Gene augmentation of LCA5-associated Leber congenital amaurosis ameliorates bulge region defects of the photoreceptor ciliary axoneme.

Leber congenital amaurosis (LCA) is a group of inherited retinal diseases characterized by early-onset, rapid loss of photoreceptor cells. Despite the discovery of a growing number of genes associated with this disease, the molecular mechanisms of photoreceptor cell degeneration of most LCA subtypes remain poorly understood. Here, using retina-specific affinity proteomics combined with ultrastructure expansion microscopy, we reveal the structural and molecular defects underlying LCA type 5 (LCA5) with nanoscale resolution.

Applications of antisense oligonucleotides for the treatment of inherited retinal diseases.

Purpose Of Review: Over the last years, antisense oligonucleotides (AONs) have gained attention as a therapeutic tool for the treatment of ocular diseases such as cytomegalovirus retinitis, keratitis-induced corneal neovascularization, and inherited retinal diseases (IRDs). In this review, we summarize the recent key findings, and describe the challenges and opportunities that lie ahead to translate AON-based therapies to the clinic, in particular for IRDs.

Recent Findings: The efficacy of AONs to restore splice defects and cellular phenotypes associated with a common mutation in CEP290 was demonstrated in patient-derived optic cups and in a transgenic mouse model, respectively.

Mutations in AGBL5, Encoding α-Tubulin Deglutamylase, Are Associated With Autosomal Recessive Retinitis Pigmentosa.

Purpose: AGBL5, encoding ATP/GTP binding protein-like 5, was previously proposed as an autosomal recessive retinitis pigmentosa (arRP) candidate gene based on the identification of missense variants in two families. In this study, we performed next-generation sequencing to reveal additional RP cases with AGBL5 variants, including protein-truncating variants.

Methods: Whole-genome sequencing (WGS) or whole-exome sequencing (WES) was performed in three probands.

Antisense Oligonucleotide-based Splice Correction for USH2A-associated Retinal Degeneration Caused by a Frequent Deep-intronic Mutation.

Usher syndrome (USH) is the most common cause of combined deaf-blindness in man. The hearing loss can be partly compensated by providing patients with hearing aids or cochlear implants, but the loss of vision is currently untreatable. In general, mutations in the USH2A gene are the most frequent cause of USH explaining up to 50% of all patients worldwide.

In vitro and in vivo rescue of aberrant splicing in CEP290-associated LCA by antisense oligonucleotide delivery.

Leber congenital amaurosis (LCA) is a severe disorder resulting in visual impairment usually starting in the first year of life. The most frequent genetic cause of LCA is an intronic mutation in CEP290 (c.2991 + 1655A > G) that creates a cryptic splice donor site resulting in the insertion of a pseudoexon (exon X) into CEP290 mRNA.

Photoreceptor Progenitor mRNA Analysis Reveals Exon Skipping Resulting from the ABCA4 c.5461-10T→C Mutation in Stargardt Disease.

Purpose: To elucidate the functional effect of the ABCA4 variant c.5461-10T→C, one of the most frequent variants associated with Stargardt disease (STGD1).

Design: Case series.

Comprehensive genotyping reveals RPE65 as the most frequently mutated gene in Leber congenital amaurosis in Denmark.

Leber congenital amaurosis (LCA) represents the most severe form of inherited retinal dystrophies with an onset during the first year of life. Currently, 21 genes are known to be associated with LCA and recurrent mutations have been observed in AIPL1, CEP290, CRB1 and GUCY2D. In addition, sequence analysis of LRAT and RPE65 may be important in view of treatments that are emerging for patients carrying variants in these genes.

A Nonsense Mutation in FAM161A Is a Recurrent Founder Allele in Dutch and Belgian Individuals With Autosomal Recessive Retinitis Pigmentosa.

Purpose: To identify mutations in FAM161A underlying autosomal recessive retinitis pigmentosa (arRP) in the Dutch and Belgian populations and to investigate whether common FAM161A-associated phenotypic features could be identified.

