CRB1 and retinal degeneration: We also tried a native occurring short version of the CRB1 protein encoded by a CRB1 cDNA lacking exons 3 and 4 while maintaining the open reading frame, but whereas the short CRB1 (sCRB1) was expressed, it also caused retinal degeneration upon subretinal injection of the AAV9-CMV-sCRB1 or AAV9-hGRK1-sCRB1 [24].