Juvenile X-linked retinoschisis with normal scotopic b-wave in the electroretinogram at an early stage of the disease.
OBJECTIVE
To report four cases of genetically verified juvenile X-linked retinoschisis (XLRS) with normal scotopic b-waves in full-field ERG, including one patient with a novel mutation (W50X) in the RS1 gene.


METHODS
Four XLRS patients from different families were examined with regard to visual acuity, kinetic perimetry, fundus photography, full-field ERG, and OCT. Two of these patients were also examined with multifocal-ERG (mfERG). Mutations in the RS1 gene were identified by sequence analysis.


RESULTS
The full-field ERG presented normal b-wave amplitudes on scotopic white-light stimulation. OCT and mfERG presented macular schisis and macular dysfunction. Genetic analysis revealed a deletion of exon 1 and the promotor region in one patient and mutations giving rise to the amino acid substitutions R209C and W96R in two others. The fourth patient carried a novel mutation in exon 3 of the RS1 gene (nt 149 G-->A), causing the introduction of a stop codon after amino acid 49 in the RS protein.


CONCLUSIONS
Four young males with XLRS did not present with reduction in the scotopic b-wave amplitude on full-field ERG, which is otherwise often considered to be characteristic of the disease. Full-field ERG and molecular genetic analysis of the RS1 gene still remain the most important diagnostic tools for this retinal disorder, although the OCT can be a valuable complement in order to make the diagnosis at an early stage.
Eksandh
Louise
L
Department of Ophthalmology, University Hospital of Lund, Sweden. louise.eksandh@telia.com
Andréasson
Sten
S
Abrahamson
Magnus
M
D002648:Child; D004252:DNA Mutational Analysis; D003623:Dark Adaptation; D004596:Electroretinography; D005091:Exons / Q000235:genetics; D005136:Eye Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D009154:Mutation; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D041441:Retinoschisis / Q000235:genetics / Q000503:physiopathology*; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D058609:Visual Field Tests
D005136:Eye Proteins; C108726:RS1 protein, human