NMNAT1 is indispensable for mouse development (Conforti et al., 2011) and recent studies identified causative mutations in NMNAT1 in patients with Leber congenital amaurosis type 9 (LCA9), a disorder associated with severe, early-onset retinal degeneration and vision loss (Falk et al., 2012; Perrault et al., 2012; Koenekoop et al., 2012; Chiang et al., 2012; Coppieters et al., 2015; Khan et al., 2018). This evidence concerns the gene NMNAT1 and Leber congenital amaurosis 9.