The crucial role of agrin in neuromuscular diseases has previously been shown in mouse models of spinal muscular atrophy (SMA), where agrin mRNA was shown to be mis‐spliced at pre‐symptomatic time points prior to motor neuron involvement, as well as other genes involved in developing motor circuitry (Zhang et al., 2013). Here, AGRN is linked to proximal spinal muscular atrophy.