Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Int J Mol Sci ; 23(4)2022 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-35216494

RESUMEN

The circadian clock, which drives a wide range of bodily rhythms in synchrony with the day-night cycle, is based on a molecular oscillator that ticks with a period of approximately 24 h. Timed proteasomal degradation of clock components is central to the fine-tuning of the oscillator's period. FBXL3 is a protein that functions as a substrate-recognition factor in the E3 ubiquitin ligase complex, and was originally shown in mice to mediate degradation of CRY proteins and thus contribute to the mammalian circadian clock mechanism. By exome sequencing, we have identified a FBXL3 mutation in patients with syndromic developmental delay accompanied by morphological abnormalities and intellectual disability, albeit with a normal sleep pattern. We have investigated the function of FBXL3 in the zebrafish, an excellent model to study both vertebrate development and circadian clock function and, like humans, a diurnal species. Loss of fbxl3a function in zebrafish led to disruption of circadian rhythms of promoter activity and mRNA expression as well as locomotor activity and sleep-wake cycles. However, unlike humans, no morphological effects were evident. These findings point to an evolutionary conserved role for FBXL3 in the circadian clock system across vertebrates and to the acquisition of developmental roles in humans.


Asunto(s)
Relojes Circadianos/genética , Proteínas F-Box/genética , Enfermedades Genéticas Congénitas/genética , Enfermedades Raras/genética , Pez Cebra/genética , Animales , Ritmo Circadiano/genética , Humanos , Discapacidad Intelectual/genética , Mamíferos/genética , Modelos Animales , Mutación/genética
2.
Mol Genet Metab ; 133(2): 222-229, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33972171

RESUMEN

BACKGROUND AND PURPOSE: Mitochondrial aminoacyl-tRNA synthetases-encoded by ARS2 genes-are evolutionarily conserved enzymes that catalyse the attachment of amino acids to their cognate tRNAs, ensuring the accuracy of the mitochondrial translation process. ARS2 gene mutations are associated with a wide range of clinical presentations affecting the CNS. METHODS: Two senior neuroradiologists analysed brain MRI of 25 patients (age range: 3 d-25 yrs.; 11 males; 14 females) with biallelic pathogenic variants of 11 ARS2 genes in a retrospective study conducted between 2002 and 2019. RESULTS: Though several combinations of brain MRI anomalies were highly suggestive of specific aetiologies (DARS2, EARS2, AARS2 and RARS2 mutations), our study detected no MRI pattern common to all patients. Stroke-like lesions were associated with pathogenic SARS2 and FARS2 variants. We also report early onset cerebellar atrophy and calcifications in AARS2 mutations, early white matter involvement in RARS2 mutations, and absent involvement of thalami in EARS2 mutations. Finally, our findings show that normal brain MRI results do not exclude the presence of ARS2 mutations: 5 patients with normal MRI images were carriers of pathogenic IARS2, YARS2, and FARS2 variants. CONCLUSION: Our study extends the spectrum of brain MRI anomalies associated with pathogenic ARS2 variants and suggests ARS2 mutations are largely underdiagnosed.


Asunto(s)
Alanina-ARNt Ligasa/genética , Arginino-ARNt Ligasa/genética , Aspartato-ARNt Ligasa/genética , Encéfalo/diagnóstico por imagen , Proteínas Mitocondriales/genética , Fenilalanina-ARNt Ligasa/genética , Adolescente , Adulto , Aminoacil-ARNt Sintetasas/clasificación , Aminoacil-ARNt Sintetasas/genética , Encéfalo/patología , Niño , Preescolar , Femenino , Variación Genética , Humanos , Lactante , Recién Nacido , Imagen por Resonancia Magnética , Masculino , Mutación/genética , Fenotipo , Adulto Joven
3.
J Hum Genet ; 66(8): 835-840, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-33612823

RESUMEN

MSTO1 is a cytoplasmic protein that modulates mitochondrial dynamics by promoting mitochondrial fusion. Mutations in the MSTO1 gene are responsible for an extremely rare condition characterized by early-onset myopathy and cerebellar ataxia. We report here two siblings from a large Ashkenazi Jewish family, presenting with a progressive neuromuscular disease characterized by ataxia and myopathy. By whole exome sequencing, we found a novel homozygous missense mutation (c.1403T>A, p.Leu468Gln) in MSTO1. Studies performed on fibroblasts from the index patient demonstrated the pathogenic role of the identified variant; we found that MSTO1 protein level was reduced and that mitochondrial network was fragmented or formed enlarged structures. Moreover, patient's cells showed reduced mitochondrial DNA amount. Our report confirms that MSTO1 mutations are typically recessive, and associated with clinical phenotypes characterized by early-onset muscle impairment and ataxia, often with upper motor neuron signs and varied cognitive impairment.


