Furthermore, a proportion of refractory MG patients usually presented with the debilitating weakness, frequent relapses, MuSK or LRP4 antibody positive, post-thymectomy, and/or required high-dose steroids and add-on other IS agents (Drachman et al., 2008; Suh et al., 2013). This evidence concerns the gene LRP4 and myasthenia gravis.