The heterozygous knockin rhodopsin alleles we have expressed at these low levels–nonmutant hRho-GFP [8], ID2-hRho-GFP [7], P23H-hRho-GFP [6], and Q344X-hRho-GFP–all cause retinal degeneration at the same slow rate as that observed in mice heterozygous for a null rhodopsin mutation, in which there is no observable decline in nuclei from 4 weeks to 6 months[17]. The gene discussed is RHO; the disease is retinal degeneration.