progressive external ophthalmoplegia with mitochondrial DNA deletions
progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal dominant, type 2
An autosomal dominant condition (OMIM:609283) characterised by progressive weakness of ocular muscles and levator muscle of the upper eyelid, associated in some cases with skeletal myopathy, predominantly involving axial or proximal muscles, causing abnormal fatigability and even permanent muscle weakness. Most cases of chronic ophthalmoplegia have systemic disease, including cataracts, hearing loss, sensory axonal neuropathy, ataxia, depression, hypogonadism and parkinsonism.Pathology
Ragged-red fibres and atrophy on muscle biopsy.
Molecular pathology
Caused by defects in SLC25A4, which encodes a protein that acts as a gated pore, exchanging cytoplasmic ADP with mitochondrial ATP.