Early onset of diabetes mellitus associated with the mitochondrial DNA T14709C point mutation: Patient report and literature review

We report a family in which a mother and son were affected with diabetes me llitus and myopathy characterized by ragged red fibers and suggestive of mi tochondrial disease. Mitochondrial DNA (mtDNA) analysis of DNA isolated fro m peripheral blood showed a T-->C point mutation at nucleotide position 147 09, in the transfer RNA gene for glutamic acid. We review the association o f diabetes and mtDNA mutations. This child's case is unusual because of the early onset of diabetes, which is more typical of mtDNA deletions.