Asunto(s)
Ataxia/genética , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Proteínas del Citoesqueleto/genética , Proteínas del Citoesqueleto/metabolismo , ADN Mitocondrial/metabolismo , Mitocondrias/genética , Mitocondrias/metabolismo , Enfermedades Musculares/genética , Adulto , Femenino , Fibroblastos/metabolismo , Homocigoto , Humanos , Judíos/genética , Mutación Missense , Linaje , Fenotipo , Hermanos , Secuenciación del Exoma , Adulto Joven
4.
Am J Hum Genet ; 101(5): 716-724, 2017 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-29100085

RESUMEN

DHX30 is a member of the family of DExH-box helicases, which use ATP hydrolysis to unwind RNA secondary structures. Here we identified six different de novo missense mutations in DHX30 in twelve unrelated individuals affected by global developmental delay (GDD), intellectual disability (ID), severe speech impairment and gait abnormalities. While four mutations are recurrent, two are unique with one affecting the codon of one recurrent mutation. All amino acid changes are located within highly conserved helicase motifs and were found to either impair ATPase activity or RNA recognition in different in vitro assays. Moreover, protein variants exhibit an increased propensity to trigger stress granule (SG) formation resulting in global translation inhibition. Thus, our findings highlight the prominent role of translation control in development and function of the central nervous system and also provide molecular insight into how DHX30 dysfunction might cause a neurodevelopmental disorder.


Asunto(s)
Discapacidades del Desarrollo/genética , Mutación Missense/genética , ARN Helicasas/genética , Adenosina Trifosfatasas/genética , Adolescente , Aminoácidos/genética , Línea Celular , Línea Celular Tumoral , Sistema Nervioso Central/patología , Niño , Preescolar , Femenino , Células HEK293 , Humanos , Discapacidad Intelectual/genética , Masculino , ARN/genética
5.
J Autoimmun ; 112: 102462, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32561150

RESUMEN

Nodding Syndrome (NS) is a fatal pediatric epilepsy of unknown etiology, accompanied by multiple neurological impairments, and associated with Onchocerca volvulus (Ov), malnutrition, war-induced trauma, and other insults. NS patients have neuroinflammation, and ~50% have cross-reactive Ov/Leiomodin-1 neurotoxic autoimmune antibodies. RESULTS: Studying 30 South Sudanese NS patients and a similar number of healthy subjects from the same geographical region, revealed autoimmune antibodies to 3 extracellular peptides of ionotropic glutamate receptors in NS patients: AMPA-GluR3B peptide antibodies (86%), NMDA-NR1 peptide antibodies (77%) and NMDA-NR2 peptide antibodies (87%) (in either 1:10, 1:100 or 1:1000 serum dilution). In contrast, NS patients did not have 26 other well-known autoantibodies that target the nervous system in several autoimmune-mediated neurological diseases. We demonstrated high expression of both AMPA-GluR3 and NMDA-NR1 in human neural cells, and also in normal human CD3+ T cells of both helper CD4+ and cytotoxic CD8+ types. Patient's GluR3B peptide antibodies were affinity-purified, and by themselves precipitated short 70 kDa neuronal GluR3. NS patient's affinity-purified GluR3B peptide antibodies also bound to, induced Reactive Oxygen Species (ROS) in, and killed both human neural cells and T cells within 1-2 hours only. NS patient's purified IgGs, or serum (1:10 or 1:30), induced similar effects. In vivo video EEG experiments in normal mice, revealed that when NS patient's purified IgGs were released continuously (24/7 for 1 week) in normal mouse brain, they induced all the following: 1.Seizures, 2. Cerebellar Purkinje cell loss, 3. Degeneration in the hippocampus and cerebral cortex, and 4. Elevation of CD3+ T cells, and of activated Mac-2+microglia and GFAP+astrocytes in both the gray and white matter of the cerebral cortex, hippocampus, corpus calossum and cerebellum of mice. NS patient's serum cytokines: IL-1ß, IL-2, IL-6, IL-8, TNFα, IFNγ, are reduced by 85-99% compared to healthy subjects, suggesting severe immunodeficiency in NS patients. This suspected immunodeficiency could be caused by combined effects of the: 1. Chronic Ov infection, 2. Malnutrition, 3. Killing of NS patient's T cells by patient's own GluR3B peptide autoimmune antibodies (alike the killing of normal human T cells by the NS patient's GluR3B peptide antibodies found herein in vitro). CONCLUSIONS: Regardless of NS etiology, NS patients suffer from 'Dual-targeted Autoimmune Sword': autoimmune AMPA GluR3B peptide antibodies that bind, induce ROS in, and kill both neural cells and T cells. These neurotoxic and immunotoxic GluR3B peptide autoimmune antibodies, and also NS patient's NMDA-NR1/NR2A and Ov/Leiomodin-1 autoimmune antibodies, must be silenced or removed. Moreover, the findings of this study are relevant not only to NS, but also to many more patients with other types of epilepsy, which have GluR3B peptide antibodies in serum and/or CSF. This claim is based on the following facts: 1. The GluR3 subunit is expressed in neural cells in crucial brains regions, in motor neurons in the spinal cord, and also in other cells in the body, among them T cells of the immune system, 2. The GluR3 subunit has diverse neurophysiological role, and its deletion or abnormal function can: disrupt oscillatory networks of both sleep and breathing, impair motor coordination and exploratory activity, and increase the susceptibility to generate seizures, 3. GluR3B peptide antibodies were found so far in ~27% of >300 epilepsy patients worldwide, which suffer from various other types of severe, intractable and enigmatic epilepsy, and which turned out to be 'Autoimmune Epilepsy'. Furthermore, the findings of this study could be relevant to different neurological diseases besides epilepsy, since other neurotransmitter-receptors autoantibodies are present in other neurological and psychiatric diseases, e.g. autoimmune antibodies against other GluRs, Dopamine receptors, GABA receptors, Acetylcholine receptors and others. These neurotransmitter-receptors autoimmune autoantibodies might also act as 'Dual-targeted Autoimmune Sword' and damage both neural cells and T cells (as the AMPA-GluR3B peptide antibodies induced in the present study), since T cells, alike neural cells, express most if not all these neurotransmitter receptors, and respond functionally to the respective neurotransmitters - a scientific and clinical topic we coined 'Nerve-Driven Immunity'.


