RP1 (RP1 axonemal microtubule associated) is a microtubule-associated protein essential for photoreceptor cell development and maintenance. The protein regulates the stability and length of microtubule-based axonemes in photoreceptors and plays a critical role in organizing the outer segments of rod and cone photoreceptors, ensuring proper orientation and stacking of outer segment disks. RP1 mutations are a significant cause of inherited retinal diseases, particularly retinitis pigmentosa (RP). In Japanese populations, RP1 is among the six most frequently mutated genes causing RP, accounting for a substantial portion of cases 1. The gene shows population-specific variant patterns, with the c.2614dupC (p.Arg872fs) variant being particularly prevalent in Japanese patients with autosomal dominant RP 1. Additionally, RP1 variants, including c.5797C>T, are associated with autosomal recessive macular dystrophy and cone-rod dystrophy 2. Large-scale genetic studies consistently identify RP1 as responsible for 1.8-3% of inherited retinal disease cases 3 4. The protein's dysfunction leads to progressive retinal degeneration, making RP1 mutations clinically significant for genetic counseling and potential therapeutic interventions in retinal dystrophies.