RESUMO
With a worldwide prevalence of 1 in 4,000, retinitis pigmentosa (RP) is the most common form of hereditary retinal degeneration. More than 30 genes and loci have been implicated in nonsyndromic autosomal-recessive (ar) RP. Genome-wide homozygosity mapping was conducted in one Dutch and one Israeli family affected by arRP. The families were found to share a 5.9 Mb homozygous region on chromosome 2p23.1-p23.3. A missense variant in one of the genes residing in this interval, C2ORF71, has recently been reported to be associated with RP. C2ORF71, encoding a putative protein of 1,288 amino acids, was found to be specifically expressed in human retina. Furthermore, RT-PCR analysis revealed that in the mouse eye, C2orf71 is expressed as early as embryonic day 14. Mutation analysis detected a 1 bp deletion (c.946 del; p.Asn237MetfsX5) segregating with RP in the Dutch family, whereas a nonsense mutation (c.556C > T; p.Gln186X) was identified in the Israeli family. Microsatellite-marker analysis in additional Israeli families revealed cosegregation of a C2ORF71-linked haplotype in one other family, in which a 13 bp deletion (c.2756_2768 del; p.Lys919ThrfsX) was identified. Clinically, patients with mutations in C2ORF71 show signs of typical RP; these signs include poor night vision and peripheral field loss, typical retinal bone-spicule-type pigment deposits, pale appearance of the optic disk, and markedly reduced or completely extinguished electroretinograms. In conclusion, truncating mutations in C2ORF71 were identified in three unrelated families, thereby confirming the involvement of this gene in the etiology of arRP.
Assuntos
Mutação , Proteínas/genética , Retina/metabolismo , Retinose Pigmentar/genética , Animais , Mapeamento Cromossômico , Análise Mutacional de DNA , Proteínas do Olho/genética , Haplótipos , Homozigoto , Humanos , Camundongos , Repetições de Microssatélites , Mutação de Sentido Incorreto , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
PURPOSE: To determine the genetic defect and to describe the clinical characteristics in patients with retinitis punctata albescens (RPA) and fundus albipunctatus (FAP). DESIGN: Case series/observational study. PARTICIPANTS: We included 13 patients affected by RPA or FAP. METHODS: Thirteen patients were collected from 8 families with a retinal dystrophy characterized by tiny, yellow-white dots on funduscopy, typical for FAP or RPA. All patients underwent full ophthalmologic examinations, including visual field assessment. Fundus photography, and electroretinography were performed in 12 patients, and optical coherence tomography and fundus autofluorescence were performed in 4 patients. DNA samples of all patients were screened for mutations in RLBP1 and for mutations in RDH5 in patients who did not carry mutations in RLBP1. DNA samples of 2 sibling pairs of nonconsanguineous families who carried mutations neither in RLBP1 nor in RDH5 were analyzed by genome-wide homozygosity mapping. Sequence analysis was performed of LRAT, a candidate gene in a shared homozygous region. MAIN OUTCOME MEASURES: We assessed DNA sequence variants, best-corrected visual acuity, fundus appearance, visual field measurements, electroretinogram responses, optical coherence tomography, and fundus autofluorescence. RESULTS: A homozygous frameshift mutation was identified in LRAT in 4 patients with RPA. Mutations in RLBP1 were identified in 7 patients with RPA and in 1 patient with FAP and cone dystrophy. One patient had compound heterozygous mutations in RDH5 and suffered from FAP with mild maculopathy. CONCLUSIONS: A genetic defect was identified in LRAT as a novel cause of RPA. LRAT is therefore the fourth gene involved in the visual cycle that may cause a white-dot retinopathy. We also revealed that mutations in RLBP1 may lead to FAP with cone dystrophy.
