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Gavin Arno, Panagiotis Sergouniotis, Arundhati Dev Borman, Aman Chandra, Graham Holder, Anthony Robson, Andrew Webster, Anthony Moore; Phenotypic variability in paediatric cases of enhanced S-cone syndrome (ESCS). Invest. Ophthalmol. Vis. Sci. 2013;54(15):1319.
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ESCS is consequent upon mutation in NR2E3 and is usually characterised by absence of rod photoreceptors and a retina in which the majority of cones are short-wavelength sensitive. It is one of the few disorders in which the electroretinogram (ERG) can be pathognomonic. The aim of this study was to examine the phenotypic features of ESCS in children.
Twelve children from 8 families with ECSC were ascertained. Most underwent fundus examination, ERG, fundus autofluorescence imaging (FAF) and OCT. Mutations in NR2E3 were investigated in 7 patients from 6 families where DNA was available by bidirectional sequencing of all exons and intron/exon boundaries.
All had nyctalopia from early childhood. Hypermetropia was documented in 6 cases, and 5 children from 3 families had a convergent strabismus. Median visual acuity was 0.17 logMAR. Funduscopic abnormalities along the vascular arcades were observed in 11 of 12 cases, the remaining case had a normal fundus. ERG revealed typical features associated with ECSC in 11 of 12 cases including the patient with a normal fundus. One patient had typical cone-mediated ERG abnormalities but with only mildly abnormal rod responses. Fundus autofluorescence imaging revealed high density foci along the arcades in 7 of 8 cases. Spectralis OCT assessment confirmed macular schisis-like changes in 3 of 7 cases. Mutations in NR2E3 were identified in 6 individuals from 5 families available for DNA analysis. These comprised compound heterozygous changes: c.119-2A>C and c.1194delT identified in two affected family members; c.305C>A and c.767C>A; c.119-2A>C and c.1025T>C and homozygous changes: c.1101-1G>A and c.310C>T. The novel c.1194delT (p.P399Qfs78*) mutation is predicted to cause a frameshift abolishing the correct termination codon.
This study further characterises the clinical phenotype of ESCS in children. The recognition of this phenotype allows targeted molecular screening and molecular diagnosis.
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