Type 1 diabetes is a chronic autoimmune disorder with onset usually in childhood92. The λs for T1D is ~15 and twin data suggest that over 85% of the phenotypic variance is due to genetic factors93. There are six genes/regions for which there is strong pre-existing statistical support for a role in T1D-susceptibility: these are the major histocompatibility complex (MHC), the genes encoding insulin, CTLA-4 (cytotoxic T-lymphocyte associated 4) and PTPN22 (protein tyrosine phosphatase, non-receptor type 22), and the regions around the interleukin 2 receptor alpha (IL2RA/CD25) and interferon-induced helicase 1 genes (IFIH1/MDA5)94. However, these signals can explain only part of the familial aggregation of T1D. Five of these previously identified associations were detected in this scan (P≥0.001) (Table 2 and Supplementary Table 10), the exception being the INS gene discussed above.
