Chromosome 17q21, containing a cluster of five genes [GSDMA, GSDMB, ORM1‐like 3 (ORMDL3), IKAROS family zinc finger 3 (IKZF3) and zona pellucida‐binding protein 2 (ZPBP2)], was first linked to susceptibility to T1D in 2009.90, 91, 92. The gene discussed is IKZF3; the disease is type 1 diabetes mellitus.