Complete mtDNA sequence of a patient in a maternal pedigree with sensorineural deafness

We have recently reported a novel mitochondrial point mutation at np 7445, in a maternal pedigree, many of whose members suffer from sensorineural deafness. The pattern of inheritance in this family is strongly suggestive of mitochondrial involvement, and the mutation affects a coding residue on both strands: the 3' terminal encoded residue of tRNA-ser(UCN), and the final residue of the COI stop codon. Since the change is silent in the latter case, any phenotypic effect of the mutation is likely conferred by an alteration in the translational properties of the tRNA, or in RNA processing. The novel mutation is absent from over 600 normal controls, but its significance is hard to evaluate, as it has been found, thus far, in only a single pedigree. We have now completed the mtDNA sequence from the index case in the affected family, using direct, solid-phase sequencing of PCR products.