POLG and autosomal dominant progressive external ophthalmoplegia: POLG mutations have been linked to a continuum of overlapping phenotypes including Alpers-Huttenlocher syndrome, childhood myocerebrohepatopathy spectrum, myoclonic epilepsy myopathy sensory ataxia, ataxia neuropathy spectrum, cardiomyopathy, autosomal recessive and autosomal dominant progressive external ophthalmoplegia (arPEO and adPEO) [10].