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Suzanne Yzer, Stephen H. Tsang, Irene A. Barbazetto, Rando Allikmets, Lawrence A. Yannuzzi; The Expanded Clinical Spectrum of Enhanced S-cone Syndrome. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6435.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the expanded clinical spectrum of enhanced S-cone syndrome (ESCS) caused by mutations in the NR2E3 gene. Nr2e3 is critical for photoreceptor differentiation and function. Mutations in NR2E3 result in an excessive production of blue opsin expressing cone cells and finally in a progressive retinal degeneration like ESCS. ESCS is typically characterized by night blindness, decreased best-corrected visual acuity (BCVA) and the presence of funduscopic changes like macular retinoschisis and a nummular type of pigmentation.
In an observational study we identified new phenotypical characteristics in a patient with ESCS (Patient 1). Upon identification of these signs we re-evaluated established ESCS syndrome patients and observed similar findings in two additional patients (Patient 2 and 3). All patients underwent a complete eye-exam including BCVA, slitlamp examination, dilated funduscopy, color fundus photography, fundus autofluorescence images, spectral domain optical coherence tomography (SD-OCT) and full-field electroretinography. The coding sequence of the NR2E3 gene was bidirectionally sequenced in all three patients.
New observations in ESCS were torpedo-like lesions which were predominantly present along the superior arcade (Patient 1, 2 and 3). These torpeda-like lesions appear to be choroidal-retinal lesions. There were bilateral large subretinal circumferential fibrotic scars in the posterior pole with a preserved fovea in patient 1. Constant findings in ESCS patients e.g. normal optic discs with relatively normal vasculature, subretinal nummular kind of pigmentary disturbances and a normal appearing far periphery were also present in our patients. FAF demonstrated a subtle ring of hyperautofluorescence between a central area of relatively spared autofluorescence and absent autofluorescence (Patient 2 and 3). FAF was also absent in areas of hyperpigmentation and fibrosis (Patient 1, 2 and 3). SD-OCT showed preserved photoreceptors in the fovea with subretinal fibrosis and outer retinal tubulation in patients 1 and 2. Signs of cystoid maculopathy were absent in all cases. All subjects exhibited typical ERG findings to support the diagnosies of ESCS. Mutation analysis of NR2E3 revealed Patient 1 and 3 to be homozygous for the c.932G>A (R311Q) mutation. Patient 2 was compound heterozygous for c.932G>A (R311Q) and c.1049A>G (Q350R).
The clinical spectrum of ESCS can be expanded with circumferential subretinal fibrosis in the macula with sparing off the fovea and torpedo-like lesions along the vascular arcades in the presence of normal optic discs and normal vasculature.
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