PRKG1 and Splenomegaly: IRAG1 and PKGIβ expression largely overlap at the protein level [5], and IRAG1 mutant mice have a similar phenotype, e.g., the dilatation of the gastrointestinal tract [4,8], reduced gastrointestinal motility [4] and bleeding (Section 2.1, Figure 1) similar to the global Prkg1-KO mice [9], and it is known that Prkg1-deficient mice develop splenomegaly [10,12].