In the study of congenital myasthenic syndrome due to MuSK mutation, the changes in the presynaptic morphology were assumed to reflect a disturbance in muscle-derived retrograde signals resulting from the impairment of agrin- and Dok7-induced MuSK phosphorylation (Maselli et al., 2010; Ben Ammar et al., 2013). The gene discussed is MUSK; the disease is congenital myasthenic syndrome.