ABSTRACT
Objective To assess the prevalence of the A to G mutation at position 3243 of the mitochondrial tRNALeu(UUR) gene in type 2 diabetes in a Chinese population. Methods We screened 716 randomly selected, unrelated patients with type 2 diabetes for the mutation with a PCR-RFLP technique. Results Three individuals with this mutation were identified, representing approximately 0. 4％ of the type 2 patients screened. Further screening of first degree relatives of these 3 patients identified another 4 affected carriers. In comparison with type 2 diabetic patients without the mutation, these 7 carriers of the mt3243 mutation had:①an earlier onset of diabetes (38. 0±10.1 yr vs 53. 4±10.0 yr, P ＜0. 001) ;②lower BMI (19.5±2.0 vs 24. 9±10. 9, P ＜0. 0001) ;and ③ lower post-challenge insulin levels (Area under the curve of insulin levels during the OGTT, 2946± 1647.2 vs 7469±6647.7, P ＜ 0. 01). In addition, we screened the same 716 patients with type 2 diabetes, as well as 181 controls with normal glucose tolerance,for a newly described mt 3316 G→A mutation. This mutation was found in 16 patients with type 2 diabetes (2.20％) and 5 controls (2.7％). Therefore, the frequency of the mutation was not different between patients and controls.Moreover, clinical characteristics such as age of onset of diabetes, BMI, and insulin levels were not different between diabetic patients with the mt3316 mutation and those without it. Concision The mt3316 G→ A mutation is a polymorphism unrelated to diabetes.