Asunto(s)
Autoanticuerpos/inmunología , Autoantígenos/inmunología , Síndrome del Cabeceo/inmunología , Especies Reactivas de Oxígeno/metabolismo , Receptores AMPA/inmunología , Adolescente , Adulto , Autoanticuerpos/sangre , Autoanticuerpos/aislamiento & purificación , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Voluntarios Sanos , Humanos , Inmunoglobulina G , Masculino , Neuroinmunomodulación/inmunología , Neuronas/inmunología , Neuronas/patología , Síndrome del Cabeceo/sangre , Síndrome del Cabeceo/patología , Linfocitos T/inmunología , Linfocitos T/patología , Adulto Joven
6.
Am J Hum Genet ; 98(4): 782-8, 2016 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-27040691

RESUMEN

Through an international multi-center collaboration, 13 individuals from nine unrelated families and affected by likely pathogenic biallelic variants in TBC1-domain-containing kinase (TBCK) were identified through whole-exome sequencing. All affected individuals were found to share a core phenotype of intellectual disability and hypotonia, and many had seizures and showed brain atrophy and white-matter changes on neuroimaging. Minor non-specific facial dysmorphism was also noted in some individuals, including multiple older children who developed coarse features similar to those of storage disorders. TBCK has been shown to regulate the mammalian target of rapamycin (mTOR) signaling pathway, which is also stimulated by exogenous leucine supplementation. TBCK was absent in cells from affected individuals, and decreased phosphorylation of phospho-ribosomal protein S6 was also observed, a finding suggestive of downregulation of mTOR signaling. Lastly, we demonstrated that activation of the mTOR pathway in response to L-leucine supplementation was retained, suggesting a possible avenue for directed therapies for this condition.


