Prevalence and clinical characteristics of mitochondrial tRNA leu(UUR) mt 3243 A-->G and ND-1 gene mt 3316 G-->A mutations in Chinese patients with type 2 diabetes.
OBJECTIVE: To assess the prevalence of mitochondrial tRNA leu(UUR) gene mt 3243 A-->G mutation and ND-1 gene mt 3316 G-->A mutation in Chinese type 2 diabetes. METHODS: 716 randomly selected, unrelated patients with type 2 diabetes were screened for the mutation with a PCR-RFLP technique. RESULTS: Three individuals with mitochondrial tRNA leu(UUR) gene mt 3243 A-->G 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: 1) an earlier diagnosis age of diabetes (38.0 +/- 10.1 year vs 53.4 +/- 10.0 year, P < 0.001); 2) lower Body Mass Index (BMI) (19.5 +/- 2.0 kg/m2 vs 24.9 +/- 10.9 kg/m2, P < 0.0001); and 3) lower post-challenge insulin levels (Area under the curve of insulin levels during the Oral Glucose Tolerance Test (OGTT), 2946 +/- 1647.2 microIU.ml-1 vs 7469 +/- 6647.7 microIU.ml-1, P < 0.01). ND-1 gene mt 3316 G-->A mutation was found in 16 patients with type 2 diabetes (2.2%) and 5 out 181 controls (2.7%) with normal glucose tolerance. Therefore, the frequency of the mutation was not different in 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 mt 3316 mutation and those without it. CONCLUSIONS: In this large cohort of Chinese Type 2 diabetes, the prevalence of mitochondrial tRNA leu(UUR) gene mt 3243 A-->G mutation was 0.4%, and the ND-1 gene mt 3316 G-->A mutation is a polymorphism unrelated to diabetes.