Our goal was to design a customized microarray, arrEYE, for high-resolution copy number variant (CNV) analysis of known and candidate genes for inherited retinal dystrophy (iRD) and retina-expressed ...noncoding RNAs (ncRNAs).
arrEYE contains probes for the full genomic region of 106 known iRD genes, including those implicated in retinitis pigmentosa (RP) (the most frequent iRD), cone–rod dystrophies, macular dystrophies, and an additional 60 candidate iRD genes and 196 ncRNAs. Eight CNVs in iRD genes identified by other techniques were used as positive controls. The test cohort consisted of 57 patients with autosomal dominant, X-linked, or simplex RP.
In an RP patient, a novel heterozygous deletion of exons 7 and 8 of the HGSNAT gene was identified: c.634-408_820+338delinsAGAATATG, p.(Glu212Glyfs*2). A known variant was found on the second allele: c.1843G>A, p.(Ala615Thr). Furthermore, we expanded the allelic spectrum of USH2A and RCBTB1 with novel CNVs.
The arrEYE platform revealed subtle single-exon to larger CNVs in iRD genes that could be characterized at the nucleotide level, facilitated by the high resolution of the platform. We report the first CNV in HGSNAT that, combined with another mutation, leads to RP, further supporting its recently identified role in nonsyndromic iRD.
Genet Med19 4, 457–466.
Background.
New pathogenetic treatment options, such as gene therapy, are now used to treat previously uncurable diseases. However, price of such treatment is high, especially in the case of orphan ...diseases, where costs may many-fold exceed the prices for other types of medication. This raises a question of optimal way of financing gene therapy in Russia.
Objective:
to evaluate economic consequences of centralizing procurement of gene therapy in 2021–2030 in the case of the drug indicated for treatment of biallelic RPE65 mutation-associated retinal dystrophy.
Material and methods.
Voretigene neparvovec is a new gene therapy that is used to treat RPE65 mutation-associated Leber congenital amaurosis and isolated retinitis pigmentosa. We estimated the number of patients (children and adults) that could be treated with voretigene neparvovec in 2021–2030 in Russia using demographic forecasting method, literature and expert data. Budget costs of treatment were estimated for two scenarios: status-quo, where gene therapy is purchased by regions for higher price, and centralized scenario with federal procurements and lower price for the drug.
Results.
Up to 100 children and 56 adults could be treated with voretigene neparvovec in 2021–2030 in Russia. Centralizing procurements at the expense of federal budget may save up to 20.7% or 1.8 billion rub. (1.13 billion rub. for children and 0.67 billion rub. for adults), compared to regional procurements.
Conclusion.
Centralizing procurements of expensive drugs intended for gene therapy of orphan diseases may save budget costs of the Russian Federation, compared to status-quo decentralized purchases.
Purpose
To evaluate macular vascular abnormalities in patients with macular dystrophies (MD) and retinitis pigmentosa (RP) through application of optical coherence tomography angiography (OCT-A).
...Methods
In this retrospective study, patients with MD and RP were examined by OCT-A and compared to healthy individuals. OCT-A images were analyzed regarding the diameter and surface area of the foveal avascular zone (FAZ) as well as flow (FL) in different retinal layers (superficial vascular complex (SVC), intermediate capillary complex (ICP), deep capillary complex (DCP), choriocapillaris (CC), and choroid (CD)).
Results
Twenty-one patients with MD, 21 patients with RP without macular edema (RPnE), 8 patients with RP with edema (RPwE), and 41 healthy individuals were enrolled. The group of MD and RPnE patients showed none or only minor changes in FAZ. In RPwE patients, the FAZ was significantly smaller in vertical and horizontal measurements and surface area in SVC, whereas it was markedly enlarged in ICP. FL was significantly reduced compared to healthy individuals by an average of 13.2% in CD, 14.2% in CC, and 8.4% in DCP in all patient groups. In ICP, the reduction was 9.2% for RPnE and 12.7% for RPwE patients. The SVC showed reduced FL in the MD (8.1%) and RPnE (10.3%) group.
Conclusions
OCT-A is a valuable tool to examine retinal vascular abnormalities in patients with MD and RP. OCT-A revealed a reduced flow in various retinal layers in MD, RPnE, and RPwE. Alterations of the FAZ were less distinct in these groups which add to the variation reported previously.
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.
Introduction
Mutations in the peripherin-2 gene (
PRPH2
) are a common cause of inherited retinal dystrophies well known for their phenotypic diversity. We describe a novel presentation of the c.623G ...> A; p.(Gly208Asp) variant in association with cone-rod dystrophy and reduced penetrance.
Case description
A 39-year-old man presents with a history of decreased visual acuity, photophobia, and dyschromatopsia. Fundus examination was largely unremarkable while spectral-domain optical coherence tomography (SD-OCT) demonstrated diffuse granularity at the ellipsoid zone. Full-field electroretinogram (ffERG) revealed a cone-rod dystrophy. Genetic testing revealed a heterozygous pathogenic variant, c.623G > A; p.(Gly208Asp), in the
PRPH2
gene, also found in an unaffected brother. The 50-year-old brother had no visual symptoms and no findings on fundus examination. SD-OCT showed normal retinal architecture and ffERG was within normal limits bilaterally.
Conclusion
This case report broadens the known phenotypic presentations of
PRPH2
-associated retinopathy and suggests that the
PRPH2
variant c.623G > A; p.(Gly208Asp) may be associated with reduced penetrance.
Introduction:
Mutations in the cone-rod homeobox (CRX) gene, a known cause of inherited retinal dystrophy, are characterized by extensive phenotypic heterogeneity. We describe a novel presentation of ...rod-cone dystrophy (RCD) phenocopying pigmented paravenous retinochoroidal atrophy associated with a mutation in CRX.
