Clinical features and outcomes of patients with muscle-specific kinase antibody-positive myasthenia gravis in Japan.

This study included 51 patients with muscle-specific kinase antibody-positive myasthenia gravis (MuSK-MG) from a Japanese multicenter survey to examine clinical features and outcomes. Median onset age was 37 years and female predominance was observed. All patients developed generalized symptoms and almost all (50/51) patients had bulbar symptoms. About half of the patients met the criteria for refractory MG. The refractory group had a lower age of onset, higher severity scores, and higher maximum daily doses of oral prednisolone compared to the nonrefractory group. The outcomes for MuSK-MG patients in Japan are not favorable, indicating the need for more aggressive treatment. • MuSK-MG was more common in females. • In MuSK-MG, female patients developed the disease at younger age than male patients. • All MuSK-MG cases were generalized MG, with almost all experiencing bulbar palsy. • The outcomes of patients with MuSK-MG in Japan were unfavorable. [ABSTRACT FROM AUTHOR]