ABCA4 and Stargardt disease: An unbiased systems pharmacology approach was introduced to identify novel G protein-coupled receptor (GPCR) targets, adrenoceptor α 2C (Adra2c), and serotonin receptor 2a (Htr2a) for treating Abca4–/– Rdh8–/– double knockout mouse [80] which is a Stargardt disease model demonstrating light-induced rapid photoreceptor degeneration [81].