A role for HHV-6 on MS pathogenesis in the brain is supported by increased frequencies and titers of anti-HHV-6 IgG (46, 47) and IgM (48) in cerebrospinal fluids of MS patients compared to controls; and oligoclonal band specificity against HHV-6 (49, 50). The gene discussed is CD40LG; the disease is myeloid sarcoma.