Novel causative variants in patients with achromatopsia

ABSTRACT

Purpose: To report five novel genetic variants in seven unrelated consanguineous families with achromatopsia (ACHM).

Methods: Patients were examined with multimodal retinal imaging and full-field electroretinography (ffERG). Genetic testing was conducted using next-generation sequencing (NGS).

Results: Three novel homozygous variants were detected in CNGA3: a missense c.967G > C (p.Ala323Pro) variant was detected in exon 8 (one patient), a splice site variant c.101 + 1G > A in intron 2 (three patients), and a splice site variant c.395 + 1G > T in intron 4(one patient). Another two novel variants were found in PDE6C: a homozygous missense variant c.1899C > A (p.His633Gln) in exon 15 (one patient) and a homozygous splice site variant c.1072-1G > C in intron 7 (one patient). Mutation segregation assessment was possible in 3 of the 7 families. All patients had nonrecordable ffERG 30-Hz flicker responses, reduced single-flash cone responses but preserved rod responses. Patients presented with variable degrees of foveal outer retinal layer loss and variable patterns of foveal hyperautofluorescence.

Conclusions: These novel variants expand the genotypes associated with ACHM and may help in future therapy development for ACHM.     

Correlation between visual acuity and OCT-measured retinal nerve fiber layer thickness in a family with ADOA and an OPA1 mutation

Purpose: To assess the association between retinal nerve fiber layer (RNFL) thickness and visual acuity in a family from Siracusa (Sicily) with autosomal dominant optic atrophy (ADOA) due to a heterozygous c.869G>A OPA1 mutation.

Methods: Affected family members underwent complete neuro-ophthalmological evaluation, including visual acuity testing, colour vision testing, tonometry, visual field testing, colour fundus photography, pattern visual-evoked potential (PVEP) testing, and pattern electroretinography (PERG). Patients and age-matched control subjects were scanned by spectral-domain optical coherence tomography (SD-OCT) to assess circumpapillary RNFL thickness.

Results: All patients showed the characteristic optic disc pallor and central scotomas in the visual field. PVEP testing and PERG also showed alterations consistent with ADOA. The average circumpapillary RNFL thickness was thinner in ADOA patients than in control subjects (60.87?±?6.58µm and 108.13?±?6.53µm, respectively; p = 0.0001). The visual acuity in patients with ADOA correlated significantly with the circumpapillary average RNFL thickness (r = ?0.845, p = 0.008).

Conclusions: OCT-measured peripapillary RNFL thickness is reduced in ADOA patients compared with healthy subjects and correlates significantly with visual acuity in patients with ADOA. The photoreceptor layers are morphologically unaffected.     

Ocular Features in Chinese Patients with Blau Syndrome

ABSTRACT

Purpose: To identify pathogenic gene variants in the NOD2 gene and assess the clinical features of a cohort of Chinese patients affected with Blau syndrome.

Methods: Eight patients from seven unrelated families were enrolled. Detailed ophthalmological examinations were performed. Sanger sequencing was used to analyze the NOD2 gene.

Results: The onset age of ocular manifestations varied from 2 to 24 years (median: 5.5 years). Best corrected visual acuity (BCVA) ranged from light perception (LP) to 1.0. One patient presented with recurrent anterior uveitis, six patients had panuveitis and one patient was at the phthisis bulbi stage. One novel disease-associated variant (c.2006A>G, p.His669Arg) and four previously reported disease-causing variants (c.1000C>T, p.Arg334Trp; c.1001G>A, p.Arg334Gln; c.1442G>A, p.Gly481Asp; c.1759C>T, p.Arg587Cys) in the NOD2 gene (NM_022162.1) were identified.

Conclusions: Blau syndrome is a rare autosomal dominant multisystem disease caused by a NOD2 gene defect. Recurrent anterior uveitis and/or panuveitis are the characteristic ocular findings.     

