Recently, we reported that HLA-DRB1*0405 and HLA-DPB1*0301 are susceptibility alleles, while DRB1*0901 and DPB1*0401 are protective alleles for Japanese MS when neuromyelitis optica (NMO) and NMO spectrum disorder (NMOSD) patients are excluded [7]. Here, HLA-DRB1 is linked to neuromyelitis optica.