identified an additional eight susceptibility loci that predispose to celiac disease [20,21]. A surprising finding from this study was that seven of the eight regions contained promising candidate genes expressed in leucocytes of the immune system. This suggested the feasibility of genetical genomics approaches using peripheral blood to assess the biological function of the celiac disease associated risk variants. One goal of genetical genomics is to uncover previously unknown biological pathways. If genetic variation affects the expression of a gene in trans, this suggests a biological relationship exists between the two loci. To assess this, considerable amounts of effort have been devoted to the development and application of statistical frameworks that are capable of detecting these trans-eQTLs. However, detection of trans-eQTLs in human populations has proven less successful than in mouse, rat and plant recombinant inbred lines [13,22]. It has been suggested that the extensive genetic and environmental diversity between human individuals masks many of the existing trans-effects.
