In this report, we screened two Tunisian families with mitochondrial diabetes for the m.3243A>G and the m.14709T>C mutations, respectively, in the tRNALeu(UUR) and the tRNAGlu genes.
The polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) and the sequence-specific primers by polymerase chain reaction (SSP-PCR) analysis in the leucocytes and the buccal mucosa in the members of the two families showed the absence of the m.3243A>G mutation and the presence of the heteroplasmic m.14709T>C mutation in the tRNAGlu gene in the two tested tissues.
We conclude that the m.14709T>C mutation in the tRNAGlu gene could be a cause of mitochondrial diabetes in Tunisian affected families. In addition, the heteroplasmic loads correlated with the severity and the onset of mitochondrial diabetes in one family but not in the other, suggesting the presence of environmental factors or nuclear modifier genes.