A single risk allele (rs3184504-T), a nonsynonymous SNP in the SH2B3 gene, exhibited the highest level of pleiotropy with concordant risk associations shared across seven autoimmune diseases (Supplementary table S4), including multiple sclerosis, psoriasis, lupus, type 1 diabetes, celiac diseases, inflammatory bowel disease and thyroiditis. Here, SH2B3 is linked to type 1 diabetes mellitus.