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1.
Genes (Basel) ; 10(5)2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31091803

RESUMO

Mutations in CEP290 encoding a centrosomal protein important to cilia formation cause a spectrum of diseases, from isolated retinal dystrophies to multivisceral and sometimes embryo-lethal ciliopathies. In recent years, endogenous and/or selective non-canonical exon skipping of mutant exons have been documented in attenuated retinal disease cases. This observation led us to consider targeted exon skipping to bypass protein truncation resulting from a recurrent mutation in exon 36 (c.4723A > T, p.Lys1575*) causing isolated retinal ciliopathy. Here, we report two unrelated individuals (P1 and P2), carrying the mutation in homozygosity but affected with early-onset severe retinal dystrophy and congenital blindness, respectively. Studying skin-derived fibroblasts, we observed basal skipping and nonsense associated-altered splicing of exon 36, producing low (P1) and very low (P2) levels of CEP290 products. Consistent with a more severe disease, fibroblasts from P2 exhibited reduced ciliation compared to P1 cells displaying normally abundant cilia; both lines presented however significantly elongated cilia, suggesting altered axonemal trafficking. Antisense oligonucleotides (AONs)-mediated skipping of exon 36 increased the abundance of the premature termination codon (PTC)-free mRNA and protein, reduced axonemal length and improved cilia formation in P2 but not in P1 expressing higher levels of skipped mRNA, questioning AON-mediated exon skipping to treat patients carrying the recurrent c.4723A > T mutation.

2.
Hum Mol Genet ; 2018 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-29771326

RESUMO

CEP290 mutations cause a spectrum of ciliopathies from Leber congenital amaurosis type 10 (LCA10) to embryo-lethal Meckel syndrome (MKS). Using panel-based molecular diagnosis testing for inherited retinal diseases, we identified two individuals with some preserved vision despite biallelism for presumably truncating CEP290 mutations. The first one carried a homozygous 1 base-pair deletion in exon 17, introducing a premature termination codon (PTC) in exon 18 (c.1666del; p.Ile556Phefs*17). mRNA analysis revealed a basal exon skipping (BES) of exon 18, providing mutant cells with the ability to escape protein truncation, while disrupting the reading frame in controls. The second individual harbored compound heterozygous nonsense mutations in exon 8 (c.508A>T, p.Lys170*) and exon 32 (c.4090G>T, p.Glu1364*), respectively. Some CEP290 lacking exon 8 were detected in mutant fibroblasts but not in controls whereas some skipping of exon 32 occurred in both lines, but with higher amplitude in the mutant. Considering that the deletion of either exon maintains the reading frame in either line, skipping in mutant cells likely involves nonsense-associated altered splicing (NAS) alone (exon 8), or with BES (exon 32). Skipping of PTC-containing exons in mutant cells allowed production of CEP290 isoforms with preserved ability to assemble into a high molecular weight complex and to interact efficiently with proteins important for cilia formation and intraflagellar trafficking. In contrast, studying LCA10 and MKS fibroblasts we show moderate to severe cilia alterations, providing support for a correlation between disease severity and the ability of cells to express shortened, yet functional, CEP290 isoforms.

3.
Am J Hum Genet ; 101(6): 1006-1012, 2017 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-29198720

RESUMO

Leber congenital amaurosis (LCA) is a neurodegenerative disease of photoreceptor cells that causes blindness within the first year of life. It occasionally occurs in syndromic metabolic diseases and plurisystemic ciliopathies. Using exome sequencing in a multiplex family and three simplex case subjects with an atypical association of LCA with early-onset hearing loss, we identified two heterozygous mutations affecting Arg391 in ß-tubulin 4B isotype-encoding (TUBB4B). Inspection of the atomic structure of the microtubule (MT) protofilament reveals that the ß-tubulin Arg391 residue contributes to a binding pocket that interacts with α-tubulin contained in the longitudinally adjacent αß-heterodimer, consistent with a role in maintaining MT stability. Functional analysis in cultured cells overexpressing FLAG-tagged wild-type or mutant TUBB4B as well as in primary skin-derived fibroblasts showed that the mutant TUBB4B is able to fold, form αß-heterodimers, and co-assemble into the endogenous MT lattice. However, the dynamics of growing MTs were consistently altered, showing that the mutations have a significant dampening impact on normal MT growth. Our findings provide a link between sensorineural disease and anomalies in MT behavior and describe a syndromic LCA unrelated to ciliary dysfunction.


