Central areolar choroidal dystrophy associated with dominantly inherited drusen

Retinal Dystrophies Associated With Peripherin-2: Genetic Spectrum and Novel Clinical Observations in 241 Patients

Purpose

To describe the clinical, electrophysiological and genetic spectrum of inherited retinal diseases associated with variants in the PRPH2 gene.

Methods

A total of 241 patients from 168 families across 15 sites in 9 countries with pathogenic or likely pathogenic variants in PRPH2 were included. Records were reviewed for age at symptom onset, visual acuity, full-field ERG, fundus colour photography, fundus autofluorescence (FAF), and SD-OCT. Images were graded into six phenotypes. Statistical analyses were performed to determine genotype-phenotype correlations.

Results

The median age at symptom onset was 40 years (range, 4-78 years). FAF phenotypes included normal (5%), butterfly pattern dystrophy, or vitelliform macular dystrophy (11%), central areolar choroidal dystrophy (28%), pseudo-Stargardt pattern dystrophy (41%), and retinitis pigmentosa (25%). Symptom onset was earlier in retinitis pigmentosa as compared with pseudo-Stargardt pattern dystrophy (34 vs 44 years; P = 0.004). The median visual acuity was 0.18 logMAR (interquartile range, 0-0.54 logMAR) and 0.18 logMAR (interquartile range 0-0.42 logMAR) in the right and left eyes, respectively. ERG showed a significantly reduced amplitude across all components (P < 0.001) and a peak time delay in the light-adapted 30-Hz flicker and single-flash b-wave (P < 0.001). Twenty-two variants were novel. The central areolar choroidal dystrophy phenotype was associated with 13 missense variants. The remaining variants showed marked phenotypic variability.

Conclusions

We described six distinct FAF phenotypes associated with variants in the PRPH2 gene. One FAF phenotype may have multiple ERG phenotypes, demonstrating a discordance between structure and function. Given the vast spectrum of PRPH2 disease our findings are useful for future clinical trials.

MULTIMODAL RETINAL IMAGING REVEALS NEW PATHOGENIC INSIGHTS IN CENTRAL AREOLAR CHOROIDAL DYSTROPHY: A CASE SERIES

PURPOSE

To describe novel imaging findings in a family affected by central areolar choroidal dystrophy.

METHODS

Case series with multimodal retinal imaging assessment.

RESULTS

A 19-year-old asymptomatic woman was referred for bilateral macular defects of the retinal pigment epithelium. Blue-light autofluorescence of her right eye revealed a speckled pattern in the macular area with a ring of decreased autofluorescence using near-infrared autofluorescence. Multimodal assessment of her left eye disclosed a single parafoveal spot of decreased pigmentation that was clearly visible as hyperautofluorescent using blue-light autofluorescence and as hypoautofluorescent using near-infrared autofluorescence. Optical coherence tomography angiography revealed several tiny areas of flow voids in correspondence of the retinal pigment epithelium alterations of both eyes. Three family members were recently diagnosed with presumed age-related macular degeneration and demonstrated well-demarcated areas of retinal pigment epithelium atrophy surrounded by yellowish deposits and a hypopigmented halo. Next-generation genetic analysis for inherited macular dystrophies was performed on the index case and the affected family members and revealed a p.Arg172Gln missense mutation in PRPH2 gene, leading to the diagnosis of central areolar choroidal dystrophy.

CONCLUSION

Multimodal imaging can reveal new pathogenic insights in central areolar choroidal dystrophy. Of notice, near-infrared autofluorescence and optical coherence tomography angiography are able to detect retinal pigment epithelium hypopigmentation and choriocapillaris rarefaction, respectively, since the earliest stages of the disease.

