Cone photoreceptor function loss

Cone photoreceptor function loss (cpfl1)

Mice homozygous for the cpfl1 mutation have a normal fundus. Electroretinograms of cpfl1/cpfl1 mice show no cone-mediated photoresponse but normal rod-mediated photoresponses from 3 weeks to 15 months of age. Histological results from cpfl1/cpfl1 mice at parallel ages show an overall normal retinal structure with cone photoreceptor cell degeneration. Cone cell numbers are reduced and progressively diminish with age compared to wild-type control. However, the cones remaining appear structurally normal by electron microscopy. Although cone photoreceptor cells are functionally defective at the earliest age when testing is possible, the rod photoreceptor cells and rod-mediated photoresponses are completely intact in the cpfl1 mice. The phenotypic characteristics of cpfl1 mice are similar to those observed in patients with complete achromatopsia (ACHM2, OMIM 216900).