A NEW MITOCHONDRIAL-DNA MUTATION ASSOCIATED WITH PROGRESSIVE DEMENTIAAND CHOREA - A CLINICAL, PATHOLOGICAL, AND MOLECULAR-GENETIC STUDY

A novel mitochondrial DNA transfer RNA mutation at position 5549 was i dentified in a patient with dementia, chorea, cerebellar ataxia, deafn ess, and peripheral neuropathy in the absence of clinical myopathy: Mu scle biopsy specimens showed ragged red and cytochrome oxidase-negativ e fibers, and reduced complex I activity on polarography. There was di ffuse neuronal loss and gliosis throughout the brain on postmortem exa mination. The heteroplasmic mutation had a widespread distribution in autopsy tissues.