Assuntos
Aciltransferases/genética , Mutação da Fase de Leitura , Doenças Retinianas/genética , Adolescente , Adulto , Idoso , Oxirredutases do Álcool/genética , Proteínas de Transporte/genética , Criança , Análise Mutacional de DNA , Eletrorretinografia , Angiofluoresceinografia , Homozigoto , Humanos , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único , Retina/fisiopatologia , Doenças Retinianas/diagnóstico , Doenças Retinianas/fisiopatologia , Tomografia de Coerência Óptica , Acuidade Visual/fisiologia , Testes de Campo Visual , Campos Visuais/fisiologia , Adulto JovemRESUMO
In patients with autosomal-recessive retinitis pigmentosa (arRP), homozygosity mapping was performed for detection of regions harboring genes that might be causative for RP. In one affected sib pair, a shared homozygous region of 5.0 Mb was identified on chromosome 6, within the RP25 locus. One of the genes residing in this interval was the retina-expressed gene EGFL11. Several genes resembling EGFL11 were predicted just centromeric of EGFL11. Extensive long-range RT-PCR, combined with 5'- and 3'- RACE analysis, resulted in the identification of a 10-kb transcript, starting with the annotated exons of EGFL11 and spanning 44 exons and 2 Mb of genomic DNA. The transcript is predicted to encode a 3165-aa extracellular protein containing 28 EGF-like and five laminin A G-like domains. Interestingly, the second part of the protein was found to be the human ortholog of Drosophila eyes shut (eys), also known as spacemaker, a protein essential for photoreceptor morphology. Mutation analysis in the sib pair homozygous at RP25 revealed a nonsense mutation (p.Tyr3156X) segregating with RP. The same mutation was identified homozygously in three arRP siblings of an unrelated family. A frame-shift mutation (pPro2238ProfsX16) was found in an isolated RP patient. In conclusion, we identified a gene, coined eyes shut homolog (EYS), consisting of EGFL11 and the human ortholog of Drosophila eys, which is mutated in patients with arRP. With a size of 2 Mb, it is one of the largest human genes, and it is by far the largest retinal dystrophy gene. The discovery of EYS might shed light on a critical component of photoreceptor morphogenesis.
Assuntos
Proteínas de Drosophila/genética , Drosophila/genética , Proteínas do Olho/genética , Mutação , Retinose Pigmentar/genética , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Estudos de Casos e Controles , Mapeamento Cromossômico , Cromossomos Humanos Par 6 , Códon sem Sentido , Análise Mutacional de DNA , Eletrorretinografia , Éxons , Feminino , Mutação da Fase de Leitura , Genes Recessivos , Homozigoto , Humanos , Masculino , Dados de Sequência Molecular , Linhagem , Polimorfismo de Nucleotídeo Único , Estrutura Terciária de Proteína , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , IrmãosRESUMO
Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal dystrophies characterised ultimately by the loss of photoreceptor cells. We have recently identified a new gene(EYS) encoding an ortholog of Drosophila space maker (spam) as a commonly mutated gene in autosomal recessive RP. In the present study, we report the identification of 73 sequence variations in EYS, of which 28 are novel. Of these, 42.9% (12/28) are very likely pathogenic, 17.9% (5/28)are possibly pathogenic, whereas 39.3% (11/28) are SNPs. In addition, we have detected 3 pathogenic changes previously reported in other populations. We are also presenting the characterisation of EYS homologues in different species, and a detailed analysis of the EYS domains, with the identification of an interesting novel feature: a putative coiled-coil domain.Majority of the mutations in the arRP patients have been found within the domain structures of EYS. The minimum observed prevalence of distinct EYS mutations in our group of patients is of 15.9% (15/94), confirming a major involvement of EYS in the pathogenesis of arRP in the Spanish population. Along with the detection of three recurrent mutations in Caucasian population, our hypothesis of EYS being the first prevalent gene in arRP has been reinforced in the present study.
