Abcr- mice have a neo cassette replacing the promoter and exon 1 of the ATP-binding cassette, sub-family A (ABC1), member 4 (Abca4) gene, abolishing gene expression. ABCR (ABCA4) is a retina-specific protein localized in outer segment disk edges of rod photoreceptors. Mutations in ABCR have been linked to the onset of macular degenerations such as Stargardt macular dystrophy (STGD), recessive retinitis pigmentosa, recessive cone-rod dystrophy, and age-related macular degeneration (AMD). ABCR acts as a transmembrane flippase transporter for phosphatidylethanolamine (N-Ret-PE) which moves N-Ret-PE from inside of the photoreceptor disks out to the cytoplasmic surface. The retinal pigment epithelium (RPE) of the Abcr- mice accumulates of bis-retinoid-lipofuscin material, which is further amplified after supplementation with Vitamin A. The major bis-retinoid-lipofuscin pigment in the RPE of Abcr-/- mice and STGD1 patients is A2E. The knockout mice exhibit slow-photoreceptor degeneration and delayed dark adaptation following a photobleach. Abcr homozygotes null mice are viable and fertile.
Of note, this allele is also available on a congenic C57BL/6J background (Stock No. 026800).
