Clinical and Genetic Heterogeneity in Progressive External Ophthalmoplegia Due to Mutations in Polymerase γ

Abstract

PROGRESSIVE EXTERNAL ophthalmoplegia (PEO) with multiple mitochondrial DNA (mtDNA) deletions in muscle can be inherited as a dominant or a recessive trait.^1,2 Clinical manifestations are heterogeneous and are usually more variable and severe in the recessive forms.² Besides PEO, clinical features include deafness, cataracts, depression, dysphagia, hypogonadism, neuropathy, and sensory ataxia.³ Muscle biopsy results typically show ragged red fibers and cytochrome c oxidase–negative fibers.³