MAG and Autoimmunity: Aberrant MAG function, for example from mutations that likely cause misfolding, or anti-MAG autoimmunity, has been associated with demyelination and neurodegenerative disorders, such as corticospinal motor neuron disease also known as hereditary spastic paraplegias4, Pelizaeus–Merzbacher disease-like disorder5, demyelinating anti-MAG peripheral neuropathy6, 7 and multiple sclerosis2, 8.