In the preschool group, 32.4% of the isolated IRDs were related to forms of Leber’s congenital amaurosis (most frequent were RPE65 (11%) and CEP290 (8.2%)), 31.5% were related to stationary IRDs, 15.1% were related to macular dystrophies (ABCA4, BEST1, PRPH2, PROM1), and 8.2% to rod–cone dystrophies (RPGR, RPB3, RP2, PDE6A). The gene discussed is PDE6A; the disease is Leber congenital amaurosis.