A Pediatric Case of MELAS Syndrome Associated with Insulin-dependent Diabetes Mellitus

ABSTRACT

MELAS(mitochondrial myopathy, encephalopathy, lactic acidosis, and sroke like episodes) is a major subgroup of heterogeneous mitochondrial encephalopathy. Recent advances in molecular genetics revealed specific mutations in the mitochondrial DNA causing MELAS. We described clinical and molecular genetic findings of a 13-year-old boy with MELAS syndrome associated IDDM(insulin dependent diabetes mellitus). For molecular genetic studies, DNAs from peripheral blood nucleated cells were used. And the A-->G substitution at the nt position 3,243 in the mitochodrial tRNAleu(UUR) gene in a heteroplasmic fashion was confirmed in the patient and his mother, which supporting maternal transmission. The mother had no neuromuscular syndromes but was diabetic. The islet cell antibody was abscent in both the patient and his mother, proving an indirect evidence of beta cell destruction was caused by the definite mitochondrial DNA itself. The association of MELAS syndrome and IDDM has been reported very rarely, and this is the first case report in Korea.