ABSTRACT
Many kinds of mutations in mitochondrial [mt] DNA have been reported to be related to the development of Diabetes Mellitus [DM], this type of diabetes has also been shown to be influenced by other genetic factors and/or environmental factors. Among them, tRNALeu[UUR] and its adjacent mtDNA NADH dehydrogenase subunit 1[ND1] region within the mt genome are linked to high susceptibility to DM. A point mutation at 3243 base pair [bp] in the mt tRNA Leu[UUR] is commonly referred to as a syndrome of mitochondrial myopathy, Encephalopathy, Lactic acidosis, and Stroke-like episodes [MELAS]. In the current study, we have assessed the frequency of the A3243G in Iranian diabetic type 2 patients. DNA was obtained from peripheral leukocytes of 154 patients with diabetes Mellitus type2 [l50 with type 2 and 4 with gestational diabetes] and 40 control subjects. Insulin concentration from patients' blood was measured using Radioimmunoassay procedure. Patients showed fasting blood sugar [FBS] between 150-230 mg/dl, body mass index [BMI] between 19-32 Kg/m2 and insulin concentration 0.9-2.35 mg/ml. PCR-RFLP, single strand conformation polymorphism [SSCP] and sequencing methods were used to detect the A3243G or other mutations in the mitochondrial tRNALeu [UUR] gene. A3243G mutation was not detected in patients. SSCP results showed a new pattern of PCR product in 6 patients. The C3316T transition mutation in the ND1 mitochondrial gene was confirmed in selected samples [n=6] by sequencing. No differences were observed between the two groups for C3316T and A3243G mutations [P=0.348]. The mt C3316T mutation did not have any effect on the clinical finding of type 2 diabetes carrying this mutation. These data together with clinical characteristics of the patients may suggest that the mt C3316T mutation might be a polymorphism in the Iranian population