Assuntos
Proteínas do Olho/genética , Mutação , Retinose Pigmentar/genética , Sequência de Aminoácidos , Animais , Estudos de Casos e Controles , Análise Mutacional de DNA , Proteínas de Drosophila/genética , Evolução Molecular , Proteínas do Olho/química , Feminino , Genes Recessivos , Variação Genética , Humanos , Masculino , Dados de Sequência Molecular , Linhagem , Polimorfismo de Nucleotídeo Único , Estrutura Terciária de Proteína , Espanha , Homologia Estrutural de ProteínaRESUMO
OBJECTIVE: To determine the prevalence of mutations in the EYS gene in a cohort of patients affected by autosomal recessive retinitis pigmentosa (RP) and to describe the associated phenotype. DESIGN: Case series. PARTICIPANTS: Two hundred forty-five patients affected by autosomal recessive RP. METHODS: All coding exons of EYS were screened for mutations by polymerase chain reaction amplification and sequence analysis. All 12 patients carrying mutations in EYS were re-examined, which included Goldmann kinetic perimetry, electroretinography, and high-resolution spectral-domain optical coherence tomography (OCT). MAIN OUTCOME MEASURES: DNA sequence variants, best-corrected visual acuity, fundus appearance, visual field assessments using Goldmann kinetic perimetry, electroretinogram responses, and OCT images. RESULTS: Nine novel truncating mutations and one previously described mutation in EYS were identified in 11 families. In addition, 18 missense changes of uncertain pathogenicity were found. Patients carrying mutations in EYS demonstrated classic RP with night blindness as the initial symptom, followed by gradual constriction of the visual field and a decline of visual acuity later in life. The onset of symptoms typically occurred between the second and fourth decade of life. The fundus displayed bone spicules increasing in density with age and generalized atrophy of the retinal pigment epithelium and choriocapillaris with relative sparing of the posterior pole until later in the disease process, when atrophic macular changes occurred. CONCLUSIONS: Mutations in EYS account for approximately 5% of autosomal recessive RP patients in a cohort of patients consisting predominantly of patients of western European ancestry. The EYS-associated RP phenotype is typical and fairly homogeneous in most patients.
Assuntos
Proteínas do Olho/genética , Mutação , Retinose Pigmentar/genética , Adulto , Idoso , Sequência de Aminoácidos , Análise Mutacional de DNA , Eletrorretinografia , Feminino , Genes Recessivos , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Linhagem , Fenótipo , Reação em Cadeia da Polimerase , Prevalência , Retina/fisiologia , Retinose Pigmentar/fisiopatologia , Tomografia de Coerência Óptica , Acuidade Visual/fisiologia , Testes de Campo VisualRESUMO
The authors wish to make the following correction to this paper [1]. [...].
RESUMO
Enhanced S-cone syndrome (ESCS) is mainly associated with mutations in the NR2E3 gene. However, rare mutations in the NRL gene have been reported in patients with ESCS. We report on an ESCS phenotype in additional patients with autosomal recessive NRL (arNRL) mutations. Three Moroccan patients of two different families with arNRL mutations were enrolled in this study. The mutation in the DNA of one patient, from a consanguineous marriage, was detected by homozygosity mapping. The mutation in the DNA of two siblings from a second family was detected in a targeted next-generation sequencing project. Full ophthalmic examination was performed, including best-corrected visual acuity, slit-lamp biomicroscopy, funduscopy, Goldmann kinetic perimetry, optical coherence tomography, fundus autofluorescence, and extended electroretinography including an amber stimulus on a blue background and a blue stimulus on an amber background. One patient carried a homozygous missense mutation (c.508C>A; p.Arg170Ser) in the NRL gene, whereas the same mutation was identified heterozygously in the two siblings of a second family, in combination with a one base-pair deletion (c.654del; p.Cys219Valfs*4) on the other allele. All patients had reduced visual acuity and showed a typical clumped pigmentary retinal degeneration (CPRD). Foveal schisis-like changes were observed in the oldest patient. An electroretinogram (ERG) under dark-adapted conditions showed absent responses for low stimulus strengths and reduced responses for high stimulus strengths, with constant b-wave latencies despite increasing stimulus strength. A relatively high amplitude was detected with a blue stimulus on an amber background, while an amber stimulus on a blue background showed reduced responses. The arNRL mutations cause a phenotype with typical CPRD. This phenotype has previously been described in patients with ESCS caused by NR2E3 mutations, and rarely by NRL mutations. Based on our findings in ERG testing, we conclude that S-cone function is enhanced in our patients in a similar manner as in patients with NR2E3-associated ESCS, confirming previous reports of NRL as a second gene to cause ESCS.
