More than 40 genes have been identified to cause RP, of which 20, 26, and two genes were responsible for adRP, arRP, and xlRP, respectively (RetNet, the Retinal Information Network, provided in the public domain by the University of Texas Houston Health Science Center, Houston, TX, accessed March 7, 2010). The gene discussed is PLIN2; the disease is retinitis pigmentosa 1.