Symptoms of cerebellar dysfunction (ataxia, dysarthria or tremor) are commonly observed in chronic progressive multiple sclerosis, and in few cases Purkinje cell loss adjacent to focal demyelinated folia has been indeed reported.48,49 Whether such focal leukocortical lesions associated with adjacent grey matter lesions can be a feature of deleterious Kir4.1 autoreactivity in humans—as observed in e1-immunized mice—will require further investigation. This evidence concerns the gene KCNJ10 and Tremor.