 Congenital stationary night blindness has been linked with the leopard complex since the 1970s.The presence of CSNB in non-leopard breeds and horses suggested that the two conditions might be located on close, but separate genes.However, one study used ERG findings to diagnose all the homozygous "Lp" subjects with CSNB, while all heterozygotes and non-"Lp" horses were free from the disorder.