[Mitochondrial DNA 3243, 3316 point mutations and type 2 diabetes mellitus]

To investigate the prevalence of mitochondrial DNA (mtDNA) mutation at position 3243(A/G) and 3316(G/A) in Chinese patients with type 2 diabetes mellitus.

Two hundred and twenty-five unrelated Chinese patients with type 2 diabetes and 195 nondiabetic control individuals without family history of diabetes in Yunnan were examined. The presence of mt 3243 and 3316 mutations was determined by polymerase chain reaction amplification and restriction fragment length polymorphism (PCR/RFLP). Finally, mutant mtDNA was confirmed by DNA sequencing.

The mitochondrial DNA mutation at position 3316 was found in 5 of 225 (2.22%) patients with type 2 diabetes, and this mutation was found in 2 of 195 (1.03%) control individuals. There was no significant difference in respect to the frequency of the mutation between patients and controls. The mitochondrial DNA mutation at position 3243 was not found in any of the patients and controls.

The results suggest that the prevalence of the mitochondrial tRNA (Leu(UUR))gene at position 3243(A/G) mutation is so low that it may not be a major cause of type 2 diabetes mellitus in patients of Yunnan, China, and the mitochondrial ND1 gene at position 3316(G/A) mutation may be a polymorphism unrelated to diabetes in Chinese. The role of other genetic, environmental and intrauterine factors needs further investigation.