Maternally inherited hearing loss in a large kindred with a novel T7511C mutation in the mitochondrial DNA tRNASer(UCN) gene

Abstract

Article abstract Thirty-six of 43 maternally related members of a large African American family experienced hearing loss. A muscle biopsy specimen from the proband showed cytochrome c oxidase (COX)-deficient fibers but no ragged-red fibers; biochemical analysis showed marked reduction of COX activity. A novel T7511C point mutation in the tRNASer(UCN) gene was present in almost homoplasmic levels (>95%) in the blood of 18 of 20 family members, and was also found in lower abundance in the other two. Single-fiber PCR showed that the mutational load was greater in COX-deficient muscle fibers. The tRNASer(UCN) gene may be a “hot spot” for mutations associated with maternally transmitted hearing loss.