However, a sub-study of a larger clinical trial exploring high-dose (up to 14,000 IU/day) vitamin D supplementation, as an add-on therapy to interferon beta 1a in patients with relapsing-remitting MS (RRMS), showed no difference in either IL-17 CD4+ or IFN-gamma CD4+ T cells at 48 weeks of observation [11]. This evidence concerns the gene CD4 and relapsing-remitting multiple sclerosis.