Mutations in the OFD1 gene can be associated to a very specific phenotype as such in X-linked recessive retinitis pigmentosa (RP23) or more pleiotropic disorders such as in X-linked dominant OFD type 1, and X-linked recessive Joubert syndrome (JBTS10) and a mental retardation syndrome comprising macrocephaly and ciliary dysfunction [23]. This evidence concerns the gene OFD1 and retinitis pigmentosa 23.