard phenol-chloroform procedures and was initially quantified using spectrophotometry. Prior to hybridization to the chip, all samples were re-quantified using pico-green fluorimetry and DNA quality was assessed using standard gel electrophoresis techniques; this ensured that only samples of high quality DNA were used. Automated procedures were used to hybridize the cases and controls to the HumanCoreExome-12v1_A Beadchip (Illumina Inc., San Diego CA, USA) and scanned on the Illumina HiScan platform, using standard protocols. This particular chip comprises of 547644 markers, including all the tag markers (264,909 markers) on the HumanCore beadchip, over 240,000 markers of the HumanExome chip as well as several rare variants.
