Given the modest eQTL significance values and effect sizes from our analyses in lymphoblastoid cell lines that would not withstand multiple testing correction (Figure 1), we conducted additional studies to further assess functionality. We were able to show that 2 of the 3 initial eQTLs, rs7858819 and rs301430, are also associated with SLC1A1 messenger RNA expression in the brain with similar significance levels and the same effect direction (Figure 1 and Figure 2). These results not only strengthen the relevance of these 2 markers for SLC1A1 genetics research, but also suggest that regulation of gene expression in lymphoblastoid cell lines resembles brain regulation for this gene. This would make this readily obtainable cell line suitable for future functional and population-based analyses of SLC1A1 in a manner that has been used extensively for a related molecule, the serotonin transporter (SLC6A4).46,47 It also calls for a systematic comparison of gene expression genetics between brain tissue and lymphoblastoid cell lines now that suitable brain data sets have become available.48
