Classification of MS patients into EBV serological groups was conducted using interpretation guidelines provided by the manufacturer (methods, Table 1), resulting in the following categories: EBV-seronegative (n = 0), primoinfection (n = 0), suspected EBV reactivation (n = 20; anti-EBNA1 IgG+ with anti-VCA IgA+, anti-VCA IgM+, or anti-EA(D) IgG+), seropositive without active EBV infection (n = 23; anti-VCA IgG+ and anti-EBNA1 IgG+), and atypical EBV reactivation (n = 8; anti-EBNA1 IgG+ and anti-EBNA1 IgM+) (Table 2). The gene discussed is CD40LG; the disease is myeloid sarcoma.