Assuntos
Amaurose Congênita de Leber/genética , Microtúbulos/genética , Tubulina (Proteína)/genética , Adulto , Sítios de Ligação/genética , Células Cultivadas , Criança , Análise Mutacional de DNA , Feminino , Humanos , Masculino , Microtúbulos/metabolismo , Pessoa de Meia-Idade , Mutação de Sentido Incorreto/genética , Células Fotorreceptoras/metabolismo , Tubulina (Proteína)/metabolismo , Sequenciamento Completo do Exoma
4.
J Med Genet ; 54(5): 346-356, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28031252

RESUMO

BACKGROUND: Non-syndromic hereditary optic neuropathy (HON) has been ascribed to mutations in mitochondrial fusion/fission dynamics genes, nuclear and mitochondrial DNA-encoded respiratory enzyme genes or nuclear genes of poorly known mitochondrial function. However, the disease causing gene remains unknown in many families. The objective of the present study was to identify the molecular cause of non-syndromic LHON-like disease in siblings born to non-consanguineous parents of French origin. METHODS: We used a combination of genetic analysis (gene mapping and whole-exome sequencing) in a multiplex family of non-syndromic HON and of functional analyses in patient-derived cultured skin fibroblasts and the yeast Yarrowia lipolytica. RESULTS: We identified compound heterozygote NDUFS2 disease-causing mutations (p.Tyr53Cys; p.Tyr308Cys). Studies using patient-derived cultured skin fibroblasts revealed mildly decreased NDUFS2 and complex I abundance but apparently normal respiratory chain activity. In the yeast Y. lipolytica ortholog NUCM, the mutations resulted in absence of complex I and moderate reduction in nicotinamide adenine dinucleotide-ubiquinone oxidoreductase activity, respectively. CONCLUSIONS: Biallelism for NDUFS2 mutations causing severe complex I deficiency has been previously reported to cause Leigh syndrome with optic neuropathy. Our results are consistent with the view that compound heterozygosity for severe and hypomorphic NDUFS2 mutations can cause non-syndromic HON. This observation suggests a direct correlation between the severity of NDUFS2 mutations and that of the disease and further support that there exist a genetic overlap between non-syndromic and syndromic HON due to defective mitochondrial function.


Assuntos
Mutação/genética , NADH Desidrogenase/genética , Atrofia Óptica Hereditária de Leber/genética , Adulto , Sequência de Aminoácidos , Animais , Sequência de Bases , Estudos de Casos e Controles , Bovinos , Sequência Conservada/genética , Complexo I de Transporte de Elétrons/química , Complexo I de Transporte de Elétrons/genética , Feminino , Fibroblastos/metabolismo , Haplótipos/genética , Heterozigoto , Humanos , Masculino , Mitocôndrias/genética , Proteínas Mutantes/metabolismo , NADH Desidrogenase/química , Oftalmoscopia , Linhagem , Fenótipo , Tomografia de Coerência Óptica , Yarrowia/metabolismo
6.
Adv Exp Med Biol ; 854: 517-24, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26427454

RESUMO

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 . Antisense oligonucleotide (AON)-mediated splice modulation appears to be a powerful approach to correct the consequences of such mutations at the pre-mRNA level , as demonstrated by promising results in clinical trials for several inherited disorders like Duchenne muscular dystrophy, hypercholesterolemia and various types of cancer. In this mini-review, we summarize ongoing pre-clinical research on AON-based therapy for a few genetic subtypes of IRD , speculate on other potential therapeutic targets, and discuss the opportunities and challenges that lie ahead to translate splice modulation therapy for retinal disorders to the clinic.


