Natalizumab (NTZ) is a humanized monoclonal antibody (mAb) against the α4 subunit (CD49d) of the α4β1 (VLA-4) and α4β7 integrins that has been approved for the treatment of multiple sclerosis (MS) due to its ability to reduce disease activity and severity in patients with relapsing-remitting MS (RRMS) [1]. This evidence concerns the gene ITGA4 and relapsing-remitting multiple sclerosis.