Methods: Homozygosity mapping, amplification-refractory mutation system (ARMS) analysis, and Sanger sequencing were performed to identify mutations in FAM161A. Microsatellite and SNP markers were genotyped for haplotype analysis.

Antisense Oligonucleotide Therapy for Inherited Retinal Dystrophies.

Inherited retinal dystrophies (IRDs) are an extremely heterogeneous group of genetic diseases for which currently no effective treatment strategies exist. Over the last decade, significant progress has been made utilizing gene augmentation therapy for a few genetic subtypes of IRD, although several technical challenges so far prevent a broad clinical application of this approach for other forms of IRD. Many of the mutations leading to these retinal diseases affect pre-mRNA splicing of the mutated genes .

The efficacy of microarray screening for autosomal recessive retinitis pigmentosa in routine clinical practice.

Purpose: To determine the efficacy of multiple versions of a commercially available arrayed primer extension (APEX) microarray chip for autosomal recessive retinitis pigmentosa (arRP).

Methods: We included 250 probands suspected of arRP who were genetically analyzed with the APEX microarray between January 2008 and November 2013. The mode of inheritance had to be autosomal recessive according to the pedigree (including isolated cases).

Variants in Nebulin (NEB) Are Linked to the Development of Familial Primary Angle Closure Glaucoma in Basset Hounds.

Several dog breeds are susceptible to developing primary angle closure glaucoma (PACG), which suggests a genetic basis for the disease. We have identified a four-generation Basset Hound pedigree with characteristic autosomal recessive PACG that closely recapitulates PACG in humans. Our aim is to utilize gene mapping and whole exome sequencing approaches to identify PACG-causing sequence variants in the Basset.

The pros and cons of vertebrate animal models for functional and therapeutic research on inherited retinal dystrophies.

Over the last decade, huge progress has been made in the understanding of the molecular mechanisms underlying inherited retinal dystrophy (IRD), as well as in the development and implementation of novel therapies, especially in the field of gene therapy. The use of mutant animal models, either naturally occurring or generated by genetic modification, have contributed greatly to our knowledge on IRD. Yet, these mutant animal models do not always mimic the retinal phenotype that is observed in humans with mutations in the orthologous gene, often due to species-specific characteristics of the retina, and/or diverse functions of the gene products in different species.

Autosomal recessive retinitis pigmentosa with RP1 mutations is associated with myopia.

Objective: To determine the refractive error in patients with autosomal recessive retinitis pigmentosa (arRP) caused by RP1 mutations and to compare it with that of other genetic subtypes of RP.

Methods: Twenty-six individuals had arRP with RP1 mutations, 25 had autosomal dominant RP (adRP) with RP1 mutation, 8 and 33 had X-linked RP (xlRP) with RP2 and RPGR mutations, respectively, 198 and 93 had Usher syndrome and arRP without RP1 mutations, respectively. The median of the spherical equivalent (SE) and the IQR (Q25-Q75) was determined and multiple comparisons were performed.

Whole-exome sequencing reveals ZNF408 as a new gene associated with autosomal recessive retinitis pigmentosa with vitreal alterations.

Retinitis pigmentosa (RP) is a group of progressive inherited retinal dystrophies that cause visual impairment as a result of photoreceptor cell death. RP is heterogeneous, both clinically and genetically making difficult to establish precise genotype-phenotype correlations. In a Spanish family with autosomal recessive RP (arRP), homozygosity mapping and whole-exome sequencing led to the identification of a homozygous mutation (c.

Species-dependent splice recognition of a cryptic exon resulting from a recurrent intronic CEP290 mutation that causes congenital blindness.

A mutation in intron 26 of CEP290 (c.2991+1655A>G) is the most common genetic cause of Leber congenital amaurosis (LCA), a severe type of inherited retinal degeneration. This mutation creates a cryptic splice donor site, resulting in the insertion of an aberrant exon (exon X) into ~50% of all CEP290 transcripts.

Novel insights into the molecular pathogenesis of CYP4V2-associated Bietti's retinal dystrophy.

