An extremely rare multiple mitochondrial DNA deletion syndrome with markedly decreased deoxyguanosine kinase (DGUOK) activity in skeletal muscle characterized by a highly variable phenotype. Clinical manifestations include progressive external ophthalmoplegia, mitochondrial myopathy, recurrent rhabdomyolysis, lower motor neuron disease, mild cognitive impairment, sensory axonal neuropathy, optic atrophy, ataxia, hypogonadism and/or parkinsonism. The disease is progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive 4 (MONDO_0014899). Also known as: PEOB4, adult-onset multiple mitochondrial DNA deletion syndrome due to DGUOK deficiency, adult-onset multiple mtDNA deletion syndrome due to DGUOK deficiency, progressive external ophthalmoplegia with mitochondrial DNA deletions, autosomal recessive type 4.