New Insights on the Regulatory Gene Network Disturbed in Central Areolar Choroidal Dystrophy-Beyond Classical Gene Candidates

Central areolar choroidal dystrophy (CACD) is a rare hereditary disease that mainly affects the macula, resulting in progressive and usually profound visual loss. Being part of congenital retinal dystrophies, it may have an autosomal dominant or recessive inheritance and, until now, has no effective treatment. Given the shortage of genotypic information about the disease, this work systematically reviews the literature for CACD-causing genes. Three independent researchers selected 33 articles after carefully searching and filtering the Scielo, Pubmed, Lilacs, Web of Science, Scopus, and Embase databases. Mutations of six genes (PRPH2, GUCA1A, GUCY2D, CDHR1, ABCA4, and TTLL5) are implicated in the monogenic dominant inheritance of CACD. They are functionally related to photoreceptors (either in the phototransduction process, as in the case of GUCY2D, or the recovery of retinal photodegradation in photoreceptors for GUCA1A, or the formation and maintenance of specific structures within photoreceptors for PRPH2). The identified genetic variants do not explain all observed clinical features, calling for further whole-genome and functional studies for this disease. A network analysis with the CACD-related genes identified in the systematic review resulted in the identification of another 20 genes that may influence CACD onset and symptoms. Furthermore, an enrichment analysis allowed the identification of 13 transcription factors and 4 long noncoding RNAs interacting with the products of the previously mentioned genes. If mutated or dysregulated, they may be directly involved in CACD development and related disorders. More than half of the genes identified by bioinformatic tools do not appear in commercial gene panels, calling for more studies about their role in the maintenance of the retina and phototransduction process, as well as for a timely update of these gene panels.

Evaluating the Occurrence of Rare Variants in the Complement Factor H Gene in Patients With Early-Onset Drusen Maculopathy

Question

What are the genotypic and phenotypic characteristics of patients with early-onset drusen maculopathy?

Findings

In this case-control study, patients with early-onset drusen maculopathy were frequently carriers of rare genetic variants in the complement factor H gene and were characterized by the presence of a large macular drusen area and lower genetic risk scores compared with patients with age-related macular degeneration.

Meaning

Sequencing of the complement factor H gene is important in considering future treatments targeting the complement system in patients with early-onset drusen maculopathy. Furthermore, the presence of a large macular drusen area supports the severe phenotype in these patients, who may be at high risk of developing geographic atrophy or choroidal neovascularization.

Importance

Early-onset drusen maculopathy (EODM) is a severe disease and can lead to advanced macular degeneration early in life; however, genetic and phenotypic characteristics of individuals with EODM are not well studied.

Objective

To identify genotypic and phenotypic characteristics of individuals with EODM.

Design, Setting, and Participants

This case-control study collected data from the European Genetic Database from September 2004 to October 2019. A total of 89 patients with EODM diagnosed at 55 years or younger and 91 patients with age-related macular degeneration (AMD) diagnosed at 65 years or older were included.

Exposures

Coding regions of CFH, CFI, C3, C9, CFB, ABCA4, PRPH2, TIMP3, and CTNNA1 genes were sequenced, genetic risk scores (GRS) were calculated based on 52 AMD-associated variants, and phenotypic characteristics on color fundus photographs were analyzed comparing patients with EODM and AMD.

Main Outcomes and Measures

GRS, frequency of rare genetic complement variants, and phenotypic characteristics.

Results

This case-control study included 89 patients with EODM (mean [SD] age, 51.8 [8.7] years; 58 [65.2%] were female) and 91 patients with AMD (mean [SD] age, 77.6 [6.1] years; 45 [49.5%] female). At a mean (SD) age of 56.4 (7.3) years, 40 of 89 patients with EODM (44.9%) were affected by geographic atrophy or choroidal neovascularization. A lower GRS was observed in patients with EODM compared with patients with AMD (1.03 vs 1.60; P = .002), and 27 of 89 patients with EODM (30.3%) carried rare variants in the CFH gene compared with 7 of 91 patients with AMD (7.7%). Carriership of a rare CFH variant was associated with EODM (odds ratio, 7.2; 95% CI, 2.7-19.6; P < .001). A large macular drusen area (more than 50% covered with drusen) was observed in patients with EODM (24 of 162 eyes [14.8%]) compared with patients with AMD (9 of 164 eyes [5.5%]) (odds ratio, 4.57; 95% CI, 1.5-14.1; P = .008).

