The risk of type 1 diabetes (T1D) is higher in patients with IPEX (FOXP3, forkhead box P3), WHIM syndrome, autoimmune polyglandular syndrome type 1 (APS type 1 due to AIRE mutation), CTLA4 mutation, deficiency of LRBA, milder forms of ADA deficiency, and STAT1 GOF. This evidence concerns the gene FOXP3 and type 1 diabetes mellitus.