Mutations in mitochondrial DNA (mtDNA) were found to be associated with hypertension. We reported here clinical, genetic and molecular characterization of a Han Chinese family with maternally inherited hypertension. Most strikingly, this family exhibited a high penetrance of hypertension. Sequence analysis of the entire mitochondrial genome showed the presence of the well-known T4363C mutation in tRNAGln, as well as the ND1 T3394C mutation, and a set of polymorphisms belonging to human mitochondrial haplogroup M7b. Of these, the T4363C mutation was localized at the highly conserved nucleotide in the anticodon stem of tRNAGln (position 38), may result the failure in tRNA metabolism. Moreover, the homoplasmic ND1 T3394C mutation, which had been reported to be associated with Leber\'s hereditary optic neuropathy (LHON), was regarded as a pathogenic mutation associated with mitochondrial diseases. Thus, the combination of ND1 T3394C and tRNAGln T4363C mutations may contribute to the high penetrance and expressivity of hypertension in this Chinese family.

BACKGROUND: Leber\'s hereditary optic neuropathy (LHON) is a mitochondrial disorder with optic nerve atrophy. Although there are no other associated neurological abnormalities in most cases of LHON, cases of \"LHON plus\" have been reported.
METHODS: The proband was a 37-year-old man who had visual and gait disturbances that had first appeared at 10 years of age. He showed horizontal gaze palsy, gaze-evoked nystagmus, dysarthria, and cerebellar ataxia. Brain and orbit MRI disclosed atrophy of the optic nerve and cerebellum, and degenerative changes in the bilateral inferior olivary nucleus. Mutational analyses of mitochondrial DNA identified the coexistence of heteroplasmic G11778A and homoplasmic T3394C mutations.
CONCLUSIONS: These results suggest that the combination of G11778A and T3394C mutations leads to an atypical LHON phenotype.