RESUMO
OBJECTIVE: To investigate the involvement of the Bardet-Biedl syndrome (BBS) gene BBS1 p.M390R variant in nonsyndromic autosomal recessive retinitis pigmentosa (RP). METHODS: Homozygosity mapping of a patient with isolated RP was followed by BBS1 sequence analysis. We performed restriction fragment length polymorphism analysis of the p.M390R allele in 2007 patients with isolated RP or autosomal recessive RP and in 1824 ethnically matched controls. Patients with 2 BBS1 variants underwent extensive clinical and ophthalmologic assessment. RESULTS: In an RP proband who did not fulfill the clinical criteria for BBS, we identified a large homozygous region encompassing the BBS1 gene, which carried the p.M390R variant. In addition, this variant was detected homozygously in 10 RP patients and 1 control, compound heterozygously in 3 patients, and heterozygously in 5 patients and 6 controls. The 14 patients with 2 BBS1 variants showed the entire clinical spectrum, from nonsyndromic RP to full-blown BBS. In 8 of 14 patients, visual acuity was significantly reduced. In patients with electroretinographic responses, a rod-cone pattern of photoreceptor degeneration was observed. CONCLUSIONS: Variants in BBS1 are significantly associated with nonsyndromic autosomal recessive RP and relatively mild forms of BBS. As exemplified in this study by the identification of a homozygous p.M390R variant in a control individual and in unaffected parents of BBS patients in other studies, cis - or trans -acting modifiers may influence the disease phenotype. CLINICAL RELEVANCE: It is important to monitor patients with an early diagnosis of mild BBS phenotypes for possible life-threatening conditions.
Assuntos
Síndrome de Bardet-Biedl/genética , DNA/genética , Proteínas Associadas aos Microtúbulos/genética , Mutação de Sentido Incorreto , Retinose Pigmentar/genética , Adulto , Alelos , Síndrome de Bardet-Biedl/diagnóstico , Síndrome de Bardet-Biedl/etnologia , Canadá/epidemiologia , Análise Mutacional de DNA , Eletrorretinografia , Etnicidade , Europa (Continente)/epidemiologia , Feminino , Humanos , Israel/epidemiologia , Masculino , Microscopia Acústica , Proteínas Associadas aos Microtúbulos/metabolismo , Pessoa de Meia-Idade , Oftalmoscopia , Linhagem , Fenótipo , Prevalência , Retinose Pigmentar/diagnóstico , Retinose Pigmentar/etnologiaRESUMO
PURPOSE: To determine the genetic defects underlying autosomal recessive retinitis pigmentosa (arRP) in the Dutch population and in a subset of patients originating from other countries. The hypothesis was that, because there has been little migration over the past centuries in certain areas of The Netherlands, a significant fraction of Dutch arRP patients carry their genetic defect in the homozygous state. METHODS: High-resolution genome-wide SNP genotyping on SNP arrays and subsequent homozygosity mapping were performed in a large cohort of 186 mainly nonconsanguineous arRP families living in The Netherlands. Candidate genes residing in homozygous regions were sequenced. RESULTS: In ~94% of the affected individuals, large homozygous sequences were identified in their genome. In 42 probands, at least one of these homozygous regions contained one of the 26 known arRP genes. Sequence analysis of the corresponding genes in each of these patients revealed 21 mutations and two possible pathogenic changes, 14 of which were novel. All mutations were identified in only a single family, illustrating the genetic diversity within the Dutch population. CONCLUSIONS: This report demonstrates that homozygosity mapping is a powerful tool for identifying the genetic defect underlying genetically heterogeneous recessive disorders like RP, even in populations with little consanguinity.
