Although we did not find clear associations in the GWAS data, the physiologic trait ‘lymphocyte count’ does exhibit evidence of heritability (H2 = 0.41 in our GWAS population), implying that genetic variation explains nearly half of the phenotypic variation. We reasoned that some fraction of this genetic variation is likely to be regulatory in nature, as has been the case for most studied complex traits to date. Therefore, in parallel to the GWAS, we conducted a gene expression study in order to identify gene regulatory differences that are correlated with variation in lymphocyte counts across individuals.
