NRXN2 and proximal spinal muscular atrophy: Interestingly, a reduction or altered Nrxn2 splicing have been observed in both transgenic SMA mice and zebrafish [42], while in vitro studies in motor neurons derived from SMA patients’ iPSCs showed a reduction of NRXN2 expression compared to controls, while an overexpression of NRXN2 improved the SMA motor neuron survival, and increase neurite length, suggesting it might act as a gene modifier in SMA [43].