RP2 encodes a GTPase-activating protein (GAP) for ARL3 that regulates ciliary protein trafficking and assembly 1. RP2 functions as a molecular switch in the ARL3 signaling pathway, inactivating GTP-bound ARL3 to release cargo-carrying proteins like UNC119 for delivery to the ciliary membrane and outer segment of photoreceptors 1. This process is essential for proper localization of membrane-associated proteins, including components of heterotrimeric G proteins critical for phototransduction 1. RP2 mutations cause X-linked retinitis pigmentosa (XLRP), accounting for approximately 5.3% of early-onset severe retinal dystrophy cases in some populations 2. XLRP represents the most severe form of retinitis pigmentosa, affecting approximately 15-20% of all RP cases 3. Affected males typically experience progressive vision loss with advancing age, whereas heterozygous female carriers generally maintain relatively preserved visual acuity throughout their lifetime, though approximately 79% show funduscopic abnormalities 3. The X-linked inheritance pattern and reliance on loss-of-function mechanisms make RP2-associated disease a candidate for gene replacement therapeutics 4.