Do People Who Have Lost Their Vision to LCA Still Have Salvageable Photoreceptors?
Report from the annual ARVO (Association for Research in Vision and Ophthalmology) meeting
May 1, 2011 - We now know that many different genetic mutations can cause Leber congenital amaurosis (LCA) and other retinal degenerative diseases. With your support, an FFB-funded scientist – Dr. Robert Koenekoop, of the McGill University Health Center – has played an important role in identifying these mutations. He and his collaborators have discovered several previously unknown genetic causes of LCA, retinitis pigmentosa and Usher syndrome.
Knowing exactly which mutations are responsible for these disorders is the essential starting-point for developing safe and effective treatments. However, such treatments will require knowing how each of these mutations affects the cells of the retina; and about this, much more remains to be learned.
At the ARVO meeting, Dr. Koenekoop and his research colleagues in the Netherlands, Drs. Anneke den Hollander and Frans Cremers, presented results showing how the different mutations causing LCA affect the photoreceptors and the structure of the retina. Nearly 20 such mutations have already been identified. Although it is thought that most retinal degenerative disorders eventually destroy the photoreceptors, it is still uncertain how long the photoreceptors remain intact but inactive, when the genetic defects start to cause visual impairment.
The human participants in this study had severe vision loss, due to mutations in the GUCY2D, SPATA7, RPE65 and LRAT genes. Despite this, the research team found that in some of them, many photoreceptors were structurally sound and able to process nutrients normally. This team has already begun to study a number of other LCA gene mutations and hopes to be able to define more clearly how long the photoreceptors survive after the onset of vision loss, with each type of mutation.
Knowing whether the photoreceptors have been completely lost, or are still present but not functioning properly, will be critical for designing and applying appropriate therapies. The longer these cells remain intact, the longer people may benefit from some new therapies that are being developed. For example, Dr. Koenekoop is leading a study of a new drug therapy for LCA caused by two of these mutations (RPE65 and LRAT). Early results of this trial will also be released at the ARVO ARVO conference later in the week.
ARVO Presentation
In Vivo Retinal Architecture and Retinal Function Correlations in Specific LCA Genotypes. Presented Sunday May 1, 2011.Mahshad Darvish-Zargar, Sulaiman Al-Humaid, Amer Omer, Leah Wood, Anneke den Hollander, Frans P. Cremers, Robert K. Koenekoop.McGill University Health Center, Montreal and Radboud University Nijmegen Medical Centre, The Netherlands