GUCY2D, encoding photoreceptor guanylate cyclase GC-E, is crucial in phototransduction. It synthesizes cGMP, the intracellular messenger of photoreceptor excitation, and is regulated by GCAPs [1]. Mutations in GUCY2D are associated with various retinopathies, making it a key gene in understanding retinal diseases [1,2,3,4,5,6]. Animal models, like knockout mouse and chicken models, have been used to study GUCY2D-related retinal guanylate cyclase deficiency [1].

These animal models have been instrumental in gene augmentation therapy research. For example, gene replacement therapy in knockout mouse and chicken models of GUCY2D-related deficiency showed promising results, indicating potential therapeutic approaches for human diseases [1]. In patients, mutations in GUCY2D can cause autosomal recessive Leber congenital amaurosis (LCA) and autosomal dominant cone-rod degeneration (adCRD) [1]. LCA-causing mutations often lead to reduced or absent cGMP synthesis, while CRD-causing mutations shift the Ca2+-sensitivity of the GC-E-GCAP complex [1].

In conclusion, GUCY2D is essential for normal phototransduction through its role in cGMP synthesis. Gene knockout animal models have been valuable in revealing its function and developing gene-based therapies for LCA and adCRD, highlighting the importance of GUCY2D research in understanding and treating retinal diseases.