Retinal Histopathology in Eyes from Patients with Best Disease Caused by VMD2 Mutations

Abstract

Purpose: To compare the histopathology in donor eyes from patients with Best disease (BD) caused by p.Asn296His and p.Ile201Thr VMD2 mutations.

Methods: Eyes were obtained from 85 (donor 1, female), and 65 year-old (donor 2, male) postmortem donors, and were fixed within 25 hrs postmortem. Globes were evaluated with macroscopic, SLO and OCT imaging. Perifoveal and peripheral retinas were processed for electron microscopy and immunocytochemistry using cell-specific antibodies. Four age-similar normal eyes were used as controls. DNA was obtained from donor blood samples. Sequence analysis of the entire VMD2 coding region was performed.

Results: DNA analysis of donor 1 detected an p.Asn296His VMD2 mutation. DNA analysis of donor 2 detected an p.Ile201Thr VMD2 mutation. Fundus examination showed that donor 1 displayed a macular lesion with considerable scarring while donor 2 displayed close to normal macular morphology. Imaging modalities indicated considerable retinal atrophy in the perifoveal region of donor 1. In each BD donor, histology showed a distinct ganglion cell layer (GCL), inner nuclear layer (INL), outer nuclear layer (ONL), RPE and choriocapillaris (CC) in the periphery. In addition, donor 1 displayed edema of the interphotoreceptor matrix. Prominent GCL and INL were evident in the perifovea of donor 1. An extensive fibrovascular scar was present between Bruch’s membrane and the retina; this area displayed patchy thin RPE with no photoreceptors. In contrast, the perifoveal region of donor 2 had distinct GCL, INL, ONL and robust RPE and CC. Cells labeled with cone opsin and arrestin antibodies were evident in the macula, but mostly absent in the retina adjacent to the fibrovascular scar of donor 1. In the periphery of both BD donors, cells labeled with cone specific antibodies were present. Cells labeled with rhodopsin antibody were detected in the perifovea but not in the fibrovascular scar area of donor 1. Cells labeled with rhodopsin were present in the periphery of both donors. Autofluorescent material in the perifoveal region was significantly reduced in areas where the RPE was still present in donor 1.

Conclusions: The histopathology of the retina from an individual with VMD2 p.Asn296His mutation displayed highly degenerated perifoveal retina. The retina in the individual with p.Ile201Thr VMD2 mutation displayed normal perifoveal morphology and preservation of cones and rods in the periphery.

Keywords: 695 retinal degenerations: cell biology • 599 microscopy: light/fluorescence/immunohistochemistry • 539 genetics