This alteration of mtDNA can be due to diverse genetic defects (at least 5 nuclear genes are known) but have similar clinical presentations, usually characterized by CPEO. Associated symptoms may include hearing loss, myopathy, ataxia, peripheral neuropathy, dysarthria, optic atrophy, dementia. parkinsonism, and psychiatric problems.
Muscle biopsy is required to detect the multiple mtDNA deletions and will also reveal ragged red fibers. Transmission is either autosomal dominant or autosomal recessive.