In conclusion, in contrast to previous positive results in a zebrafish model for SMA and in the mutant SOD1G93A mouse model for ALS, our work demonstrates that loss of one EphA4 allele is not sufficient to improve the innervation of the NMJs, motor neuron survival, motor function and survival in the SMNΔ7 mouse model for severe SMA. The gene discussed is EPHA4; the disease is proximal spinal muscular atrophy.