Purpose:
To ascertain cross-sectional morphological data in Abyssinian cats from a pedigree segregating for autosomal recessive late-onset photoreceptor degeneration caused by a mutation in the CEP290 gene.
Methods:
In vivo imaging with confocal scanning-laser ophthalmoscopy (cSLO) and optical coherence tomography (SpectralisTM OCT) was performed in seven cats, aged between 1 and 11 years, and classified ophthalmoscopically as rdAC stages 1 to 4. Genomic DNA was sequenced in affected and unaffected individuals of exon 50/ intron 50 junction to confirm the mutation.
Results:
The morphological assessment performed allowed to identify changes associated with the retinal and choroidal vasculature (SLO angiography), the thickness of the retina (OCT) and respective topographical differences, as well as the correlation of the in vivo morphology with published histological data, including the identification of the tapetum. The different stages were well distinguishable by OCT thickness data, particularly revealing the outer retina as the layer to be affected first. Similar to the concentric topography in RP, the degeneration in rdAc affected the visual streak and the area centralis less and/or later than the other regions.
Conclusions:
The rdAc cat, featuring a splicing defect in the CEP290 gene resulting in the introduction of a premature stop codon, is one of the few large animal models for human RP; CEP290 mutations have so far been described specifically in Joubert syndrome and a form of LCA. Here, we provide for the first time an extensive in vivo evaluation of the retinal morphology at different disease stages. The findings may help to better understand the pathophysiological disease processes and constitute a basis for future treatment trials on the way to the translation of therapeutic strategies to human patients.
Keywords: imaging/image analysis: non-clinical • degenerations/dystrophies • retina: distal (photoreceptors, horizontal cells, bipolar cells)