A Case of Mitocllondrial Diabetes Complicated by Usher Syndrome

Abstract

We report a 48-year-old man with diabetes mellitus harboring mutation in mitochondrial DNA complicated by Usher syndrome. The patient reported a history of visual field loss at age 18, bilateral sensorineural deafness at age 28, and diabetes at age 35. He took medication for diabetes from age 40. At the end of February 1999, his hearing suddenly worsened and he was admitted for therapy. He had bilateral cataracts and advanced retinitis pigmentosa, making him almost blind. Audiography showed a decrease in hearing capacity to 115dB, in the left ear and 78.3dB. in the right ear. HbA1c was 9.5%. Urinary CPR excretion was 15gμ/day, and ΔCPR was 0.8ng/ml in glucagon load testing, suggesting decreased in insulin secretion.A point mutation at position 3243 in mitochondrial DNA was detected in peripheral blood leukocytes. We consider the man to be a rare case with mitochondrial diabetes complicated by Usher syndrome characterized by juvenile-onset retinitis pigmentosa and progressive sensorineural deafness.