Lrp4 plays a key role in the formation and maintenance of neuromuscular synapses, as a loss of Lrp4 leads to a failure to form neuromuscular synapses, and mutations in Lrp4 or auto-antibodies to Lrp4 cause congenital myasthenia and myasthenia gravis, respectively (Shen et al., 2013; Ohkawara et al., 2014; Tsivgoulis et al., 2014). Here, LRP4 is linked to congenital myasthenic syndrome.