ASSOCIATION OF PIGMENTED PARAVENOUS RETINOCHOROIDAL ATROPHY WITH A PATHOGENIC VARIANT IN THE HK1 GENE

Pigmented paravenous retinochoroidal atrophy and retinitis pigmentosa-like phenotype in the same patient: A case series

INTRODUCTION

Concomitant manifestation of PPRCA in one eye and RP-like retinopathy in the fellow eye is a rare clinical entity, with limited published descriptions to date. The aim of this study is to describe comprehensive clinical evaluations and long-term follow-up of three patients affected by this clinical picture.

METHODS

Three patients with concurrent PPRCA and RP-like retinopathy were prospectively re-evaluated and comprehensive assessments were performed. The progression of disease was assessed by comparing best corrected visual acuity (BCVA) and ellipsoid zone (EZ) width with data available from each patient's medical charts and previous SD-OCT scans. Blood samples were collected and tested to rule out autoimmune or infectious ocular diseases, for testing anti-retinal autoantibodies (ARAs) and for genetic analysis.

RESULTS

Reduction in BCVA and a progressive concentric loss of the EZ band over time were detected in the eye with RP-like phenotype in all three patients, while in the eye with PPRCA none of the patients showed significant changes in BCVA and only one patient showed a progressive reduction of the EZ width. No clear etiology has been identified. Two or more ARAs subtypes were detected in two out of three patients.

CONCLUSIONS

PPRCA was demonstrated to be a non-progressive or slowly progressive disease, instead the eye with RP-like phenotype showed a progressive visual impairment, highlighting the importance of shedding light on this condition. Its etiology remains unclear: a genetic trait with different phenotype between the two eyes is conceivable, as well as a potential role of ARAs.

Pigmented paravenous chorioretinal atrophy: Updated scenario

Pigmented paravenous chorioretinal atrophy (PPCRA) is an uncommon form of chorioretinal atrophy characterized by perivenous aggregations of pigment clumps associated with peripapillary and radial zones of retinal pigment epithelial atrophy that are distributed along the retinal veins. Most patients are asymptomatic, and evidence suggest that PPCRA is slowly progressing. Unless macular involvement is present, the majority of patients usually retain a normal visual function. Our ability to diagnose PPCRA has recently improved thanks to multimodal imaging, especially with the advent of ultra-widefield (UWF) imaging. Blood tests and functional and genetic testing can help with the correct differential diagnosis of pseudo-PPCRA or other disorders with similar characteristics. Although the cause of PPCRA is unknown, it is possible that it has a genetic basis. In this review we provide a summary of the multimodal imaging characteristics of PPCRA, and discuss its possible pathogenesis, based on the genes that have been associated with this disease.

variant associated with pigmented paravenous chorioretinal atrophy

PURPOSE

To report a case of Pigmented Paravenous Chorioretinal Atrophy (PPCRA) associated with a novel RPGRIP1 dominant variant.

METHODS

Case report. The patient underwent multimodal retinal imaging, including spectral-domain optical coherence tomography (OCT), OCT Angiography (OCTA), blue-light autofluorescence (BAF), and ultra-widefield pseudocolor retinography and autofluorescence. Genetic testing was performed using next-generation sequencing.

RESULTS

A 67-year-old male presented with a clinical suspicion of retinitis pigmentosa. His best-corrected visual acuity was 20/32 in the right eye and 20/200 in the left eye. On fundus examination, paravenous pigment clumping and chorioretinal atrophy were seen bilaterally, matching confluent hypoautofluorescent areas departing from the optic disc. This clinical presentation suggested a case of PPCRA. Genetic testing found a heterozygous deletion of nucleotide 631 (c.631del) in the RPGRIP1 gene, a frameshift variant that generates a premature stop codon (p.Ser211Valfs*64) and therefore results in a truncated or absent protein product. The variant was regarded as likely pathogenic (class IV).

CONCLUSION

In this report, we describe a case of PPCRA in association with a novel, likely pathogenic c.631del, p.Ser211Valfs*64 variant in RPGRIP1, a gene that has been associated with Leber congenital amaurosis and cone-rod dystrophy. Our case expands the spectrum of genes associated with PPCRA and prompts further studies to ascertain the molecular etiopathogenesis of this disease.

OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FINDINGS IN PIGMENTED PARAVENOUS CHORIORETINAL ATROPHY

PURPOSE

To analyze the retino-choroidal vascular characteristics of patients affected by pigmented paravenous chorio-retinal atrophy by means of optical coherence tomography (OCT) angiography.

METHODS

This study was designed as an observational, cross-sectional case series. Multimodal imaging included fundus autofluorescence, structural OCT, and OCT angiography. The quantitative OCT angiography analyses included the calculation of the vessel density and choriocapillaris porosity.

RESULTS

Overall, 12 patients (24 eyes) affected by pigmented paravenous chorio-retinal atrophy were recruited. Structural OCT of the areas involved by pigmented paravenous chorio-retinal atrophy as visualized on the fundus autofluorescence showed a complete ellipsoid zone and external limiting membrane absence, with thinning of ganglion cell complex, outer nuclear layer, and outer plexiform layer, but associated with the optical partial preservation of the retinal pigment epithelium. Optical coherence tomography angiography quantitative assessment of the retinal regions affected by PPRCA, as visualized by fundus autofluorescence, was characterized by normal vessel density at the level of superficial capillary plexus but significantly altered vessel density of deep capillary plexus and choriocapillaris, with higher choriocapillaris porosity. The presence of macular atrophy was significantly correlated with worse deep capillary plexus and choriocapillaris vessel density values. Furthermore, a statistically significant correlation between the fundus autofluorescence patterns and the retinal vascular status was found.

CONCLUSION

Optical coherence tomography angiography quantitative analyses in pigmented paravenous chorio-retinal atrophy demonstrate a specific impairment at the level of the deep capillary plexus, which could in turn bring about a thinning of ganglion cell complex and outer nuclear layer. The alterations at the level of the choriocapillaris and the choroid, in general, could then represent a secondary effect.