MUSK and myasthenia gravis: These subgroups include AChR antibody‐positive generalized, ocular or thymoma‐associated myasthenia gravis, MuSK (muscle‐specific tyrosine kinase) and LRP4 (low density lipoprotein receptor‐related protein 4) antibody‐positive myasthenia gravis, and seronegative myasthenia gravis.