The NR2E3 gene encodes an orphan nuclear receptor in retinal photoreceptor cells, a ligand-dependent transcription factor. The NR2E3 protein is part of a large family of nuclear receptor transcription factors that regulate signaling pathways involved in embryonic development and the maintenance of normal cellular function in adults. As a transcription factor, NR2E3 acts as an activator of rod cell development and an inhibitor of cone cell development, binding to the promoter regions of several rod- and cone-specific genes, including rhodopsin (RHO), M- and S-cone opsins (OPN1MW/OPN1SW), and the rod-specific phosphodiesterase beta subunit (PDE6B) ^[1]. NR2E3 enhances the expression of rhodopsin and inhibits the expression of M- and S-cone opsins. Mutations in the NR2E3 gene are associated with Enhanced S-Cone Syndrome (ESCS) and retinitis pigmentosa (RP). Under normal conditions, the retina contains “red,” “blue,” and “green” cone cells, allowing people to see colors correctly. In ESCS, there are more blue cone cells than normal, and the rod cells, as well as the red and green cone cell receptors, degenerate. Patients often present with night blindness during childhood, with other symptoms including accommodative esotropia, nystagmus, decreased visual acuity, day blindness, and retinal lesions. Most patients have coin-shaped pigment changes along the vascular arcades and yellow-white subretinal lesions in the posterior pole, which later progress to more typical pigmentary lesions ^[2].

This strain is a mouse Nr2e3 knockout model that uses gene editing technology to knock out the homolog of the human NR2E3 gene in mice. The absence of the Nr2e3 gene in mice can lead to the appearance of pathological retinal spots, late-onset retinal degeneration, reduced ERG amplitude in rod cells, and folding and vortices in the photoreceptor layer ^[3-4]. The Nr2e3 KO mice can be used as a model for enhanced S-cone syndrome (ESCS) research.