Background: In the heterogeneous group of mitochondrial disorders, patients with the same genotype can show different phenotypes and the same phenotype can be caused by different genotypes. We describe a family with the m.14709T>C mutation and a clinical presentation of hydrops fetalis, in contrast to previous reports in which patients presented with myopathy and/or diabetes mellitus.
Aim: To identify a mutation in the mtDNA of a family with a heterogeneous clinical presentation.
Methods: Both biochemical and molecular analyses were performed.
Results: Biochemical results showed a decreased complex I and IV activity in muscle tissue of the patients. A mosaic-staining pattern for complex I in the patients' fibroblasts was revealed using immunocytochemistry. Molecular analyses identified the m.14709T>C mutation in the mitochondrial encoded tRNA(Glu) gene.
Conclusion: We report 2 siblings with the m.14709T>C mutation in the mitochondrial tRNA(Glu) gene. The first patient showed hydrops fetalis, a new presentation within the clinical spectrum of this mutation, and the other a known presentation namely mild myopathy.