A case of mitochondrial DNA A3243G mutation presenting with renal complications and hearing impairment as the main clinical manifestations.

Abstract

A 33-year-old woman with proteinuria was admitted to our hospital for a renal biopsy. She had suffered from slight hearing impairment since she was 15 years old. Pure-tone audiometry revealed bilateral mild sensorineural hearing loss. Although renal biopsy revealed evidence of IgA nephropathy, the clinical features of this patient were not typical of this disease, as the proteinuria was not associated with hematuria. Genetic analysis of mitochondrial DNA revealed the A3243G mutation. Electron-microscopic observation of the kidney biopsy specimen revealed abnormal structures of the mitochondria. When we see patients with sensorineural hearing loss associated with unexplained proteinuria, this type of mitochondrial disease should be considered in the differential diagnosis, even in the absence of a history of diabetes mellitus.