Mitochondrial DNA A3243G mutation in patients with early- or late-onset type 2 diabetes mellitus in Hong Kong Chinese

BACKGROUND AND OBJECTIVES The mitochondrial DNA A to G mutation at nucleoti de 3243 (mt3243) is associated with a subtype of diabetes characterized by maternal transmission and deafness. We have previously reported a 2.7% prev alence of this mutation in a cohort of young patients with either type 1 or type 2 diabetes. In this study, we aimed to confirm this finding by examin ing for the prevalence of this mutation in a large-scale study. SUBJECTS AND METHODS Nine hundred and six unrelated Chinese patients with t ype 2 diabetes and 213 nondiabetic controls were studied. The presence of m t3243 mutation was determined by polymerase chain reaction amplification an d Apal digestion. RESULTS This mutation was found in four of 133 (3.0%) patients with early o nset (less than or equal to 40 years) diabetes who also had a positive mate rnal family history, and in one of 348 (0.3%) patients with late-onset (les s than or equal to 40 years) diabetes and no family history. Basal pancreat ic beta-cell function, as assessed by fasting plasma C-peptide, was variabl e amongst mutation carriers, and did not correlate with the level of hetero plasmy of mutation. CONCLUSIONS In agreement with most studies, our results suggest that despit e the high prevalence of positive maternal family history of diabetes among st our type 2 diabetic patients, mt3243 mutation was not a major cause of d iabetes in either early- or late-onset diabetic patients in Hong Kong, The role of other genetic, environmental and intrauterine factors needs further investigation.