Double-heterozygous mutations involving both HNF1A (MODY3) and HNF4A (MODY1) genes: a case report

Abstract We describe the first MODY case with mutations involving both HNF4A and HNF1A genes. History and Examination. A male patient was diagnosed with diabetes at age 17; the metabolic control rapidly worsened to insulin requirement. At that time no relatives were known to be affected by diabetes, which was diagnosed years later in both parents (father at age 50, mother at age 54) and the sister (age 32 during pregnancy). Investigations. The genetic screening showed a double heterozygosity for the mutation p.E508K in HNF1A/MODY3 gene and the novel variant p.R80Q in HNF4A/MODY1 gene. The genetic testing of the family showed that the father carried the MODY3 mutation while the mother, the sister and her two children carried the MODY1 mutation. Conclusions. MODY1 and MODY3 mutations may interact by chance to give a more severe form of diabetes (younger age at presentation, early need of insulin therapy to control hyperglycemia).