Assuntos
Oligonucleotídeos Antissenso/genética , Distrofias Retinianas/genética , Distrofias Retinianas/terapia , Reparo Gênico Alvo-Dirigido/métodos , Animais , Modelos Animais de Doenças , Predisposição Genética para Doença/genética , Humanos , Mutação , Precursores de RNA/genética , Processamento de RNA/genética
7.
Mol Ther Nucleic Acids ; 4: e250, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-26325627

RESUMO

Leber congenital amaurosis is a severe hereditary retinal dystrophy responsible for neonatal blindness. The most common disease-causing mutation (c.2991+1655A>G; 10-15%) creates a strong splice donor site that leads to insertion of a cryptic exon encoding a premature stop codon. Recently, we reported that splice-switching oligonucleotides (SSO) allow skipping of the mutant cryptic exon and the restoration of ciliation in fibroblasts of affected patients, supporting the feasibility of a SSO-mediated exon skipping strategy to correct the aberrant splicing. Here, we present data in the wild-type mouse, which demonstrate that intravitreal administration of 2'-OMePS-SSO allows selective alteration of Cep290 splicing in retinal cells, including photoreceptors as shown by successful alteration of Abca4 splicing using the same approach. We show that both SSOs and Cep290 skipped mRNA were detectable for at least 1 month and that intravitreal administration of oligonucleotides did not provoke any serious adverse event. These data suggest that intravitreal injections of SSO should be considered to bypass protein truncation resulting from the c.2991+1655A>G mutation as well as other truncating mutations in genes which like CEP290 or ABCA4 have a mRNA size that exceed cargo capacities of US Food and Drug Administration (FDA)-approved adeno-associated virus (AAV)-vectors, thus hampering gene augmentation therapy.

8.
J Med Genet ; 52(10): 657-65, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26275418

RESUMO

BACKGROUND: Bidirectional intraflagellar transport (IFT) consists of two major protein complexes, IFT-A and IFT-B. In contrast to the IFT-B complex, all components of IFT-A have recently been linked to human ciliopathies when defective. We therefore hypothesised that mutations in additional IFT-B encoding genes can be found in patients with multisystemic ciliopathies. METHODS: We screened 1628 individuals with reno-ocular ciliopathies by targeted next-generation sequencing of ciliary candidate genes, including all IFT-B encoding genes. RESULTS: Consequently, we identified a homozygous mutation in IFT81 affecting an obligatory donor splice site in an individual with nephronophthisis and polydactyly. Further, we detected a loss-of-stop mutation with extension of the deduced protein by 10 amino acids in an individual with neuronal ceroid lipofuscinosis-1. This proband presented with retinal dystrophy and brain lesions including cerebellar atrophy, a phenotype to which the IFT81 variant might contribute. Cultured fibroblasts of this latter affected individual showed a significant decrease in ciliated cell abundance compared with controls and increased expression of the transcription factor GLI2 suggesting deranged sonic hedgehog signalling. CONCLUSIONS: This work describes identification of mutations of IFT81 in individuals with symptoms consistent with the clinical spectrum of ciliopathies. It might represent the rare case of a core IFT-B complex protein found associated with human disease. Our data further suggest that defects in the IFT-B core are an exceedingly rare finding, probably due to its indispensable role for ciliary assembly in development.


Assuntos
Cílios/genética , Cílios/patologia , Olho/patologia , Rim/patologia , Proteínas Musculares/genética , Humanos , Mutação , Análise de Sequência de DNA
9.
Sci Transl Med ; 7(291): 291fs24, 2015 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-26062843

RESUMO

The total amount of functional mutant protein produced by cells underpins disease pleiotropy in the ciliopathies.


