TGM2 and myasthenia gravis: In addition, transglutaminase 2 (TG2) [102], constitutive expression of c-Myb lacking its 3′ untranslated region (3′ UTR) [223], inhibition of 3-hydroxy 3-methylglutaryl coenzyme A reductase (HMGR) [225], myasthenia gravis [46], and the lack of ste20-like kinase (SLK) [221] also impair the capacity of myoblast fusion and decrease the fusion index.