Crumbs homolog 1 (CRB1) (CRB1)

Crumbs homolog 1 (CRB1) is a transmembrane protein essential for establishing and maintaining cell polarity and structural integrity in the mammalian retina (den Hollander et al., 1999; MedlinePlus, 2022). It is primarily localized to the subapical region of photoreceptors and Müller glial cells, where it helps form the Crumbs complex and stabilizes adherens junctions at the outer limiting membrane (Quinn et al., 2018; Foundation Fighting Blindness, 2024). Mutations in the CRB1 gene lead to a spectrum of severe autosomal recessive retinal dystrophies, including Leber congenital amaurosis type 8 (LCA8) and retinitis pigmentosa type 12 (RP12), characterized by early-onset vision loss and retinal disorganization (Cremers et al., 2002; NIH, 2026). Therapeutic strategies currently under investigation focus on gene augmentation using adeno-associated viral (AAV) vectors to deliver functional CRB1 or its homolog CRB2, as well as advanced CRISPR-based gene editing techniques (Quinn et al., 2015; Jang et al., 2024). Challenges in drug development include the large size of the CRB1 gene, the need for cell-specific expression in both photoreceptors and Müller glia, and potential toxicity from protein overexpression (Wijnholds et al., 2020).

Other names

Crumbs 1Crumbs homolog 1Crumbs cell polarity complex component 1RP12LCA8

Gene augmentation (delivery of functional CRB1 or CRB2 cDNA via viral vectors) and gene editing (correction of pathogenic mutations using CRISPR-based base or prime editing) (Quinn et al., 2015; Jang et al., 2024).