Case description:
A 53-year-old man and his 48-year-old brother presented with a history of progressive vision loss and nyctalopia. Fundus examination revealed a bull’s eye lesion with chorioretinal atrophy and intraretinal pigment migration, while spectral-domain optical coherence tomography (SD-OCT) demonstrated retinal thinning with outer retinal atrophy. On short-wavelength autofluorescence (SW-AF) imaging, an atypical paravenous pattern of atrophy with a surrounding hyperautofluorescent border was observed. Full-field electroretinogram (ffERG) revealed a rod-cone pattern of dysfunction. A heterozygous pathogenic variant, c.119G>A:p.(Arg40Gln), in the CRX gene was identified in both brothers and segregated in their family.
Conclusion:
This case report broadens the currently known phenotypic presentations of CRX-associated retinopathy and suggests that mutations in CRX may be associated with pigmented paravenous retinochoroidal atrophy.
Aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) is expressed in photoreceptors where it facilitates the assembly of phosphodiesterase 6 (PDE6) which hydrolyses cGMP within the ...phototransduction cascade. Genetic variations in
cause type 4 Leber congenital amaurosis (LCA4), which presents as rapid loss of vision in early childhood. Limited in vitro LCA4 models are available, and these rely on patient-derived cells harbouring patient-specific
mutations. While valuable, the use and scalability of individual patient-derived LCA4 models may be limited by ethical considerations, access to patient samples and prohibitive costs. To model the functional consequences of patient-independent
mutations, CRISPR/Cas9 was implemented to produce an isogenic induced pluripotent stem cell line harbouring a frameshift mutation in the first exon of
. Retinal organoids were generated using these cells, which retained
gene transcription, but AIPL1 protein was undetectable. AIPL1 knockout resulted in a decrease in rod photoreceptor-specific PDE6α and β, and increased cGMP levels, suggesting downstream dysregulation of the phototransduction cascade. The retinal model described here provides a novel platform to assess functional consequences of AIPL1 silencing and measure the rescue of molecular features by potential therapeutic approaches targeting mutation-independent pathogenesis.
The inherited retinal dystrophies (IRDs) are a clinically and genetically complex group of disorders primarily affecting the rod and cone photoreceptors or other retinal neuronal layers, with ...emerging therapies heralding the need for accurate molecular diagnosis. Targeted capture and panel-based strategies examining the partial or full exome deliver molecular diagnoses in many IRD families tested. However, approximately one in three families remain unsolved and unable to obtain personalised recurrence risk or access to new clinical trials or therapy. In this study, we investigated whole genome sequencing (WGS), focused assays and functional studies to assist with unsolved IRD cases and facilitate integration of these approaches to a broad molecular diagnostic clinical service. The WGS approach identified variants not covered or underinvestigated by targeted capture panel-based clinical testing strategies in six families. This included structural variants, with notable benefit of the WGS approach in repetitive regions demonstrated by a family with a hybrid gene and hemizygous missense variant involving the opsin genes,
and
. There was also benefit in investigation of the repetitive GC-rich ORF15 region of
. Further molecular investigations were facilitated by focused assays in these regions. Deep intronic variants were identified in
and
, with functional RNA based studies of the
variant revealing activation of a cryptic splice acceptor site. While targeted capture panel-based methods are successful in achieving an efficient molecular diagnosis in a proportion of cases, this study highlights the additional benefit and clinical value that may be derived from WGS, focused assays and functional genomics in the highly heterogeneous IRDs.
-associated retinopathy is a rare inherited retinal dystrophy, and its outcome has not been determined. A single retinal involvement by a mutation of the
gene is unexplained. We found three unrelated ...patients with a disease-causing
variant in a biallelic state from 1555 Japanese individuals of 1314 families with inherited retinal dystrophy. We reviewed their medical records and examined their peripheral lymphocytes by transmission electron microscopy (TEM).
was a 38-year-old woman who complained of night blindness and reduced vision. She developed macular degeneration at age 43 years.
and
were a man and a woman both of whom noticed night blindness in their 30s. Both had a degeneration in the macula and midperiphery in their 40s, which progressed to a diffuse retinal degeneration in their 60s when their vision was reduced to hand motions. Three novel
variants were identified. TEM of the lymphocytes of
and
showed abnormal structures in 40.6% and 0.3% of the peripheral lymphocytes, respectively. We concluded that the
-associated retinopathy of our patients was a progressive rod-cone dystrophy, and the visual outcome was poor. The systemic effect of
mutations may be compensable and have variations.
Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerations and pathogenic variants in the Rhodopsin (RHO) gene are major cause for autosomal dominant RP (adRP). Despite ...extensive attempts to treat RHO-associated adRP, standardized curative treatment is still lacking. Recently developed base editors offer an exciting opportunity to correct pathogenic single nucleotide variants and are currently able to correct all transition variants and some transversion variants. In this study, we analyzed previously reported pathogenic RHO variants (n = 247) for suitable PAM sites for currently available base editors utilizing the Streptococcus pyogenes Cas9 (SpCas9), Staphylococcus aureus Cas9 (SaCas9) or the KKH variant of SaCas9 (KKH-SaCas9) to assess DNA base editing as a treatment option for RHO-associated adRP. As a result, 55% of all the analyzed variants could, in theory, be corrected with base editors, however, PAM sites were available for only 32% of them and unwanted bystander edits were predicted for the majority of the designed guide RNAs. As a conclusion, base editing offers exciting possibilities to treat RHO-associated adRP in the future, but further research is needed to develop base editing constructs that will provide available PAM sites for more variants and that will not introduce potentially harmful bystander edits.
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