Common to both cell types, we observed a trans-eQTL to DEF8 (rs2760985 pmonocyte=9×10−17 pB-cell=6.2×10−13) (Figure 5c), a chromosome 16 encoded gene expressed in peripheral blood mononuclear cells of unknown function41. This association resolves to presence of the DQA1*0301 allele. These novel trans-associations to class II MHC alleles represent the first observations of differential expression of genes defined in trans by the presence of specific HLA alleles. Whilst it is unclear whether these molecular signatures are causative or arising from the disease risk associated HLA alleles, these trans-associations provide original insight into the mechanistic basis of the MHC and disease susceptibility.
