CD4 and myeloid sarcoma: DNA methylation is probably the best explored of the three main epigenetic processes, and aberrant methylation in gene regulator regions may underlie processes involved in MS onset.119 While methylation changes have been reported in MS at HLA‐DRB1 in CD4+ but not CD8+ T cells,120, 121 in brains,122 and in relapsing‐remitting versus primary progressive MS,123 it is unclear if these changes are drivers or responses to the disease.