Objective To investigate the role of a potential diabetes related mitochondrial region, which includes two previously reported mutations, 3243AG and 3316GA, in Chinese patients with adult onset type 2 diabetes Methods A total of 277 patients and 241 normal subjects were recruited for the study Mitochondrial nt 3116-3353, which spans the 16S rRNA, tRNA leu(UUR) and the NADH dehydrogenase 1 gene, were detected using polymerase chain reaction (PCR), direct DNA sequencing, PCR restriction fragment length polymorphism and allele specific PCR Variants were analyzed by two tailed Fisher exact test The function of the variants in 16S rRNA were predicted for minimal free energy secondary structures by RNA folding software mfold version 3 Results Four homoplasmic nucleotide substitutions were observed, 3200TC, 3206CT, 3290TC and 3316GA Only the 3200TC mutation is present in the diabetic population and absent in the control population No statistically significant associations were found between the other three variants and type 2 diabetes The 3200TC and 3206CT nucleotide substitutions located in 16S rRNA are novel variants The 3200TC caused a great alteration in the minimal free energy secondary structure model while the 3206CT altered normal 16S rRNA structure little Conclusions The results suggest that the 3200TC mutation is linked to the development of type 2 diabetes, but that the other observed mutations are neutral In contrast to the Japanese studies, the 3316GA does not appear to be related to type 2 diabetes