Assuntos
Mapeamento Cromossômico , Estudo de Associação Genômica Ampla/métodos , Homozigoto , Mutação/genética , Polimorfismo de Nucleotídeo Único , Retinose Pigmentar/genética , Consanguinidade , Análise Mutacional de DNA , Genes Recessivos , Genótipo , Humanos , Análise em Microsséries , Países Baixos , Reação em Cadeia da PolimeraseRESUMO
PURPOSE: To characterize the role of EYS, a recently identified retinal disease gene, in families with inherited retinal degenerations in the Israeli and Palestinian populations. METHODS: Clinical and molecular analyses included family history, ocular examination, full-field electroretinography (ERG), perimetry, autozygosity mapping, mutation detection, and estimation of mutation age. RESULTS: Autozygosity mapping was performed in 171 consanguineous Israeli and Palestinian families with inherited retinal degenerations. Large homozygous regions, harboring the EYS gene, were identified in 15 of the families. EYS mutation analysis in the 15 index cases, followed by genotyping of specific mutations in an additional 121 cases of inherited retinal degenerations, revealed five novel null mutations, two of which are founder mutations, in 10 Israeli and Palestinian families with autosomal recessive retinitis pigmentosa (arRP). The most common mutation identified was a founder mutation in the Moroccan Jewish subpopulation. The ESTIAGE program produced an estimate that the age of the most recent common ancestor was 26 generations. The retinal phenotype in most patients was typical yet relatively severe RP, with an early age of onset and nonrecordable ERGs on presentation. CONCLUSIONS: The results demonstrate that EYS is currently the most commonly mutated arRP gene in the Israeli population, mainly due to founder mutations. EYS mutations were associated with an RP phenotype in all patients. The authors concluded that the gene plays only a minor role in causing other retinal phenotypes.
Assuntos
Árabes/genética , Proteínas do Olho/genética , Genes Recessivos , Judeus/genética , Retinose Pigmentar/etnologia , Retinose Pigmentar/genética , Adulto , Árabes/estatística & dados numéricos , Análise Mutacional de DNA , Eletrorretinografia , Feminino , Efeito Fundador , Haplótipos , Humanos , Israel/epidemiologia , Judeus/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Oftalmoscopia , Linhagem , Fenótipo , Retinose Pigmentar/patologia , Campos Visuais , Adulto JovemRESUMO
PURPOSE. To identify the genetic defect in a family with variable retinal phenotypes. The proband had a diagnosis of Leber congenital amaurosis (LCA), whereas her two cousins had an early-onset severe retinal dystrophy (EOSRD) with useful vision. A distant family member had retinitis pigmentosa (RP). METHODS. DNA samples of the affected family members were genotyped with 250 K genome-wide SNP microarrays. Genetic defects were localized by linkage analysis and homozygosity mapping, and candidate genes were analyzed by sequencing. Patients underwent a full ophthalmic examination. RESULTS. Compound heterozygous mutations in CEP290 were identified in the proband and her two cousins: the frequent c.2991+1655A>G founder mutation and a novel nonsense mutation in exon 7 (c.451C>T, p.Arg151X). The proband had nystagmus, hyperopia, a flat electroretinogram (ERG), and decreased visual acuity (20/250) from birth. The two cousins had minimal scotopic ERG responses at the age of 2. In one of these patients, visual acuity had reached a level of 20/32 at age 5, which is high for patients with CEP290 mutations. Analysis of the CEP290 mRNA in affected individuals revealed altered splice forms in which either exon 7 or exons 7 and 8 were skipped. In both mutant cDNA products, the open reading frame was not disrupted. Furthermore, homozygosity mapping and mutation analysis in the distant family member affected by RP revealed a homozygous mutation in MERTK, but no CEP290 mutations. This MERTK mutation was heterozygously present in the most severely affected (LCA) patient, but was absent in the two more mildly affected cousins. CONCLUSIONS. A novel nonsense mutation in CEP290 results in nonsense-associated altered splicing. That the remaining open reading frame is intact may explain the less severe phenotype observed in the two affected cousins. The additional heterozygous mutation in MERTK may clarify the more severe phenotype in the proband. This study extends the phenotypic spectrum of CEP290-associated diseases at the mild end.
