Retinal Histopathology from a Patient with Autosomal Recessive Retinitis Pigmentosa caused by EYS Mutations

Abstract

Purpose: : To evaluate the histopathology in donor eyes from a patient with autosomal recessive retinitis pigmentosa (arRP) caused by EYS mutations.

Methods: : Eyes were obtained from a 72 year-old female who died from pancreatic cancer. Eyes were fixed in 4% paraformaldehyde and 0.5% glutaraldehyde in PBS within 6 hours postmortem. Globes were evaluated with macroscopic, SLO and OCT imaging. Macula and peripheral regions were processed for electron microscopy and immunocytochemistry. An age-matched normal eye and the eye donated by the donor’s asymptomatic mother were used as controls. DNA was obtained from blood samples of the donor, her affected brother and sister, and two unaffected sisters. Direct genomic sequencing of 19 arRP genes was performed.

Results: : DNA analysis of the affected brother revealed the novel EYS gene mutations, IVS11+1G>A and Q874X. Imaging revealed peripheral bone spicules and RPE atrophy immediately surrounding the optic nerve and macula. SLO showed demarcated, circular patches of hypofluorescence in the perimacula region of both eyes, suggesting focal loss of RPE as choroidal vasculature could be visualized. Histology revealed a highly degenerate retina with little evidence of stratified nuclear layers in all peripheral areas studied. In contrast, the macula and perimacula region contained well organized ganglion cell and inner nuclear layer with only a few nuclei remaining in the outer nuclear layer. The RPE was thin in the macula and absent in the far periphery. An amorphous material was present between the degenerate retina and the RPE in the macula. Rhodopsin labeled rods were absent except in the far periphery. Cones labeled with opsin and arrestin antibodies were present in the macula, but were mostly absent from the periphery. Cone synapses and outer segments were not observed. Calbindin labeled second order neurons were unevenly distributed in the periphery.

Conclusions: : Advanced retinal degenerative changes with near-total absence of rods and preservation of macular cones characterize the retinal histopathology of an arRP patient due to EYS mutations.

Keywords: retinal degenerations: cell biology • immunohistochemistry • genetics