Assuntos
Doença/genética , Éxons/genética , Pleiotropia Genética , Predisposição Genética para Doença/genética , Modelos Genéticos , Humanos
10.
J Med Genet ; 51(12): 834-8, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25351951

RESUMO

BACKGROUND: Inherited optic neuropathy has been ascribed to mutations in mitochondrial fusion/fission dynamics genes, nuclear and mitochondrial DNA-encoded respiratory enzyme genes or nuclear genes of poorly known mitochondrial function. However, the disease causing gene remains unknown in many families. METHODS: We used exome sequencing in order to identify the gene responsible for isolated or syndromic optic atrophy in five patients from three independent families. RESULTS: We found homozygous or compound heterozygous missense and frameshift mutations in the gene encoding mitochondrial aconitase (ACO2), a tricarboxylic acid cycle enzyme, catalysing interconversion of citrate into isocitrate. Unlike wild type ACO2, all mutant ACO2 proteins failed to complement the respiratory growth of a yeast aco1-deletion strain. Retrospective studies using patient-derived cultured skin fibroblasts revealed various degrees of deficiency in ACO2 activity, but also in ACO1 cytosolic activity. CONCLUSIONS: Our study shows that autosomal recessive ACO2 mutations can cause either isolated or syndromic optic neuropathy. This observation identifies ACO2 as the second gene responsible for non-syndromic autosomal recessive optic neuropathies and provides evidence for a genetic overlap between isolated and syndromic forms, giving further support to the view that optic atrophy is a hallmark of defective mitochondrial energy supply.


Assuntos
Aconitato Hidratase/genética , Mutação , Doenças do Nervo Óptico/genética , Aconitato Hidratase/metabolismo , Adulto , Encéfalo/patologia , Pré-Escolar , Ciclo do Ácido Cítrico , Ativação Enzimática , Exoma , Evolução Fatal , Feminino , Expressão Gênica , Genes Recessivos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Imagem por Ressonância Magnética , Masculino , Oftalmoscópios , Atrofia Óptica/diagnóstico , Atrofia Óptica/genética , Doenças do Nervo Óptico/diagnóstico , Doenças do Nervo Óptico/metabolismo , Avaliação de Resultados da Assistência ao Paciente , Irmãos
11.
Am J Hum Genet ; 94(6): 891-7, 2014 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-24814191

RESUMO

Epileptic encephalopathies are increasingly thought to be of genetic origin, although the exact etiology remains uncertain in many cases. We describe here three girls from two nonconsanguineous families affected by a clinical entity characterized by dysmorphic features, early-onset intractable epilepsy, intellectual disability, and cortical blindness. In individuals from each family, brain imaging also showed specific changes, including an abnormally marked pontobulbar sulcus and abnormal signals (T2 hyperintensities) and atrophy in the occipital lobe. Exome sequencing performed in the first family did not reveal any gene with rare homozygous variants shared by both affected siblings. It did, however, show one gene, DOCK7, with two rare heterozygous variants (c.2510delA [p.Asp837Alafs(∗)48] and c.3709C>T [p.Arg1237(∗)]) found in both affected sisters. Exome sequencing performed in the proband of the second family also showed the presence of two rare heterozygous variants (c.983C>G [p.Ser328(∗)] and c.6232G>T [p.Glu2078(∗)]) in DOCK7. Sanger sequencing confirmed that all three individuals are compound heterozygotes for these truncating mutations in DOCK7. These mutations have not been observed in public SNP databases and are predicted to abolish domains critical for DOCK7 function. DOCK7 codes for a Rac guanine nucleotide exchange factor that has been implicated in the genesis and polarization of newborn pyramidal neurons and in the morphological differentiation of GABAergic interneurons in the developing cortex. All together, these observations suggest that loss of DOCK7 function causes a syndromic form of epileptic encephalopathy by affecting multiple neuronal processes.


