Among the 18 CRD genes, ten (GUCY2D, PITPNM3, GUCA1A, HRG4/UNC119, CRX, AIPL1, RIMS1, SEMA4A, PROM1 and PRPH2/RDS) are found in autosomal dominant (ad) CRD, six (ABCA4, RPGRIP1, RAX2, CORD8, ADAM9 and CERKL) in autosomal recessive (ar) CRD and two (RPGR and CACNA1F) in X-linked CRD http://www.sph.uth.tmc.edu/Retnet. Here, GUCA1A is linked to cone-rod dystrophy.