Analysis of people with CIS or MS separated into groups of those with and without detectable anti-EBV VCA IgM antibodies demonstrated that CD32b expression was significantly lower on naive, IgMhi and IgMlo MZ-like B cells in EBV VCA IgM seropositive compared with seronegative individuals (Figures 6E–G). The gene discussed is FCGR2B; the disease is myeloid sarcoma.