Conclusions and Relevance

A large proportion of patients with EODM in this study carried rare CFH variants, with most of the identified CFH variants clustered in the first 7 complement control protein domains affecting factor H and factor H–like 1. Because EODM frequently leads to advanced macular degeneration at an early age and can result in many years of vision loss, this study supports targeting the complement system and sequencing the CFH gene in patients with EODM to improve genetic counseling and future treatments for AMD.

PRPH2 mutation update: In silico assessment of 245 reported and 7 novel variants in patients with retinal disease

Mutations in PRPH2, encoding peripherin-2, are associated with the development of a wide variety of inherited retinal diseases (IRDs). To determine the causality of the many PRPH2 variants that have been discovered over the last decades, we surveyed all published PRPH2 variants up to July 2020, describing 720 index patients that in total carried 245 unique variants. In addition, we identified seven novel PRPH2 variants in eight additional index patients. The pathogenicity of all variants was determined using the ACMG guidelines. With this, 107 variants were classified as pathogenic, 92 as likely pathogenic, one as benign, and two as likely benign. The remaining 50 variants were classified as variants of uncertain significance. Interestingly, of the total 252 PRPH2 variants, more than half (n = 137) were missense variants. All variants were uploaded into the Leiden Open source Variation and ClinVar databases. Our study underscores the need for experimental assays for variants of unknown significance to improve pathogenicity classification, which would allow us to better understand genotype-phenotype correlations, and in the long-term, hopefully also support the development of therapeutic strategies for patients with PRPH2-associated IRD.

Genetic screening for macular dystrophies in patients clinically diagnosed with dry age-related macular degeneration

It can be clinically challenging to distinguish dry age‐related macular degeneration (AMD) from AMD‐mimicking dystrophies, and sometimes misdiagnosis occurs. With upcoming therapies for dry AMD it is important to exclude patients with a different retinal disease from clinical trials. In this study we evaluated the occurrence of AMD‐mimicking dystrophies in an AMD cohort. Whole‐exome sequencing (WES) was performed in 218 patients with intermediate AMD or geographic atrophy secondary to AMD and 133 control individuals. WES data was analyzed for rare variants in 19 genes associated with autosomal dominant and recessive macular dystrophies mimicking AMD. In three (1.4%) of 218 cases we identified a pathogenic heterozygous variant (PRPH2 c.424C > T; p.R142W) causal for autosomal dominant central areolar choroidal dystrophy (CACD). Phenotypically, these patients all presented with geographic atrophy. In 12 (5.5%) of 218 cases we identified a heterozygous variant of unknown clinical significance, but predicted to be highly deleterious, in genes previously associated with autosomal dominant macular dystrophies. The distinction between AMD and AMD‐mimicking dystrophies, such as CACD, can be challenging based on fundus examination alone. Genetic screening for genes associated with macular dystrophies, especially PRPH2, can be beneficial to help identify AMD‐mimicking dystrophies.

A long history of dense deposit disease

BACKGROUND

Dense Deposit Disease is a rare condition affecting the Bruch's membrane and the glomerular basement membrane. We report the progression of the ocular manifestations over a 30 year follow up period, longer than any previous report.

CASE PRESENTATION

A 44 year old male presented with pigmentary changes at the macula noted by his optician. Best corrected visual acuity at presentation was good in both eyes. Fundoscopy showed pigmentary changes and drusen, and investigation using intravenous fundus fluorescein angiography did not demonstrate any choroidal neovascular membrane. The patient subsequently developed renal failure and received a dual renal transplant. The transplanted kidneys also failed over the coming year. The patient's vision gradually deteriorated and comparison between the images in 2010 and 1985 demonstrated a clear progression of the macula changes. Optical coherence tomography showed multiple subretinal hyper reflective drusenoid deposits. These deposits were also noted to be autofluorescent on blue auto-fluorescence. The young age at presentation of drusen, combined with the history of recurrent kidney failure and progression of subretinal deposits led to a diagnosis of dense deposit disease.

