Distinct Phenotypic Consequences of Pathogenic Mutants Associated with Late-Onset Retinal Degeneration

An incipient late-onset retinal degeneration with a C1QTNF5 mutation: a case report with an 11-year follow-up

PURPOSE

The purpose of this study was to describe and diagnose the difficulty in a long-term follow-up (eleven years) patient with a very early presentation of late-onset retinal degeneration (L-ORD) and the significance of electrophysiological examinations and follow-up in assessing undiagnosed inherited retinal diseases.

METHODS

This is an observational case report of a 56-year-old woman, with scattered multiple yellow-white retinal dots firstly diagnosed as fundus albipunctatus. Ten years after presentation, a deterioration in rod and cone responses in ff-ERG was detected, which allowed us to discard the first diagnostic hypothesis and proceed with a genetic testing.

RESULTS

Ten years after presentation, she presented a clear progression of the abnormal photoreceptor response with a cone and rod involvement in ff-ERG, which was not compatible with the previous suspicion of fundus albipunctatus. Six months later, genetic testing results together with the typical progression of atrophic patchy lesions in multimodal imaging allowed a certain diagnosis of L-ORD, caused by an already reported pathogenic variant in the C1QTNF5 gene (c.563C > T; p. Pro188 Leu).

CONCLUSIONS

We demonstrate the importance of the ff-ERG examination and the follow-up (or ERG and imaging repetition) in the differential diagnosis of an incipient L-ORD, which can be easily misdiagnosed in the early stages, before the appearance of the characteristic chorioretinal atrophy seen with the progression of this rare disease.

Macular neovascularization in inherited retinal diseases: A review

Inherited retinal diseases (IRDs) are the most common cause of blindness in working-age adults. Macular neovascularization (MNV) may be a presenting feature or occurs as a late-stage complication in several IRDs. We performed an extensive literature review on MNV associated with IRDs. MNV is a well-known complication of Sorsby fundus dystrophy and pseudoxanthoma elasticum. Those with late-onset Stargardt disease may masquerade as exudative age-related macular degeneration (AMD) when MNV is the presenting feature. Peripherinopathies may develop MNV that responds well to a short course of anti-vascular endothelial growth factor (anti-VEGF) therapy, while bestrophinopathies tend to develop MNV in the early stages of the disease without vision loss. Enhanced S-cone syndrome manifests type 3 MNV that typically regresses into a subfoveal fibrotic nodule. MNV is only a rare complication in choroideraemia and rod-cone dystrophies. Most IRD-related MNVs exhibit a favorable visual prognosis requiring less intensive regimens of anti-vascular endothelial growth factor therapy compared to age-related macular degeneration. We discuss the role of key imaging modalities in the diagnosis of MNV across a wide spectrum of IRDs and highlight the gaps in our knowledge with respect to the natural history and prognosis to pave the way for future directions of research.