A novel OPA1 mutation responsible for autosomal dominant optic atrophy with high frequency hearing loss in a Chinese family

PURPOSE: To investigate the genetic findings and phenotypic characters of autosomal dominant optic atrophy (ADOA). DESIGN: Case report and experimental study. METHODS: Molecular genetic analysis and clinical examinations were performed in a Chinese family with ADOA. Mutations in OPA1 were detected by direct sequencing. Haplotypes were constructed and compared with the phenotypes in the family. RESULTS: Nine family members were diagnosed with ADOA and some of them were accompanied with hearing loss and/or high myopia. A novel heterozygous mutation, c.2848_2849delGA(p.Asp950CysfsX4), was detected in all ADOA patients. The mutation and the mutation bearing haplotype cosegregated with the nine affected members. One family member had high myopia without vision or hearing loss. This patient along with unaffected ones did not harbor the mutation. CONCLUSIONS: A novel mutation, c.2848_2849delGA in OPA1, was identified in a Chinese family with ADOA. This mutation is associated with hearing loss, but likely not high myopia.     

Targeted next-generation sequencing reveals that a compound heterozygous mutation in phosphodiesterase 6a gene leads to retinitis pigmentosa in a Chinese family

Purpose: Retinitis pigmentosa (RP) is a genetically heterogeneous disease with over 70 causative genes identified to date. However, approximately 40% of RP cases remain genetically unsolved, suggesting that many novel disease-causing mutations are yet to be identified. The purpose of this study is to identify the causative mutations of a Chinese RP family.

Methods: Targeted next-generation sequencing (NGS) for a total of 163 genes which involved in inherited retinal disorders were used to screen the possible causative mutations. Sanger sequencing was used to verify the mutations.

Results: As results, we identified two heterozygous mutations: a splicing site mutation c.1407 + 1G>C and a nonsense mutation c. 1957C>T (p.R653X) in phosphodiesterase 6A (PDE6A) gene in the RP patient. These two mutations are inherited from his father and mother, respectively. Furthermore, these mutations are unique in our in-house database and are rare in human genome databases, implicating that these two mutations are pathological.

Conclusion: By using targeted NGS method, we identified a compound heterozygous mutation in PDE6A gene that is associated with RP in a Chinese family.     

Role of the tissue-type plasminogen activator -7351C > T and plasminogen activator inhibitor 1 4G/5G gene polymorphisms in central serous chorioretinopathy

ABSTRACT

Background: Central serous chorioretinopathy (CSC) is a common chorioretinal disease, characterized by choroidal hyperpermeability leading to neurosensory and/or retinal pigment epithelial detachments. Hypofibrinolysis due to higher plasma concentrations of plasminogen activator type 1 (PAI-1) or lower activity of tissue-type plasminogen activator (t-PA) has been implicated in the pathogenesis of CSC. Functional polymorphisms in the PAI-1 (SERPINE1) and t-Pa (PLAT) are thus potential risk factors for CSC. The aim of the present study was therefore to investigate a hypothesized association between the PAI-1 4G/5G and the t-PA -7351C > T gene variants and the presence of CSC.

Methods: The present study comprised 172 CSC patients and 313 control subjects. Genotypes of the PAI-1 4G/5G and the t-PA -7351C > T polymorphisms were determined by TaqMan^TM fluorogenic 5′-exonuclease assays.

Results: Allelic frequencies or genotype distributions of neither the PAI-1 4G/5G nor the t-PA -7531C > T polymorphisms were significantly different between patients with CSC and control subjects (PAI-1 4G/4G: 24.4% vs. 20.4, p = 0.36; t-PA -7351CC: 42.4% vs. 46.0%, p = 0.50). After adjusting for age and gender presence of the PAI-1 4G/4G genotype was associated with a non-significant odds ratio (OR) of 1.21 (95% confidence interval [95% CI]: 0.77–1.92, p = 0.41), while homozygosity for the t-PA -7351C allele yielded a non-significant OR of 0.91 (95% CI: 0.62–1.33, p = 0.62) for CSC.

Conclusion: The present study suggests that both the t-PA -7351C > T and the PAI-1 4G/5G gene variants are unlikely major risk factors for CSC.     

Novel mutations in the OPN1LW and NR2R3 genes in a patient with blue cone monochromacy

Background: To clarify the diagnosis of a Chinese patient with novel double heterozygous in the NR2E3 and OPN1LW genes and describe the clinical features.

Materials and Methods: A 47-year-old man presented with an 8-year history of decreased vision and poor night vision. Based on his clinical phenotype, we focused on 36 genes associated with these characteristics. Possible pathogenic mutation sites were screened by next-generation sequencing (NGS), which showed novel mutations in the NR2E3 and OPN1LW genes. These mutations were confirmed in the patient’s sister and daughter by Sanger sequencing. To clarify the diagnosis, the clinical symptoms of the patient were observed and analyzed in combination with comprehensive ophthalmologic examinations.

