CNGB1 and retinitis pigmentosa 1: Loss of photoreceptors in Cngb1–/– dogs and mice occurs more slowly than it does in some other RP models (e.g., those with phosphodiesterase 6 mutations [ref. 47]), and for this reason, treated animals need to be maintained for adequate periods of time after initiation of therapy to allow for assessment of the structural preservation resulting from therapy.