Gene expression in whole blood could function as biomarkers for several disease conditions such as diabetes [16] and attention deficit hyperactivity disorder [17]. Elucidation of the genetic basis affecting such gene expression may be important in uncovering the etiological factors and pathophysiology of the diseases. Taking the aforementioned issues into consideration, we have examined the correlations between the genotypes of every SNP from a genome-wide scan and the expression levels of genes in the whole blood of Japanese individuals. To avoid the influence of batch effects, which is often ignored in eQTL studies, microarray data collected in different batches were first analyzed separately and then integrated. After strict corrections for multiple testing and exclusion of potential false-positive eQTLs, we investigated whether the SNPs found to have an effect on the expression levels in whole blood also influenced the expression levels in lymphoblastoid cell lines. Public data from the HapMap project of SNP genotypes and gene expression levels in lymphoblastoid cell lines were used for the analysis.
