Compound heterozygous POLG1 mutations have also been recently identified in a 4-year-old child with presumed acute disseminated encephalomyelitis (ADEM) (Harris et al., 2010), and in two patients in their thirties presenting initially with unilateral optic neuritis, which subsequently evolved into clinically-definite MS with classical white matter MRI abnormalities and unmatched CSF oligoclonal bands (Echaniz-Laguna et al., 2010). Here, POLG is linked to acute disseminated encephalomyelitis.