Asunto(s)
Discapacidad Intelectual/genética , Hipotonía Muscular/genética , Mutación , Proteínas Serina-Treonina Quinasas/genética , Alelos , Niño , Preescolar , Femenino , Variación Genética , Humanos , Discapacidad Intelectual/diagnóstico , Masculino , Hipotonía Muscular/diagnóstico , Grupos Raciales/genética , Transducción de Señal , Serina-Treonina Quinasas TOR/genética , Serina-Treonina Quinasas TOR/metabolismo
7.
Neurogenetics ; 19(4): 227-235, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-30043326

RESUMEN

The major facilitator superfamily domain-containing protein 2A (MFSD2A) is a constituent of the blood-brain barrier and functions to transport lysophosphatidylcholines (LPCs) into the central nervous system. LPCs such as that derived from docosahexanoic acid (DHA) are indispensable to neurogenesis and maintenance of neurons, yet cannot be synthesized within the brain and are dependent on MFSD2A for brain uptake. Recent studies have implicated MFSD2A mutations in lethal and non-lethal microcephaly syndromes, with the severity correlating to the residual activity of the transporter. We describe two siblings with shared parental ancestry, in whom we identified a homozygous missense mutation (c.1205C > A; p.Pro402His) in MFSD2A. Both affected individuals had microcephaly, hypotonia, appendicular spasticity, dystonia, strabismus, and global developmental delay. Neuroimaging revealed paucity of white matter with enlarged lateral ventricles. Plasma lysophosphatidylcholine (LPC) levels were elevated, reflecting reduced brain transport. Cell-based studies of the p.Pro402His mutant protein indicated complete loss of activity of the transporter despite the non-lethal, attenuated phenotype. The aggregate data of MFSD2A-associated genotypes and phenotypes suggest that additional factors, such as nutritional supplementation or modifying genetic factors, may modulate the severity of disease and call for consideration of treatment options for affected individuals.


Asunto(s)
Enfermedades Desmielinizantes/genética , Ácidos Docosahexaenoicos/metabolismo , Microcefalia/genética , Mutación Missense , Proteínas Supresoras de Tumor/genética , Sustitución de Aminoácidos , Animales , Transporte Biológico/genética , Barrera Hematoencefálica/metabolismo , Niño , Preescolar , Enfermedades Desmielinizantes/metabolismo , Discapacidades del Desarrollo/genética , Femenino , Células HEK293 , Homocigoto , Humanos , Metabolismo de los Lípidos/genética , Lisofosfatidilcolinas/metabolismo , Masculino , Ratones , Ratones Noqueados , Microcefalia/metabolismo , Modelos Moleculares , Vaina de Mielina/metabolismo , Linaje , Hermanos , Simportadores , Proteínas Supresoras de Tumor/química , Proteínas Supresoras de Tumor/metabolismo
8.
Hum Mol Genet ; 25(14): 2985-2996, 2016 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-27193168

RESUMEN

The exosome complex is the most important RNA processing machinery within the cell. Mutations in its subunits EXOSC8 and EXOSC3 cause pontocerebellar hypoplasia, spinal muscular atrophy (SMA) and central nervous system demyelination. We present a patient with SMA-like phenotype carrying a homozygous mutation in RBM7-a subunit of the nuclear exosome targeting (NEXT) complex-which is known to bind and carry specific subtypes of coding and non-coding RNAs to the exosome. The NEXT complex with other protein complexes is responsible for the substrate specificity of the exosome. We performed RNA-sequencing (RNA-seq) analysis on primary fibroblasts of patients with mutations in EXOSC8 and RBM7 and gene knock-down experiments using zebrafish as a model system. RNA-seq analysis identified significantly altered expression of 62 transcripts shared by the two patient cell lines. Knock-down of rbm7, exosc8 and exosc3 in zebrafish showed a common pattern of defects in motor neurons and cerebellum. Our data indicate that impaired RNA metabolism may underlie the clinical phenotype by fine tuning gene expression which is essential for correct neuronal differentiation.


Asunto(s)
Complejo Multienzimático de Ribonucleasas del Exosoma/genética , Atrofia Muscular Espinal/genética , Proteínas de Unión al ARN/genética , Animales , Cerebelo/metabolismo , Cerebelo/patología , Modelos Animales de Enfermedad , Exosomas/genética , Humanos , Neuronas Motoras/metabolismo , Neuronas Motoras/patología , Atrofia Muscular Espinal/metabolismo , Atrofia Muscular Espinal/patología , Mutación , Análisis de Secuencia de ARN , Pez Cebra/metabolismo
9.
Hum Mol Genet ; 25(21): 4635-4648, 2016 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-28158450

