Cone Survival: Identification of RdCVF.

The foremost cause of irreversible blindness in major retinal diseases is photoreceptor degeneration. In animal models as well as in human retinal hereditary dystrophies, the mutations described since 1990 affect mainly coding sequences for structural proteins (peripherine, Rom 1) or components of the phototransduction cascade (rhodopsin, cGMP-dependent phosphodiesterase) found in the rod outer segments.1,2,3 The mechanisms leading to programmed cell death of these cells are still hypothetical.4 In addition to this direct rapid rod loss, delayed cone loss is seen in clinical situations and was described in 1978 in the "retinal degeneration" (rd) mouse model. Their loss is responsible for the major visual handicap because cones are essential for diurnal, colour and central vision.6 This secondary loss of cone photoreceptors does not have any obvious explanation since cones are generally not directly affected by the genetic anomaly found in these diseases. [ABSTRACT FROM AUTHOR]