GRM6 and retinal degeneration: We have previously demonstrated that the intravitreal injection of AAVs carrying the Opto-mGluR6 optogene under the control of the ON-BPC-specific GRM6 promoter (Hulliger et al., 2020) can restore visual function in otherwise blind retinal degeneration (rd1) mice (van Wyk et al., 2015; Kralik and Kleinlogel, 2021).