Results: Genetic analysis identified the presence of novel double heterozygous of c.361G>A; p.E121K in NR2E3, a gene responsible for enhanced S-cone syndrome (ESCS; OMIM #268100) and c.244A>G; p.K82E in OPN1LW, a gene responsible for blue cone monochromacy (BCM; OMIM#303700). No typical clinical presentation or fundus features were found. The differential diagnosis of ESCS was excluded by electroretinography (ERG) due to the lack of characteristic abnormalities associated with ESCS. Based on the clinical manifestations and comprehensive ophthalmologic examinations, the patient was diagnosed with BCM.

Conclusions: The novel mutations of c.244A>G; p.K82E in the OPN1LW gene and c.361G>A; p.E121K in the NR2E3 gene both cause BCM, but OPN1LW gene mutation dominated the retinal degeneration, resulting in the clinical features observed in this patient. These novel double heterozygous may be helpful for future genetic diagnosis and treatment for BCM.     

常染色体显性视神经萎缩研究进展

常染色体显性视神经萎缩（ADOA）,又称为Kjer型视神经萎缩,是显性遗传性视神经疾病中最常见的一种,其发病率为1：10000～1：50000。其主要的临床表现为视力下降、色觉障碍、视野缺损等,特征性的眼底改变为颞侧视盘苍白。本病还可以伴随听力下降、白内障、眼外肌麻痹、上睑下垂等。目前,已发现的ADOA候选基因位点包括OPA1（3q28—29）、OPA3（19q13．2—13．3）、OPA4（18q12．2—12．3）和OPA5（22q12．1—13．1）等。其中,OPA1与OPA3位点均已克隆出相应的同名基因,但本病的基因型与表型的关系及致病机制还不十分明确。就ADOA的临床表现、与ADOA相关的侯选基因、位点及其鉴别诊断的最新研究进行总结。     

Slowly progressive retinitis pigmentosa caused by two novel mutations in the MAK gene

Background: The growing number of clinical trials currently underway for inherited retinal diseases has highlighted the importance of achieving a molecular diagnosis for all new cases presenting to hospital eye services. The male germ cell-associated kinase (MAK) gene encodes a cilium-associated protein selectively expressed in the retina and testis, and has recently been implicated in autosomal recessive retinitis pigmentosa (RP). Whole exome sequencing has previously identified a homozygous Alu insertion in probands with recessive RP and nonsense and missense mutations have also been reported.

Materials and methods: Here we describe two novel mutations in different alleles of the MAK gene in a 75-year-old British female, who had a clinical diagnosis of RP () with onset in the fourth decade and no relevant family history. The mutations were established through next generation sequencing of a panel of 111 genes associated with RP and RP-like phenotypes.

Results: Two novel null mutations were identified within the MAK gene. The first c.1195_1196delAC p.(Thr399fs), was a two base-pair deletion creating a frame-shift in exon 9 predicted to result in nonsense-mediated decay. The second, c.279-2A>G, involved the splice acceptor consensus site upstream of exon 4, predicted to lead to aberrant splicing.

Conclusions: The natural history of this individual’s RP is consistent with previously described MAK mutations, being significantly milder than that associated with other photoreceptor ciliopathies. We suggest inclusion of MAK as part of wider genetic testing in all individuals presenting with RP.     

OPA1 mutations in Japanese patients suspected to have autosomal dominant optic atrophy

Purpose  

To report three types of heterozygous mutations in the OPA1 gene in five patients from three families with autosomal dominant optic atrophy (ADOA, MIM#165500).     

Structural model of the OPA1 GTPase domain may explain the molecular consequences of a novel mutation in a family with autosomal dominant optic atrophy

