Maternally Inherited Diabetes and Deafness in 4 Family Members with DNA Mutation and at Least 4 Generations with Suggestive Disease Phenotype

A 55-year-old woman presented at the emergency room suffering from dyspnea. Her medical history was notable for deafness, taking metformin for 30 years to treat type 2 diabetes, and depression. An analysis of the patient revealed an increase in lactate concentration (91 mg/dL, reference levels 4–20 mg/dL) and glucose (169 mg/dL). All other measurements were typical or within the reference range, including the presence of autoantibodies and insulin concentration. A chest x-ray showed cardiomegaly, and an echocardiography revealed systolic dysfunction with a severely depressed left ventricular ejection fraction with generalized hypokinesis. From this, the cardiologist diagnosed nonischemic dilated cardiomyopathy. The patientu0027s family history was revealing (Fig. 1, Table 1): her grandmother (I) and mother (II), both dead, suffered from deafness; the latter also had type 2 diabetes. Her brother (IIIb) had been diagnosed with type 2 diabetes at age 30 years after taking an oral glucose tolerance test. The patient has 2 children. The son (IVb) is deaf and has worn a hearing aid since age 20; he has been diagnosed with Wolff-Parkinson-White syndrome. Her daughter (IVa) has also been diagnosed with diabetes, which emerged during pregnancy after taking an oral glucose tolerance test. The familyu0027s history, therefore, reveals a pattern of diabetes, deafness, and cardiac abnormalities. All these pathologies had …