Abstract:

Mutations in mitochondrial DNA have been associated with a wide spectrum of clinical abnormalities. We reported here the clinical and genetic evaluations as well as mutational analysis of mitochondrial DNA(mtDNA) in a three-generation Chinese Han family with maternally transmitted hearing loss and epilepsy. Of 14 matrilineal relatives, three suffered from hearing loss, three had epilepsy, and other did not have significant clinical abnormalities. Sequence analysis of mitochondrial genome in this family identified the novel 7472delC in tRNA^Ser(UCN) and 33 variants belonging to Asian haplogroup B4b1a2. The 7472delC locates at the highly conserved residue of T-arm of this tRNA. In fact, the 7472insC at the same position of this tRNA has been associated with hearing loss and epilepsy in several genetically unrelated families. The 7472insC has been shown to lead to a failure in tRNA metabolism and mitochondrial dysfunction. Thus, 7472delC mutation, similar to 7472insC mutation, may result in the mitochondrial dysfunctions responsible for the hearing loss and epilepsy. Furthermore, none of mutation in deafness-associated GJB2 gene was detected in this Chinese family. Therefore, the 7472delC is likely a new mitochondrial mutation with hearing loss and epilepsy.