Autosomal dominant optic atrophy (ADOA) is the most frequent hereditary optic neuropathy. Three loci have been reported for ADOA: a major locus, harboring all identified mutations to date, maps to 3q28 (OPA1), a second locus is linked to 18q12.2-q12.3 (OPA4) and a third locus on 22q12.1-q13.1 (OPA5) has been reported recently. We describe a six-generation Iranian family in which optic atrophy runs as an autosomal dominant trait with an age of onset at 14-15years. We performed linkage analysis with markers mapping to 3q28 and 18q12.2-q12.3 and found linkage to 3q28. Subsequent sequencing of OPA1 identified a novel heterozygous missense mutation (c.1313A>G) replacing aspartic acid by glycine (p.D438G) in the GTPase domain of OPA1. Interestingly, another missense mutation at the same position (c.1313A>T, D438V) has been reported before in two unrelated German families, indicating a possible mutation hot spot. Further evidence supporting the importance of D438 is its conservation from human to acoelomata. OPA1 is believed to be the human orthologue of yeast MGM1, a dynamin-related protein required for the integrity of mitochondrial DNA. Homology modeling of the OPA1 GTPase domain revealed extensive structural similarity to the Dictyostelium dynamin A GTPase domain and showed that D438 may interact with residues of the G1 and the G4 motifs, which are crucial in coordinating GTP. Based on this analysis, we propose a mechanism which explains the gradual decline of vision in ADOA patients with OPA1 mutations at position 438.     

Novel homozygous OPA3 mutation in an Afghani family with 3-methylglutaconic aciduria type III and optic atrophy

ABSTRACT

Purpose: To describe and distinguish clinical phenotypes with the overlapping feature of optic atrophy caused by distinct mutations in the same gene, OPA3. We report 3 affected siblings in a consanguineous family harboring a novel OPA3 mutation causing 3-methylglutaconic aciduria type III with optic atrophy.

Methods: Retrospective case series.

Results: Three siblings (2 male, 1 female) among 6 children in a consanguineous Afghani family developed decreased vision from early childhood. Both parents and all extended family members were unaffected. All 3 affected siblings suffered from severe visual impairment ranging from visual acuities of 20/150 to counting fingers. All had spastic lower extremity weakness and ataxia. Two of the three affected siblings also had a history of seizures, and the female sibling had limited cognition with diffuse atrophic changes on brain MRI. Two of the three individuals also had migraine-like headaches. Urine organic acid analysis revealed mildly elevated 3-methylglutaconic acid for the male siblings. Whole exome sequencing and subsequent PCR confirmation revealed a novel variant in OPA3 (intron1, c.142 + 2_142 + 3dupTG), affecting the consensus sequence of the splice site, for which all 3 clinically affected siblings were homozygous.

Discussion: Mutations in OPA3 can cause optic atrophy in a dominant pattern of inheritance associated with cataract or in a recessive pattern associated with spastic paresis and ataxia. The novel recessive mutation and clinical presentations described herein further support how different mutation types affecting OPA3 can produce distinct clinical phenotypes and underscore the critical and susceptible role of mitochondrial health in optic nerve function.     

Genetic screening of Russian Usher syndrome patients toward selection for gene therapy

ABSTRACT

Background: Usher syndrome (USH) is heterogeneous in nature and requires genetic test for diagnosis and management. Mutations in USH associated genes are reported in some populations except Russians. Here, we first time represented the mutation spectrum of a Russian USH cohort.

Methods: Twenty-eight patients with USH were selected from 3214 patients from Deaf-Blind Support Foundation “Con-nection” during 2014–2016 following the observational study NCT03319524. Complete ophthalmologic, ENT, and vestibular medical tests were done for clinical characterization. NGS, MLPA, and Sanger sequencing were considered for genetic analysis.

Results: Around 53.57% and 39.28% patients had USH1 and USH2, respectively; 17.85% cases (n = 5/28) had no known mutation. Eleven (73.33%) subjects showed variations in USH1 associated genes MYO7A (72.72%), CDH23 (9.09%), PCDH15 (9.09%), and USH1C (9.09%). Eleven mutations are detected in MYO7A where 54.54% are novel. MYO7A: p.Q18* was most frequent (27.27%) mutation and is associated with early manifestation and most severe clinical picture. Two novel mutations (p.E1301* and c.158-?_318+?del) are detected in PCDH15 gene. Around 90.90% patients suspected to be USH2 are confirmed by genetic testing. Eleven mutations detected in the USH2A gene, where 27.27% were novel. Most common USH2A mutation is p.W3955* (50%) followed by p.E767fs, p.R1653*, and c.8682-9A> G (20% each).

Conclusion: The Russian USH cohort shows both novel and known USH mutations. Clinically the prevalence of USH2 is low (39.28%) and the frequency of MYO7A mutations responsible for USH1B is very high (63.63%, N = 7/11) compared to other cohorts. These seven patients carrying MYO7A mutations are preliminarily eligible for the UshStat® gene therapy.     

