Retinal findings in a patient of French ancestry with CABP4-related retinal disease
CABP4-related retinal dysfunction is a cone–rod synaptic transmission disorder with electronegative electroretinogram (ERG) waveform. It is a rare retinal dysfunction that can be classified into the incomplete form of congenital stationary night blindness. Absent foveal reflex and overall foveal thinning were previously reported, but in most cases the fundus appearance was described as nearly normal. We report here peculiar macular changes in a patient of French ancestry harbouring CABP4 mutations.
Complete ocular examination and full-field ERG were performed at the initial presentation and follow-up. Multimodal fundus imagining, including spectral-domain optical coherence tomography, colour, infrared reflectance and short-wavelength autofluorescence photographs, was performed during follow-up visits.
A 7-month-old infant was addressed to our department for visual unresponsiveness and nystagmus. ERG had an electronegative waveform, even for light-adapted stimuli, thus supporting the diagnosis of photoreceptor–bipolar cell transmission disorder. Genetic investigations discovered a compound heterozygous mutation in CABP4: c.646C > T, p.Arg216*/c.673C > T, p.Arg225*. Multimodal fundus imaging, performed at follow-up visits, showed fine radial folds at the vitreomacular interface and dark foveal dots in both eyes. Optic coherence tomography revealed a focal foveal ellipsoid zone gap.
Initial presentation was misleading with Leber congenital amaurosis. The electronegative ERG waveform reoriented the genetic investigations and thus establishing a correct diagnosis. To the best of our knowledge, the peculiar fundus changes observed in our patient were never reported before. We hypothesized that a foveal ellipsoid zone interruption discovered in our patient could reflect mostly a cone dysfunction. It was unclear whether the fine radial folds in both maculae were linked with high hyperopia or were an intrinsic feature of the retinal disease.
CABP4-related retinal disease is a cone–rod system disorder with possible foveal abnormalities.
KeywordsCABP4 Electroretinography Hemeralopia OCT Multimodal fundus imaging
We thank the family for participating in the study. We are grateful to Mr. Philippe Debruyne, Engineer in Exploration of Visual Function and Neuro-Ophthalmology Department, who kindly helped us for the illustration. We also thank Aline Antonio for DNA extraction and Christel Condroyer for Sanger sequencing validation.
Compliance with ethical standards
Conflict of interest
Statement of human rights
This retrospective study was approved by our Institutional Review Board and fulfilled the tenets of the Declaration of Helsinki.
Statement on the welfare of animals
No animals participed in this study.
Informed consent was obtained for all participants to the study.
Patients’ parents have consented to the submission of the case report to the journal.
Indian Council of Medical Research and INSERM (France), an Indo-French collaborative program (No: 53/1/Indo-Foreign/Oph/10-NCD-II).
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