The second dataset consists of controls from the National Institute of Mental Health Center for Collaborative Genetic Studies on Mental Disorders (http://www.nimhgenetics.org/). A total of 418 subjects (controls) were genotyped using both the Affymetrix GeneChip Mapping 500 K Array Set and the Illumina HumanHap 550 K Array set and passed all cleaning procedures. All individuals in this study were European Americans with no evidence of heterogeneity, verified by principal component analysis[17]. All SNPs with a genotype call rate <95% were removed, as well as SNPs with a Hardy-Weinberg exact p value <1×10−5. After quality control, 447,250 autosomal SNPs were retained from the Affymetrix 500 K array, and 527,095 autosomal SNPs were retained from the Illumina 550 K array.