CEP250 mutations associated with mild cone-rod dystrophy and sensorineural hearing loss in a Japanese family

Background: CEP250 encodes the C-Nap1 protein which belongs to the CEP family of proteins. C-Nap1 has been reported to be expressed in the photoreceptor cilia and is known to interact with other ciliary proteins. Mutations of CEP250 cause atypical Usher syndrome which is characterized by early-onset sensorineural hearing loss (SNHL) and a relatively mild retinitis pigmentosa. This study tested the hypothesis that the mild cone-rod dystrophy (CRD) and SNHL in a non-consanguineous Japanese family was caused by CEP250 mutations.

Methods: Detailed ophthalmic and auditory examinations were performed on the proband and her family members. Whole exome sequencing (WES) was used on the DNA obtained from the proband.

Results: Electrophysiological analysis revealed a mild CRD in two family members. Adaptive optics (AO) imaging showed reduced cone density around the fovea. Auditory examinations showed a slight SNHL in both patients. WES of the proband identified compound heterozygous variants c.361C>T, p.R121*, and c.562C>T, p.R188* in CEP250. The variants were found to co-segregate with the disease in five members of the family.

Conclusions: The variants of CEP250 are both null variants and according to American College of Medical Genetics and Genomics (ACMG) standards and guideline, these variants are classified into the very strong category (PVS1). The criteria for both alleles will be pathogenic. Our data indicate that mutations of CEP250 can cause mild CRD and SNHL in Japanese patients. Because the ophthalmological phenotypes were very mild, high-resolution retinal imaging analysis, such as AO, will be helpful in diagnosing CEP250-associated disease.     

Molecular characterization of Axenfeld-Rieger spectrum and other anterior segment dysgeneses in a sample of Mexican patients

ABSTRACT

Background: Anterior segment dysgenesis (ASD) and Axenfeld-Rieger spectrum (ARS) are mainly due to PITX2 and FOXC1 defects, but it is difficult in some patients to differentiate among PITX2-, FOXC1-, PAX6- and CYP1B1-related disorders. Here, we set out to characterize the pathogenic variants (PV) in PITX2, FOXC1, CYP1B1 and PAX6 in nine unrelated Mexican ARS/ASD patients and in their available affected/unaffected relatives.

Materials and methods: Automated Sanger sequencing of PITX2, FOXC1, PAX6 and CYP1B1 was performed; those patients without a PV were subsequently analyzed by Multiplex Ligation-dependent Probe Amplification (MLPA) for PITX2, FOXC1 and PAX6. Missense variants were evaluated with the MutPred, Provean, PMUT, SIFT, PolyPhen-2, CUPSAT and HOPE programs.

Results: We identified three novel PV in PITX2 (NM_153427.2:c.217G>A, c.233T>C and c.279del) and two in FOXC1 [NM_001453.2:c.274C>T (novel) and c.454T>A] in five ARS patients. The previously reported FOXC1 c.367C>T or p.(Gln123*) variant was identified in a patient with ASD. The ocular phenotype related to FOXC1 included aniridia, corneal opacity and early onset glaucoma, while an asymmetric ocular phenotype and aniridia were associated with PITX2. No gene rearrangements were documented by MLPA analysis, nor were any PV identified in PAX6 or CYP1B1.

Conclusions: Heterozygous PV in the PITX2 and FOXC1 genes accounted for 66% (6/9) of the ARS/ASD cases. The absence of PAX6 or CYP1B1 abnormalities could reflect our small sample size, although their analysis could be justified in ARS/ASD patients that present with congenital glaucoma or aniridia.     

Whole genome sequencing reveals novel mutations causing autosomal dominant inherited macular degeneration

ABSTRACT

Background: Age-related macular degeneration (AMD) is a common sight threatening condition. However, there are a number of monogenic macular dystrophies that are clinically similar to AMD, which can potentially provide pathogenetic insights.

Methods: Three siblings from a non-consanguineous Greek-Cypriot family reported central visual disturbance and nyctalopia. The patients had full ophthalmic examinations and color fundus photography, spectral-domain ocular coherence tomography and scanning laser ophthalmoscopy. Targeted polymerase chain reaction (PCR) was performed as a first step to attempt to identify suspected mutations in C1QTNF5 and TIMP3 followed by whole genome sequencing.

