Secondary objectives were to evaluate the safety and tolerability of vitamin D in two different regimens, to determine the extent it influences serum 25-OH-D and PTH levels and to assess the effect of vitamin D supplementation on IFN-β- treatment efficacy, determined by relapse rate and EDSS, as well as on the serum levels of cytokines associated with immune-mediated diseases such: IL17, IFNγ and IL-10, proposed to be associated with MS disease fluctuating activity [12,13]. This evidence concerns the gene PTH and myeloid sarcoma.