HLA-DRB1 and myeloid sarcoma: The main new findings of the present study are as follows: (1) compared with HCs, CSF IgG abnormality-positive MS patients had a significantly higher frequency of HLA-DRB1*1501, whereas CSF IgG abnormality-negative MS patients had a significantly higher frequency of HLA-DRB1*0405; (2) CSF IgG abnormality-positive MS patients had a significantly higher frequency of anti-C.