In 40 probands with a MODY phenotype, whole-exome analysis was performed; in 138 probands, we analyzed exons and adjacent splice sites of MODY-associated genes: HNF4A, GCK, HNF1A, PDX1, HNF1B, NEUROD1, KLF11, CEL, PAX4, INS, BLK, KCNJ11, ABCC8, and APPL1. In this work, we ignored common genetic variants and did not assess their possible effects on the phenotype. The gene discussed is KCNJ11; the disease is MODY.