Research carried out with animal models by Kedzierski et al [18] studying rds and rom1 transgenic/knockout mice found that photoreceptor degeneration in peripherin/RDS-mediated RP appears to be caused by a simple deficiency of rds and rom1. Thus, below a critical threshold for the combined abundance of rds and rom1, the extent of outer segment (OS) disorganization results in clinically significant photoreceptor degeneration. This evidence concerns the gene PRPH and retinitis pigmentosa 1.