title: GCAP1, Rab6, and HSP27: Novel Autoantibody Targets in Cancer-Associated Retinopathy and Autoimmune Retinopathy.
abstract: OBJECTIVE
  Autoantibodies (AAbs) with different retinal specificities were reported in cancer-associated retinopathy (CAR) and autoimmune retinopathy (AR). The goal was to identify the small retinal proteins of apparent molecular mass of 23-kDa often recognized by patients' AAbs.
  
  
  METHODS
  Sera specific for a 23-kDa retinal protein of 173 patients were investigated retrospectively by Western blotting and double immunofluorescence confocal microscopy. A proteomic analysis revealed new 23-kDa protein candidates, including guanylyl cyclase-activating proteins (GCAPs), heat shock protein 27 (HSP27), and Rab6A GTPase (Rab6A).
  
  
  RESULTS
  Among the cohort of 173 patients, only 68 had anti-recoverin AAbs and the remaining 105 reacted with 4 unique proteins, which were identified as a Rab6A, HSP27, GCAP1, and GCAP2. Confocal images from a double labeling study confirmed the reactivity of AAbs with different types of cells in human retina, consistent with the target protein's respective cellular functions. Patients (62/173) had been diagnosed with various kinds of cancer, including 20% of patients who had anti-recoverin, 11% anti-Rab6A, and 5% anti-HSP27 AAbs. Only 50% of recoverin-seropositive patients had cancer and the individuals with anti-recoverin AAbs had a significantly higher likelihood to be diagnosed with cancer than patients with other anti-23-kDa AAbs.
  
  
  CONCLUSIONS
  The newly discovered retinal autoantigens may be involved in pathogenicity of CAR and AR. The recognition of AAbs against various retinal proteins associated with autoimmune retinal degeneration broadens the group of proteins related with these entities.
  
  
  CONCLUSIONS
  Patients with anti-recoverin, anti-GCAP1, anti-Rab6A, and anti-HSP27 AAbs represented diverse clinical phenotypes, so the presence of disease-associated AAbs provides important information for molecular diagnosis.
authors.affiliation: Casey Eye Institute, School of Medicine, Oregon Health and Science University, Portland, OR, USA.
authors.forename: Sufang
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Research, Salus University, Elkins Park, PA, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Dizhoor
authors.affiliation: Casey Eye Institute, School of Medicine, Oregon Health and Science University, Portland, OR, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wilson
authors.affiliation: Casey Eye Institute, School of Medicine, Oregon Health and Science University, Portland, OR, USA.
authors.forename: Grazyna
authors.initials: G
authors.lastname: Adamus
keywords: cancer-associated retinopathy; autoimmune response; disease; recoverin