Prevalence of mitochondrial tRNA gene mutations and their association with specific clinical phenotypes in patients with type 2 diabetes mellitus of Coimbatore.

The association of mitochondrial DNA mutation with type 2 diabetes mellitus (T2DM) is well established. In this study we aimed to assess the frequency of A3243G, A8296G, and other mitochondrial mutations with reference to clinical features in the diabetic population of Coimbatore, India. The study group included 150 patients (89 women and 61 men) with T2DM, whereas the control group included 100 nondiabetic people (59 women and 41 men). Genotyping was done by polymerase chain reaction followed by single-strand confirmation polymorphism method. A3243G and A8296G mutations were found to be prevalent in patients with T2DM when compared with the control group. The A3243G mutation was found in two patients, and both these patients showed similar clinical characteristics, thus representing a putative clinical subtype. A8296G mutation was detected in one patient. The same mutation was shared with his mother who was diagnosed to have diabetes mellitus (DM) with neuromuscular disorder. The siblings of the patient did not show any symptoms of DM. Lipid profile and urea and creatinine levels were found to be significantly high (10% and 0.064%) in patients with T2DM compared with control subjects. We concluded that the identification of these mitochondrial point mutations indicates a new genetic predisposition of DM in Coimbatore population.