What is true for retinal disease genes in general is especially true for RP. Currently, mutations in 17 different genes are known to cause adRP,mutations in 25 genes cause recessive RP, mutations in 13 genes cause recessive LCA, mutations in 2 genes cause dominant LCA, and mutations in 6 genes cause X-linked RP.1Table 2 lists the genes that are currently known to cause nonsyndromic,nonsystemic RP. However, a simple listing of genes in each category is misleading because many genes can cause more than 1 form of disease. For example, although rhodopsin mutations usually cause dominant RP, other rare rhodopsin mutations cause recessive RP. Mutations in NRL can also be either dominant or recessive acting. Further, mutations in some genes, such as RDS, can cause dominant RP, dominant macular degeneration,or other distinct forms of retinopathy. Therefore, Table 2 also lists the alternate phenotypes that can arise for mutations in RP genes and lists some genes in more than 1 section.