NRN1 and retinal degeneration: Global knockout of neuritin in mice accelerates retinal ganglion cell loss and retinal degeneration following optic nerve injury (Azuchi et al. 2018), while adeno-associated virus-mediated overexpression of neuritin delays retinal ganglion cell apoptosis, regenerates injured axons, and maintains retinal ganglion cell function following optic nerve injury (Sharma et al. 2015).