Genetics and the environment (Vitamin D) converge to dysregulate N-glycosylation in multiple sclerosis : Nature Communications : Nature Publishing Group

Susceptibility genes (IL2RA ,  IL7RA and CTLA4 ) and the protective environmental factor, Vitamin D3, pivot around a see-saw that  controls the activity  of a glycosylation enzyme, MGAT1 , whose increased activity decreases the risk of developing multiple sclerosis , with decreased activity increasing risk.
MGAT1 regulates autoimmunity via T cell modulation Grigorian et al, 2007 and other mechanisms are discussed in this key paper

Multiple sclerosis genes risk factors and pathways