Evidence from certain clinical trials and observational studies has suggested an relationship between Ig antibody levels and infection rates, as well as infection severity in patients with MS [14, 15] However, a large real world cohort study demonstrated that at least one individual hypogammaglobulinemia event occurred in 32.8% of ocrelizumab-treated patients for IgM and 21 serious infections in 266 patients occurred without any association between hypogammaglobulinemia and serious infection risk [16]. This evidence concerns the gene CD40LG and Decreased circulating immunoglobulin concentration.