Specifically in the case of RPGRIP1, a number of studies probed this issue of phenotypic variability in the canine model of Rpgrip1 retinal degeneration, in which different ages of onset and variable severity of disease are seen in dogs with the same RPGRIP1 mutation (Miyadera et al., 2009; Forman et al., 2016; Das et al., 2017). The gene discussed is RPGRIP1; the disease is retinal degeneration.