Myasthenia gravis (MG) is an acquired autoimmune disorder of neuromuscular junction characterized by the easy fatigability and weakness of the skeletal muscles in which autoantibodies mostly directed to the acetylcholine receptor (AChR) and muscle-specific kinase (MuSK) (Gilhus and Verschuuren, 2015; Sanders et al., 2016) In addition, about 10–15% double-negative MG patients have antibodies against lipoprotein-related protein 4 (LRP4) (Li et al., 2018). Here, MUSK is linked to myasthenia gravis.