Mutations in at least 14 different genes (HNF4A, GCK, HNF1A, PDX1, HNF1B, NEUROD1, KLF11, CEL, PAX4, INS, BLK, ABCC8, KCNJ11 and APPL1) have been shown to cause MODY subtypes 1–14 (1–3). Here, HNF1A is linked to MODY.