HLA-DRB1 and myeloid sarcoma: In Japanese patients with MS, HLA-DRB1*15:01 is associated with a higher frequency of cerebrospinal fluid (CSF) IgG abnormality, including OCBs, while DRB1*04:05 is associated with younger age at onset, lower frequency of CSF IgG abnormality, milder disease course and fewer intracortical lesions7,11,13,24.