All DNA samples were genotyped on the Illumina Human 1M-Duo beadchip by the Center for Inherited Disease Research (CIDR) at Johns Hopkins University. After thorough genotype quality control process, 948,758 of the 1,049,008 genotyped SNPs were available for genetic analysis. Sixty-five of these genotyped SNPs fell within the region containing the CHRNA6 and CHRNB3 genes on chromosome 8. Of the 65, only SNPs with a minor allele frequency (MAF) >1% and a genotyping call rate >0.98 were considered (47 SNPs). Full details regarding the quality control procedures are provided in the data cleaning report posted on the GENEVA website (http://www.genevastudy.org/docs/GENEVA_Alcohol_QC_report_8Oct2008.pdf) and in related publications3536.
