OBJECTIVETo explore the prevalence and the clinical characteristics of mitochondrial gene mutation A3243G (mt tRNA(Leu(UUR)) 3243 A-->G) in patients with type 2 diabetes mellitus (DM2) in China.

METHODSFour hundred and twenty-eight cases of DM2 patients were selected randomly. One hundred and eighty-eight individuals were healthy controls. The mutation was assayed by PCR-restriction fragment length polymorphism technique. The target fragments of PCR were digested with restriction endonuclease Apa I.

RESULTSmt tRNA(Leu(UUR)) 3243A-->G gene mutation was found in 2 of 428 patients with DM2, but not found in the controls. Further investigation of the relatives of the 2 patients' families revealed that 3 members were the carriers of mt tRNA A3243G gene mutation and the patients with diabetes. In addition, one proband and her son were characterized with the syndrome of mitochondrial encephalomyopathy with lactic acidosis. The diabetes of these patients is frequently accompanied by hearing impairment or deafness with maternal inheritance.

CONCLUSIONThe prevalence of the mitochondrial gene A3243G mutation is 0.47% in DM2 patients in China. The data acquired in this study suggest that the clinical phenotype of these patients with A3243G should be heterogeneous.