Abstract
Abstract: :
Purpose:To understand the consequences in man of mutant NR2E3, a photoreceptor transcription factor, by studying the histopathology of a human retina with the enhanced S cone syndrome (ESCS) caused by the most common NR2E3 mutation, R311Q. Methods: A cohort of 16 ESCS patients with the R311Q NR2E3 mutation was investigated clinically and with spectral psychophysics. The post mortem retina from one of these ESCS patients who was homozygous for the R311Q mutation was studied with histopathological and immunocytochemical techniques. Results: The phenotype of patients with NR2E3 R311Q mutations included: marked rod dysfunction, an abnormally high ratio of S to L/M cone function, and retinal degeneration. Serial data over a decade proved the progressive nature of the retinopathy. In the donor retina, no rods were identified but cones were increased two-fold and 92% were S cones. Only 15% of the cones expressed L/M cone opsin and some of these co-expressed S cone opsin. The retina was disorganized with densely packed cones intermixed with inner retinal neurons. The retina was also degenerate, retaining photoreceptors in only the macula and far periphery. Conclusion: NR2E3 plays a key role in regulation of human photoreceptor development. Degeneration of the NR2E3 R311Q retina may be secondary to the developmental defect, known S cone fragility, and/or lack of normal maintenance of mature photoreceptors
Keywords: 562 retinal degenerations: hereditary • 564 retinal development • 517 photoreceptors