Footnotes

• Twitter @MatsumotoY10

• Contributors YM: design and conceptualised study; analysed the data; drafted the manuscript for intellectual content. TM: design and conceptualised study; drafting and revision of manuscript. SM: data collection and analysis for MRI images. YT, SN, HK, JF and IN: data collection and analysis. TT: data collection and analysis for antibody testing. KF: design and conceptualised study; drafting and revision for intellectual content. MA: drafting and revision for intellectual content.

• Funding This work was supported by JSPS KAKENHI Grant Numbers 19K07953 and 17H04192.

• Competing interests YM reports no disclosure. TM received speaker honoraria from Tanabe Mitsubishi Pharma, Novartis Pharma., Alexion Pharma., Viela Bio., and Biogen Idec Japan, and received research support from Cosmic Corporation; and received grant-in-aid for scientific research from Ministry of Education, Culture, Sports, Science and Technology. SM reports no disclosure. YT reports no disclosure. SN reports no disclosure. HK reports no disclosure. TT received speaker honoraria from Biogen Idec and Cosmic Corporation and received research support from Cosmic Corporation. JF reports no disclosure. IN received travel funding and speaker honoraria from Biogen Japan, Tanabe Mitsubishi, and Novartis Pharma; is on the editorial board for Multiple Sclerosis International; and received research support from LSI Medience Corporation. KF serves on the advisory boards for Bayer Schering Pharma, Biogen Idec, Mitsubishi Tanabe Pharma Corporation, Novartis Pharma, Chugai Pharmaceutical, Ono Pharmaceutical, Nihon Pharmaceutical, Alexion Pharmaceuticals, and Medimmune; has received travel funding and speaker honoraria from Bayer Schering Pharma, Biogen Idec, Eisai, Mitsubishi Tanabe Pharma Corporation, Novartis Pharma, Astellas Pharma, Takeda Pharmaceutical Company Limited, Asahi Kasei Medical Co., Daiichi Sankyo, and Nihon Pharmaceutical; is on the editorial board for Clinical and Experimental Neuroimmunology; is an advisory board member for Sri Lanka Journal of Neurology; and received research support from Bayer Schering Pharma, Biogen Idec Japan, Asahi Kasei Medical, The Chemo-Sero-Therapeutic Research Institute, Teva Pharmaceutical, Mitsubishi Tanabe Pharma, Teijin Pharma, Chugai Pharmaceutical, Ono Pharmaceutical, Nihon Pharmaceutical, Genzyme Japan, Ministry of Education, Science and Technology of Japan, and Ministry of Health, Welfare and Labor of Japan. MA received research support from Japanese Ministry of Health Labor and Welfare, Japanese Ministry of Education, Culture, Sports, Science and Technology.

• Provenance and peer review Not commissioned; externally peer reviewed.

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