The epigenetics of multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system (CNS) associated with inflammation, demyelination, and axon destruction. At present, no reliable cure is available for the disease, largely due to the complicated circumstances causing its onset. Although genetic susceptibility is now well documented, the disease is transmitted with non- Mendelian ratios and there is strong evidence of the implication of environmental factors, including an intriguing impact of latitude. Here, we will describe the disease and the mysteries associated with its onset, and then introduce some of the data suggesting that in patients with MS, chromatin structure and chromatin-dependent transcriptional regulation are out of balance. In this context, we will have a special interest for mechanisms of gene silencing relying either on DNA methylation or on binding of HP1 proteins to histone H3 methylated at lysine 9 (H3K9me). Finally, we will speculate on tracks that may improve our understanding of the disease, by taking into consideration the role of chromatin in the translation of environmental cues into gene expression.