As has been previously reported for complex autoimmune diseases23, we observed genes that were associated with multiple autoimmune diseases, namely T1D, Crohn’s disease (CD), and rheumatoid arthritis (RA). Interestingly, the top (genome-wide significant) PrediXcan gene for both T1D and RA, DCLRE1B, has not been previously reported (in the NHGRI catalog) in either disease, but has been linked to CD, ulcerative colitis and inflammatory bowel disease24. Lower predicted expression of DCLRE1B was associated with increased disease risk for both RA and T1D. Interestingly, higher predicted expression of DCLRE1B was nominally associated with increased Crohn’s disease risk in our PrediXcan analysis (p = 0.001). Similarly, PTPN22 was significantly (positively) associated with RA and T1D (table 1), and nominally (negatively) associated with CD (p-value = 0.017). Previous single variant analyses implicated PTPN22 with multiple autoimmune diseases including RA, T1D, CD, myasthenia gravis, and vitiligo according to the NHGRI catalog25. These results highlight the known overlap in genetic risk factors for autoimmune diseases.