Bietti's crystalline dystrophy (BCD) is a rare, autosomal recessive retinal degenerative disease associated with mutations in CYP4V2. In this study, we describe the genetic and clinical findings in 19 unrelated BCD patients recruited from five international retinal dystrophy clinics. Patients underwent ophthalmic examinations and were screened for CYP4V2 mutations by Sanger sequencing and quantitative polymerase chain reaction (qPCR) copy number variation screening.

Retinitis pigmentosa caused by mutations in the ciliary MAK gene is relatively mild and is not associated with apparent extra-ocular features.

Purpose: Defects in MAK, encoding a protein localized to the photoreceptor connecting cilium, have recently been associated with autosomal recessive retinitis pigmentosa (RP). The aim of this study is to describe our detailed clinical observations in patients with MAK-associated RP, including an assessment of syndromic symptoms frequently observed in ciliopathies.

Methods: In this international collaborative study, 11 patients carrying nonsense or missense mutations in MAK were clinically evaluated, including extensive assessment of the medical history, slit-lamp biomicroscopy, ophthalmoscopy, kinetic perimetry, electroretinography (ERG), spectral-domain optical coherence tomography (SD-OCT), autofluorescence imaging and fundus photography.

Mutations in IFT172 cause isolated retinal degeneration and Bardet-Biedl syndrome.

Primary cilia are sensory organelles present on most mammalian cells. The assembly and maintenance of primary cilia are facilitated by intraflagellar transport (IFT), a bidirectional protein trafficking along the cilium. Mutations in genes coding for IFT components have been associated with a group of diseases called ciliopathies.

Novel compound heterozygous NMNAT1 variants associated with Leber congenital amaurosis.

Purpose: The gene encoding nicotinamide nucleotide adenylyltransferase 1 (NMNAT1) was recently found to be mutated in a subset of patients with Leber congenital amaurosis (LCA) with macular atrophy. The aim of this study was to determine the occurrence and frequency of NMNAT1 mutations and associated phenotypes in different types of inherited retinal dystrophies.

Methods: DNA samples of 161 patients with LCA without genetic diagnosis were analyzed for variants in NMNAT1 using Sanger sequencing.

Genomic approaches for the discovery of genes mutated in inherited retinal degeneration.

In view of their high degree of genetic heterogeneity, inherited retinal diseases (IRDs) pose a significant challenge for identifying novel genetic causes. Thus far, more than 200 genes have been found to be mutated in IRDs, which together contain causal variants in >80% of the cases. Accurate genetic diagnostics is particularly important for isolated cases, in which X-linked and de novo autosomal dominant variants are not uncommon.

IMPG2-associated retinitis pigmentosa displays relatively early macular involvement.

Purpose: To provide the first detailed clinical description in patients with RP caused by recessive mutations in IMPG2.

Methods: This international collaborative study includes 17 RP patients with inherited retinal disease caused by mutations in IMPG2. The patients were clinically (re-)examined, including extensive medical history taking, slit-lamp biomicroscopy, ophthalmoscopy, perimetry, ERG, optical coherence tomography (OCT), fundus autofluorescence (FAF) imaging, fundus photography, and color vision tests.

Nonpenetrance of the most frequent autosomal recessive leber congenital amaurosis mutation in NMNAT1.

Importance: The NMNAT1 gene was recently found to be mutated in a subset of patients with Leber congenital amaurosis and macular atrophy. The most prevalent NMNAT1 variant was p.Glu257Lys, which was observed in 38 of 106 alleles (35.

A missense mutation in the splicing factor gene DHX38 is associated with early-onset retinitis pigmentosa with macular coloboma.

Background: Retinitis pigmentosa (RP) is the most frequent inherited retinal disease, which shows a relatively high incidence of the autosomal-recessive form in Pakistan.

Methods: Genome-wide high-density single-nucleotide polymorphism (SNP) microarrays were used to identify homozygous regions shared by affected individuals of one consanguineous family. DNA of three affected and two healthy siblings was used for SNP genotyping.