CONCLUSIONS

Dense deposit disease is a rare condition affecting Bruch's membrane, but should be considered in the differential diagnosis of any patient under the age of 50 years presenting with drusen.

Multimodal Imaging for Differential Diagnosis of Bietti Crystalline Dystrophy

PURPOSE

To evaluate the diagnostic usefulness of multimodal imaging in patients with Bietti crystalline dystrophy (BCD).

DESIGN

Retrospective cross-sectional study.

PARTICIPANTS

Patients with chorioretinal dystrophy accompanied by crystalline-like deposits. The right eyes of the patients were analyzed.

METHODS

Fundus photograph, near-infrared reflectance (NIR), fundus autofluorescence (FAF), and OCT images were evaluated. Presence of hyperreflectivity on NIR, well-demarcated areas of decreased FAF, hyperreflective material at or on the retinal pigment epithelium-Bruch's membrane complex, and outer retinal tubulation were graded for each patient. All exons and franking introns of CYP4V2 were screened using Sanger sequencing.

MAIN OUTCOME MEASURES

Sensitivity and specificity of the findings to discriminate patients with and without CYP4V2 mutation.

RESULTS

In total, 33 patients were included in the study. Sanger sequencing revealed homozygous or compound heterozygous CYP4V2 mutations in 20 patients and heterozygous mutations in 2 patients. Among the investigated factors, hyperreflective appearance on NIR imaging yielded 100% sensitivity and 100% specificity in this cohort. The presence of outer retinal tubulation also was sensitive (95%), but specificity was moderate (45%). The revised diagnoses of patients without CYP4V2 mutations included retinitis pigmentosa, late-onset macular dystrophy, and central areolar choroidal dystrophy.

CONCLUSIONS

Multimodal imaging, especially NIR imaging, is useful to differentiate BCD patients with CYP4V2 mutations from patients with other chorioretinal dystrophies accompanied by crystalline-like retinal deposits.

Genetic testing for central areolar choroidal dystrophy

We studied the scientific literature and disease guidelines in order to summarize the clinical utility of the genetic test for central areolar choroidal dystrophy (CACD). CACD is mostly inherited in an autosomal dominant manner. Transmission is rarely autosomal recessive. Overall prevalence is currently 1-9 per 100 000. CACD is caused by mutations in the PRPH2 and GUCY2D genes. Clinical diagnosis is based on clinical findings, ophthalmological examination, fluorescein angiography, electroretinography (showing cone dystrophy) and stereo fundus photography. The genetic test is useful for confirming diagnosis, and for differential diagnosis, couple risk assessment and access to clinical trials.

Extensive macular atrophy with pseudodrusen-like appearance: a new clinical entity

PURPOSE

To describe a previously unreported clinical entity of progressive extensive macular atrophy and pseudodrusen-like appearance in middle-aged patients.

DESIGN

Clinical, electrophysiologic, and molecular retrospective study.

METHODS

The database of an outpatient clinic unit for genetic sensory diseases was screened for patients older than 40 years with uncharacterized macular dystrophy. Patients with extensive macular atrophy and pseudodrusen-like appearance were included.

RESULTS

Eighteen patients of 45 records (40%) matched the inclusion criteria. Bilateral polycyclic well-delineated chorioretinal atrophy extending to the temporal vascular arcades, with a larger vertical axis and without sparing of the fovea featured the macular lesion. The pseudodrusen-like appearance was widespread throughout the posterior pole and the peripheral retina. In the extreme periphery, paving stone lesions were located mostly in the inferior quadrants. In contrast to age-related macular degeneration, a rapid progression of the atrophy was observed with an early involvement of the foveal zone, thus leading to a severe visual loss. All the patients except 2 were legally blind at the end of the follow-up. Unlike age-related macular degeneration, in none of these patients did choroidal neovascularization develop. In all patients, the scotopic and photopic electroretinography responses were reduced.

