fat and LCLs identify only 30% of eQTLs to be common between tissues4. The basis for this specificity remains unresolved, but may relate to variation at tissue specific distal enhancers as opposed to conserved promoter elements3. Analyses performed on non-cultured primary tissue have typically used sources with a heterogeneous cell composition, such as peripheral blood mononuclear cells (PBMCs)3,11 or fat4. Whilst this provides general insights into tissue specific eQTLs, highly cell-type specific eQTLs may be missed due to signal saturation from other cell types where the eQTL is absent. This is especially pertinent in the elucidation of trans-acting eQTLs, where tissue specificity appears to be of increased relevance12.
