Abstract
Purpose: :
Autoimmune retinopathy is a pathogenic, typically non-inflammatory immunologic process that leads to retinal degeneration due to recognition of retinal proteins as autoantigens. In this study we investigated the cause of retinal degeneration in a patient who initially appeared to have an early onset inherited retinal degeneration but was later diagnosed with autoimmune retinopathy.
Methods: :
Extensive screening of genes associated with early onset retinal degeneration was performed. Western blots of bovine and human retina were used to assay the patient’s serum for antiretinal antibodies. To identify the retinal protein that showed reactivity with the patient’s serum, 2-D electrophoresis and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry were used.
Results: :
Screening of the coding sequences of genes known to cause early onset retinal degeneration (CRB1, RDH12, GUCY2D, AIPL1, RPE65, CRX, RPGRIP1, LRAT, CEP290, RD3, TULP1) did not reveal any disease-causing mutations. The patient’s serum showed a single strong band of anti-retinal reactivity to a protein with a molecular weight of approximately 49kDa, which was later identified as γ-enolase through MALDI mass spectrometry. In contrast, obvious anti-γ-enolase activity was not observed in 5 patients with inflammatory retinal disease, 8 patients with autoimmune retinal disease, 9 patients with molecularly confirmed retinal degeneration, and 6 normal individuals. The anti-γ-enolase antibodies included antibodies from IgG, IgA, and IgM classes.
Conclusions: :
The combination of clinical and laboratory findings of this patient suggest that autoantibodies targeting γ-enolase may cause autoimmune retinopathy leading to retinal degeneration that resembles genetic forms of retinal degeneration.
Keywords: autoimmune disease • retinal degenerations: hereditary