Assuntos
Antígenos de Neoplasias/genética , Códon sem Sentido , Éxons/genética , Amaurose Congênita de Leber/genética , Proteínas de Neoplasias/genética , Degeneração Retiniana/genética , Sequência de Bases , Proteínas de Ciclo Celular , Criança , Mapeamento Cromossômico , Cromossomos Humanos Par 12/genética , Proteínas do Citoesqueleto , Análise Mutacional de DNA , Eletrorretinografia , Feminino , Genótipo , Humanos , Masculino , Dados de Sequência Molecular , Nistagmo Patológico/genética , Linhagem , Fenótipo , Polimorfismo de Nucleotídeo Único , Proteínas Proto-Oncogênicas/genética , RNA Mensageiro/metabolismo , Receptores Proteína Tirosina Quinases/genética , Acuidade Visual , c-Mer Tirosina QuinaseRESUMO
PURPOSE: To determine the genetic defect and to describe the clinical characteristics in a cohort of mainly nonconsanguineous cone-rod dystrophy (CRD) patients. METHODS: One hundred thirty-nine patients with diagnosed CRD were recruited. Ninety of them were screened for known mutations in ABCA4, and those carrying one or two mutations were excluded from further research. Genome-wide homozygosity mapping was performed in the remaining 108. Known genes associated with autosomal recessive retinal dystrophies located within a homozygous region were screened for mutations. Patients in whom a mutation was detected underwent further ophthalmic examination. RESULTS: Homozygous sequence variants were identified in eight CRD families, six of which were nonconsanguineous. The variants were detected in the following six genes: ABCA4, CABP4, CERKL, EYS, KCNV2, and PROM1. Patients carrying mutations in ABCA4, CERKL, and PROM1 had typical CRD symptoms, but a variety of retinal appearances on funduscopy, optical coherence tomography, and autofluorescence imaging. CONCLUSIONS: Homozygosity mapping led to the identification of new mutations in consanguineous and nonconsanguineous patients with retinal dystrophy. Detailed clinical characterization revealed a variety of retinal appearances, ranging from nearly normal to extensive retinal remodeling, retinal thinning, and debris accumulation. Although CRD was initially diagnosed in all patients, the molecular findings led to a reappraisal of the diagnosis in patients carrying mutations in EYS, CABP4, and KCNV2.
Assuntos
Mapeamento Cromossômico , Proteínas do Olho/genética , Homozigoto , Mutação , Células Fotorreceptoras de Vertebrados/patologia , Retinose Pigmentar/genética , Antígeno AC133 , Transportadores de Cassetes de Ligação de ATP/genética , Adolescente , Sequência de Aminoácidos , Antígenos CD/genética , Proteínas de Ligação ao Cálcio/genética , Criança , Consanguinidade , Análise Mutacional de DNA , Feminino , Angiofluoresceinografia , Glicoproteínas/genética , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Oftalmoscopia , Peptídeos/genética , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Retinose Pigmentar/diagnóstico , Tomografia de Coerência ÓpticaRESUMO
PURPOSE: The purpose of this study was to identify the causative gene defect in two siblings with an uncharacterized cone-rod dysfunction and to describe the clinical characteristics. METHODS: Genome-wide homozygosity mapping, with a 250K SNP-array followed by a search for candidate genes, was performed. The patients underwent ophthalmic examination, including elaborate electroretinography. RESULTS: In a Dutch sib pair, a shared 9-Mb homozygous region was found on 11q13.1-q13.5 that encompasses the CABP4 gene, previously implicated in autosomal recessive incomplete congenital stationary night blindness (CSNB2) in two small families. A novel homozygous p.Arg216X mutation in CABP4 was detected in the sib pair. Quantitative RT-PCR on RNA isolated from patient lymphoblast cells showed no nonsense-mediated degradation of mutant CABP4 mRNA. Clinically, patients presented with reduced visual acuity, photophobia, and abnormal color vision, but they did not experience night blindness. Electroretinograms showed electronegative mixed rod-cone responses and severely reduced cone responses, as in CSNB2. Isolated rod responses, however, were (sub)normal. CONCLUSIONS: A novel homozygous nonsense mutation in CABP4 in two siblings resulted in a phenotype with severely reduced cone function and only negligibly reduced rod function on electroretinography and psychophysical testing. Since these patients and two of three previously described patients do not experience night blindness, the name CSNB2 is confusing for patients as well as clinicians. Therefore, the authors propose to name the phenotype congenital cone-rod synaptic disorder.