Epidemiological data clearly underline the increased susceptibility for women to develop multiple sclerosis (MS) with four times as many women have MS as men. However, the molecular basis for the observed sex difference remains unclear. Using genome-scale DNA methylation data collected on 45 German monozygotic twin pairs discordant for MS, this project aims at performing a multi-trait epigenome-wide association study with specific aim at finding the sex-dependent DNA methylation patterns for MS. The project applies different statistical and bioinformatics strategies to identify sex mediate differential methylation sites, genomic regions and biological pathways involved in the sex-dependent disposition to MS. results from the study are expected to provide novel molecular insights to MS etiology which can be useful for the prevention and treatment of the disease.