Results: The three patients were noted to have symptoms of nyctalopia, early paracentral visual field loss and, in older patients, central vision loss. Imaging identified pseudodrusen, retinal atrophy and RPE-Bruch’s membrane separation. Whole genome sequencing of the proband revealed two novel heterozygous variants in C1QTNF5, c.556C>T, and c.569C>G. The mutation segregated with disease in this family, occurred in cis, and resulted in missense amino acid changes P186S and S190W in C1QTNF5. In silico modeling of the variants revealed that the S190W mutations was likely to have the greatest pathologic effect and that the combination of the mutations was likely to have an additive effect.

Conclusions: The novel mutations in C1QTNF5 identified here expand the genotypic spectrum of mutations causing late-onset retinal dystrophy.     

Novel compound heterozygous mutation in the POC1B gene underlie peripheral cone dystrophy in a Chinese family

Purpose: To describe the clinical characteristics of a Chinese family with peripheral cone dystrophy (PCD) and identify the gene mutations causing PCD.

Methods: The Chinese PCD pedigree underwent comprehensive ophthalmic examinations, including visual acuity, slit lamp examination, fundoscopy, visual field examination, autofluorescence, fluorescence fundus angiography and indocyanine green angiography, full-field electroretinograms, and spectral-domain optical coherence tomography. The targeted next-generation sequencing of COD or cone-rod dystrophy (CORD) genes was used to identify the causative mutation.

Result: The fundus characteristics of the Chinese patient were consistent with PCD. The novel compound heterozygous mutation, c.1354C>T and c.710A>G, in POC1B was identified in the patient, the mutations were segregated with the PCD phenotype in the family and were absent from ethnically matched control chromosomes. Prediction analysis demonstrated the novel missense mutation, POC1B c.710A>G, might be damaging.

Conclusions: PCD was a type of COD or CORD and the novel compound heterozygous mutation in POC1B was responsible for PCD phenotype in the family.     

Great clinical variability of Nance Horan syndrome due to deleterious NHS mutations in two unrelated Spanish families

ABSTRACT

Background: Nance-Horan syndrome (NHS) is an X-linked rare congenital disorder caused by mutations in the NHS gene. Clinical manifestations include congenital cataracts, facial and dental dysmorphism and, in some cases, intellectual disability. The aim of the present work was to identify the genetic cause of this disease in two unrelated Spanish NHS families and to determine the relative involvement of this gene in the pathogenesis.

Materials and methods: Four members of a two-generation family, three males and one female (Family 1), and seven members of a three-generation family, two males and five females (Family 2) were recruited and their index cases were screened for mutations in the NHS gene and 26 genes related with ocular congenital anomalies by NGS (Next Generation Sequencing).

Results: Two pathogenic variants were found in the NHS gene: a nonsense mutation (p.Arg373X) and a frameshift mutation (p.His669ProfsX5). These mutations were found in the two unrelated NHS families with different clinical manifestations.

Conclusions: In the present study, we identified two truncation mutations (one of them novel) in the NHS gene, associated with NHS. Given the wide clinical variability of this syndrome, NHS may be difficult to detect in individuals with subtle clinical manifestations or when congenital cataracts are the primary clinical manifestation which makes us suspect that it can be underdiagnosed. Combination of genetic studies and clinical examinations are essential for the clinical diagnosis optimization.     

Identification of a Novel LCA6 Mutation in an Emirati Family

ABSTRACT

Purpose: To determine the cause of Leber congenital amaurosis (LCA) in a consanguineous Emirati family.

Methods: The clinical diagnosis was made on the basis of medical history, ophthalmoscopy and standard ERG. The diagnosis was confirmed by molecular genetic analysis of known LCA genes by Next-Generation Sequencing (NGS). The latter was performed by Bioscientia Institut, Germany (as a clinical service for Latifa Hospital, Dubai).

Results: The next generation sequencing of known LCA genes revealed a homozygous 1bp-insertion c.2608_2609insA in exon 16 of the RPGRIP1 gene. This mutation, which was confirmed by conventional Sanger sequencing, leads to a frameshift, resulting in a premature stop codon (p.Leu870TyrfsX7) and subsequently in a degradation of the m-RNA or in a truncation of the RPGRIP1 protein. The segregation analysis of the identified mutation was performed for the parental samples. Both parents carry the frameshift mutation in a heterozygous state.

Conclusion: We report a novel RPGRIP1 mutation causing LCA in a consanguineous Emirati family. To the best of our knowledge, this alteration has not been described in the literature so far.