The mitochondrial tRNALeu(UUR) A to G 3243 mutation is associated with insulin‐dependent and non‐insulin‐dependent diabetes in a Chinese population

The mitochondrial DNA tRNA[Leu(UUR)] A to G 3243 mutation is associated with maternally inherited diabetes in Caucasians and Japanese. In a Hong Kong Chinese population we have detected the 3243 mutation in 2 of 74 unrelated subjects with well characterized insulin-dependent (Type 1) diabetes mellitus (IDDM) and 2 of 75 unrelated subjects with young onset (<35 years) non-insulin-dependent diabetes (NIDDM). The 3243 mutation has only previously been associated with IDDM in Japanese. Racial differences in association of the mitochondrial 3243 mutation with IDDM suggest the influence of other genes that may increase its diabetogenic pathogenicity in Oriental races. We also found a significant excess of maternal inheritance of diabetes in the young onset NIDDM cohort, with a ratio of diabetic mothers to fathers of 2.4:1, p < 0.005. The 3243 mutation, however, only accounts for a small proportion of the observed excess maternal inheritance, and further study is needed to search for other diabetes associated mitochondrial DNA mutations.