Abstract
We report on a family with diabetes mellitus associated with a mitochondrial DNA mutation. The proband (21 yrs, M), his sister (14 yrs) and mother (49 yrs) developed diabetes at the ages of 21, 9 and 35, respectively. At the onset of their disease all 3 patients' fasting plasma glucose levels were elevated to between 250 and 400 mg/dl, and insulin was eventually prescribed. After one and a half months, with improvement in his metabolic abnormalities, the proband could discontinue insulin.
All patients had proteinuria at the onset of diabetes. Retinopathy was not present. In addition, the proband had hypofunction of the parathyroid glands, short stature, decreased intelligence and impaired hearing. The sister had short stature, decreased intelligence, patent ductus arteriosus and minor external anomalies. Her serum concentration of Ca was decreased and P was increased. The GH responses to provocation tests were normal in both the proband and his sister. These clinical abnormalities were not observed in the mother.
A DNA analysis using circulating white blood cells revealed an A to G transition at nucleotide 3243 in the mitochondrial tRNA Leu (UUR) in these 3 patients, with a minimal level of defective DNA in the mother.
