Maternally inherited diabetes and deafness (MIDD): unusual occult exocrine pancreatic manifestation in an affected German family.

The mitochondrial (mt) 3243 DNA mutation is an underlying cause of maternally inherited diabetes and deafness (MIDD) syndrome and the syndrome of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). We report an affected German MIDD pedigree with maternal lineage over three generations. The index patient, her mother, her maternal aunt and her maternal grandmother all suffered from diabetes and premature hearing loss and were positive on testing for the mt 3243 DNA mutation. The 27-year-old index patient had a history of grand mal seizures. As sequela of abdominal ultrasound and confirmed by magnetic resonance cholangio-pancreaticography, she was diagnosed with chronic pancreatitis with pancreatic calcifications and pancreatic duct dilation, although she was completely asymptomatic and with no signs of steatorrhoea. She did not have gallstones and the common bile duct was normal. A possible etiopathogenic pathway for pancreatitis could be a suppressive effect of the mt 3243 mutation on the oxidative phosphorylation in affected mitochondria. Although pancreatitis and pancreatic dysfunction in association with the mt 3243 mutation, especially in patients with comorbidity of MELAS and diabetes, has previously been described as a rare manifestation, this case is specific because of the discrepancy of advanced morphological pancreatic alterations and complete lack of pancreatogenic symptoms.