CONCLUSIONS

Extensive macular atrophy with pseudodrusen should be considered as a possible pattern of severe macular dystrophy occurring in the middle-aged adult.

Phenotypic variability and long-term follow-up of patients with known and novel PRPH2/RDS gene mutations

PURPOSE

To describe the phenotypic variability in 22 patients with PRPH2 gene mutations and to report six novel mutations.

DESIGN

Retrospective study.

METHODS

Clinical examinations included color vision testing, perimetry, fundus autofluorescence (FAF), fluorescein angiography, optical coherence tomography (OCT), and full-field and multifocal electroretinography (International Society for Clinical Electrophysiology of Vision standards). Blood samples were taken for deoxyribonucleic acid (DNA) extraction and mutation screening was performed by direct sequencing of polymerase chain reaction amplicons.

RESULTS

Eleven unrelated patients and four unrelated families each with two affected members as well as one family with three affected members were examined. Diagnoses included central areolar choroidal dystrophy (CACD; n = 9), autosomal dominant retinitis pigmentosa (adRP; n = 7), adult vitelliform macular dystrophy (n = 3), and cone-rod dystrophy (CRD; n = 3). FAF was abnormal in all patients and showed various retinal pigment epithelial alterations, in CACD with a speckled FAF pattern. OCT revealed reduced retinal thickness, mostly in CACD, subretinal lesions, macula edema, or was normal. Follow-up (n = 12; range, 1.3 to 26 years) showed a slow progression of the retinal dystrophies. DNA testing revealed previously reported PRPH2 mutations in two families and eight individuals of whom two carried the same mutation but had different phenotypes. Novel PRPH2 mutations were detected in two families with adRP, in identical twins with CACD, and in each of an individual with CACD, CRD, and adRP.

CONCLUSIONS

This series describes the broad spectrum of phenotypes associated with PRPH2 mutations. FAF and OCT are helpful tools for diagnosis and evaluation of disease progression. We report novel PRPH2 mutations in patients with CACD, CRD, and adRP.

Indocyanine green angiography features of central areolar choroidal dystrophy

PURPOSE

Central areolar choroidal dystrophy is an inherited autosomal dominant macular disease characterized by a central atrophy of the retinal pigment epithelium and choriocapillaris. Our purpose was to describe fluorescein angiography and confocal indocyanine green angiography features of central areolar choroidal dystrophy.

METHODS

We performed a complete ophthalmologic examination including best corrected visual acuity, fundus examination, color fundus photographs, red free frames, fluorescein angiography, infrared, confocal indocyanine green, and electroretinography in a cohort of patients with a family history of central areolar choroidal dystrophy.

RESULTS

Eleven patients (22 eyes) affected were prospectively included. Indocyanine green differentiated two distinct phenotypes. In 9/11 patients, atrophy area was hyperfluorescent or normofluorescent. In the two other patients, the lesion was hypofluorescent from early to late phases and pinpoints were observed on the late phases.

CONCLUSION

In our small series, indocyanine green angiography distinguished two phenotypes of central areolar choroidal dystrophy, correlated with fluorescein angiography features.

The spectrum of retinal dystrophies caused by mutations in the peripherin/RDS gene

Peripherin/rds is an integral membrane glycoprotein, mainly located in the rod and cone outer segments. The relevance of this protein to photoreceptor outer segment morphology was first demonstrated in retinal degeneration slow (rds) mice. Thus far, over 90 human peripherin/RDS gene mutations have been identified. These mutations have been associated with a variety of retinal dystrophies, in which there is a remarkable inter- and intrafamilial variation of the retinal phenotype. In this paper, we discuss the characteristics of the peripherin/RDS gene and its protein product. An overview is presented of the broad spectrum of clinical phenotypes caused by human peripherin/RDS gene mutations, ranging from various macular dystrophies to widespread forms of retinal dystrophy such as retinitis pigmentosa. Finally, we review the proposed genotype-phenotype correlation and the pathophysiologic mechanisms underlying this group of retinal dystrophies.