Integrated determinants of multiple sclerosis susceptibility: Genetics, environment, infection and the microbiota

Multiple sclerosis (MS) arises from the convergence of polygenic immune susceptibility, environmental exposures, and infectious determinants, none of which alone is sufficient for disease expression. More than 200 genetic variants contribute to MS risk, with the HLA-DRB115:01 haplotype providing the strongest effect within a broader network of immune-regulatory loci. Functional genomic evidence shows that these variants primarily influence antigen presentation and lymphocyte activation, creating