Assuntos
Cegueira Cortical/genética , Epilepsia/genética , Proteínas Ativadoras de GTPase/genética , Deficiência Intelectual/genética , Criança , Pré-Escolar , Epilepsias Mioclônicas/genética , Exoma , Feminino , Proteínas Ativadoras de GTPase/metabolismo , Genes Recessivos , Fatores de Troca do Nucleotídeo Guanina/genética , Heterozigoto , Homozigoto , Humanos , Lactente , Masculino , Mutação , Linhagem , Fenótipo , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA , Espasmos Infantis/genética
12.
Am J Hum Genet ; 92(2): 265-70, 2013 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-23312594

RESUMO

Anophthalmia and microphthalmia (A/M) are early-eye-development anomalies resulting in absent or small ocular globes, respectively. A/M anomalies occur in syndromic or nonsyndromic forms. They are genetically heterogeneous, some mutations in some genes being responsible for both anophthalmia and microphthalmia. Using a combination of homozygosity mapping, exome sequencing, and Sanger sequencing, we identified homozygosity for one splice-site and two missense mutations in the gene encoding the A3 isoform of the aldehyde dehydrogenase 1 (ALDH1A3) in three consanguineous families segregating A/M with occasional orbital cystic, neurological, and cardiac anomalies. ALDH1A3 is a key enzyme in the formation of a retinoic acid gradient along the dorso-ventral axis during early eye development. Transitory expression of mutant ALDH1A3 open reading frames showed that both missense mutations reduce the accumulation of the enzyme, potentially leading to altered retinoic acid synthesis. Although the role of retinoic acid signaling in eye development is well established, our findings provide genetic evidence of a direct link between retinoic-acid-synthesis dysfunction and early-eye-development anomalies in humans.


Assuntos
Aldeído Desidrogenase/genética , Anoftalmia/enzimologia , Anoftalmia/genética , Genes Recessivos/genética , Microftalmia/enzimologia , Microftalmia/genética , Mutação/genética , Aldeído Oxirredutases , Segregação de Cromossomos/genética , Éxons/genética , Feminino , Ligação Genética , Células HEK293 , Homozigoto , Humanos , Íntrons/genética , Masculino , Proteínas Mutantes/metabolismo , Linhagem , Análise de Sequência de DNA
13.
Mol Ther Nucleic Acids ; 1: e29, 2012 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-23344081

RESUMO

Leber congenital amaurosis (LCA) is a severe hereditary retinal dystrophy responsible for congenital or early-onset blindness. The most common disease-causing mutation (>10%) is located deep in intron 26 of the CEP290 gene (c.2991+1655A>G). It creates a strong splice donor site that leads to insertion of a cryptic exon encoding a premature stop codon. In the present study, we show that the use of antisense oligonucleotides (AONs) allow an efficient skipping of the mutant cryptic exon and the restoration of ciliation in fibroblasts of affected patients. These data support the feasibility of an AON-mediated exon skipping strategy to correct the aberrant splicing.

14.
Hum Mutat ; 31(3): E1241-50, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20104588

RESUMO

Leber congenital amaurosis (LCA) is the earliest and most severe retinal degeneration. It may present as a congenital stationary cone-rod dystrophy (LCA type I) or a progressive yet severe rod-cone dystrophy (LCA type II). Twelve LCA genes have been identified, three of which account for Type I and nine for LCA type II. All proteins encoded by these genes but two are preferentially expressed in the retina and are responsible for non-syndromic LCA only. By contrast LCA5 and CEP290 are widely expressed and mutations in this latter result in a variety of phenotypes from non-syndromic retinal degeneration to pleiotropic disorders including senior-Loken (SNLS) and Joubert syndromes (JBTS). Recently, mutations in the widely expressed gene SPATA7 were reported to cause LCA or juvenile retinitis pigmentosa. The purpose of this study was i) to determine the level of expression of two major alternative SPATA7 transcripts in a large range of tissues and ii) to assess the involvement of this novel gene in a large cohort of unrelated patients affected with LCA (n = 134). Here, we report high SPATA7expression levels in retina, brain and testis with differential expression of the two transcripts. SPATA7 mutations were identified in few families segregating non-syndromic LCA (n = 4/134). Six different mutations were identified, four of which are novel; All affected both SPATA7 transcripts. The clinical evaluation of patients suggested that SPATA7 mutations account for the rod-cone dystrophy type of the disease.


Assuntos
Proteínas de Ligação a DNA/genética , Amaurose Congênita de Leber/genética , Adulto , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Masculino , Mutação , Fenótipo , Retina/patologia , Retinite Pigmentosa/genética , Síndrome
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