Retinal Histopathology in Eyes from Patients with Autosomal Dominant Retinitis Pigmentosa caused by Rhodopsin Mutations

Abstract

Purpose: To compare the histopathology in donor eyes from patients with autosomal dominant retinitis pigmentosa caused by Pro23His, Pro347Thr and Pro347Leu rhodopsin mutations.

Methods: Eyes were obtained from 72, 80 and 83 year-old donors and fixed in 4% paraformaldehyde and 0.5% glutaraldehyde in PBS within 8 to 17.5 hours postmortem. Globes were evaluated with macroscopic, SLO and OCT imaging. Macula and peripheral regions were processed for microscopy and immunocytochemistry. Three age-matched normal eyes were used as controls. DNA was obtained from blood and buccal samples of the donor and family members. Direct genomic sequencing of the entire rhodopsin coding region and flanking intronic sequences was performed.

Results: DNA analysis of the donors and affected family members revealed rhodopsin Pro23His, Pro347Thr and Pro347Leu mutations. Histopathological findings in the retina of the donor carrying a Pro23His rhodopsin mutation were reported previously and are compared here to donors carrying the Pro347Thr and Pro347Leu mutations. The area surrounding the optic nerve showed evidence of RPE atrophy as choroidal vasculature could be visualized in the Pro23His and Pro347Thr eyes. A prominent inner nuclear layer was present in the perifoveal region in the Pro23His eye. In addition, the RPE was reduced from normal thickness in the macula in the Pro23His eye while it was discontinuous in the Pro347Thr and Pro347Leu eye in the macular region. Cones labeled with opsin and arrestin antibodies were present in the macula, but were mostly absent from the periphery in the Pro23His eye. Few cones were present in the Pro347Thr and Pro347Leu eyes. A few highly disorganized, rhodopsin labeled rods were detected in the macula but were absent in the periphery of the Pro23His eye. The retinas of the Pro347Thr and Pro347Leu eyes showed almost complete absence of rhodopsin labeled rods in both the perimacula and periphery.

Conclusions: The histopathology of the retina in patients with Pro23His rhodopsin mutation displayed highly degenerate peripheral retina and preservation of some cone and rod photoreceptors in the macula. The retina in patients with Pro347Thr and Pro347Leu rhodopsin mutations displayed near-complete loss of rods and the presence of few cones in the macula.

Keywords: 695 retinal degenerations: cell biology • 554 immunohistochemistry • 539 genetics