RESUMEN

Mutation in a growing spectrum of genes is known to either cause or contribute to primary or secondary microcephaly. In primary microcephaly the genetic determinants frequently involve mutations that contribute to or modulate the microtubule cytoskeleton by causing perturbations of neuronal proliferation and migration. Here we describe four patients from two unrelated families each with an infantile neurodegenerative disorder characterized by loss of developmental milestones at 9­24 months of age followed by seizures, dystonia and acquired microcephaly. The patients harboured homozygous missense mutations (A475T and A586V) in TBCD, a gene encoding one of five tubulin-specific chaperones (termed TBCA-E) that function in concert as a nanomachine required for the de novo assembly of the α/ß tubulin heterodimer. The latter is the subunit from which microtubule polymers are assembled. We found a reduced intracellular abundance of TBCD in patient fibroblasts to about 10% (in the case of A475T) or 40% (in the case of A586V) compared to age-matched wild type controls. Functional analyses of the mutant proteins revealed a partially compromised ability to participate in the heterodimer assembly pathway. We show via in utero shRNA-mediated suppression that a balanced supply of tbcd is critical for cortical cell proliferation and radial migration in the developing mouse brain. We conclude that TBCD is a novel functional contributor to the mammalian cerebral cortex development, and that the pathological mechanism resulting from the mutations we describe is likely to involve compromised interactions with one or more TBCD-interacting effectors that influence the dynamics and behaviour of the neuronal cytoskeleton.


Asunto(s)
Trastornos Heredodegenerativos del Sistema Nervioso/genética , Microcefalia/genética , Proteínas Asociadas a Microtúbulos/genética , Animales , Encéfalo/metabolismo , Citoesqueleto/metabolismo , Fibroblastos/metabolismo , Trastornos Heredodegenerativos del Sistema Nervioso/metabolismo , Humanos , Lactante , Recién Nacido , Ratones , Ratones Endogámicos C57BL/embriología , Proteínas Asociadas a Microtúbulos/metabolismo , Microtúbulos/genética , Microtúbulos/fisiología , Tubulina (Proteína)/genética , Tubulina (Proteína)/metabolismo , Secuenciación del Exoma/métodos
11.
J Med Genet ; 52(11): 749-53, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26307567

RESUMEN

BACKGROUND: The genetic heterogeneity of developmental delay and cognitive impairment is vast. The endocytic network is essential for neural development and synaptic plasticity by regulating the sorting of numerous transmembrane proteins. Disruption of the pathway can lead to neuronal pathology. Endosomal biogenesis relies on two Rab proteins, Rab5 and Rab7, which bind to two hexameric tethering complexes, the endosomal class C core vacuole/endosome tethering complex (CORVET) and the late endosomal/lysosomal homotypic fusion and protein sorting complex (HOPS). Both complexes consist of four core proteins and differ by their specific Rab-binding proteins. OBJECTIVES: To identify the molecular basis of a neurological disease, which consists of global developmental stagnation at 3-8 months, increasing appendicular spasticity, truncal hypotonia and acquired microcephaly, with variable seizure disorder, accompanied by thin corpus callosum, paucity of white matter and delayed myelination in eight patients from four unrelated Ashkenazi-Jewish (AJ) families. METHODS: Exome analysis, homozygosity mapping and Mup1-GFP transport assay in mutant yeast. RESULTS: Homozygosity for a missense mutation, p.Cys846Gly, in one of the endosomal biogenesis core proteins, VPS11, was identified in all the patients. This was shown to be a founder mutation with a carrier frequency of 0.6% in the AJ population. The homologous yeast mutant had moderate impairment of fusion of the late endosome to the vacuole in Mup1-GFP transport assay. CONCLUSIONS: We speculate that in neuronal cells, impairment of fusion of the late endosome to the vacuole would attenuate the degradation of plasma membrane receptors, thereby underlying the progressive neuronal phenotype in our patients. The VPS11 p.Cys846Gly mutation should be added to the AJ carrier screening panel.


Asunto(s)
Anomalías Múltiples/genética , Discapacidades del Desarrollo/genética , Mutación Missense , Vaina de Mielina/metabolismo , Proteínas de Transporte Vesicular/genética , Anomalías Múltiples/metabolismo , Adolescente , Niño , Análisis Mutacional de ADN , Discapacidades del Desarrollo/metabolismo , Endosomas/genética , Endosomas/metabolismo , Femenino , Humanos , Lactante , Judíos/genética , Masculino , Microcefalia/genética , Microcefalia/metabolismo , Hipotonía Muscular/genética , Hipotonía Muscular/metabolismo , Vaina de Mielina/genética , Vaina de Mielina/patología , Linaje , Saccharomyces cerevisiae , Síndrome , Adulto Joven
12.
Am J Hum Genet ; 90(3): 518-23, 2012 Mar 09.
Artículo en Inglés | MEDLINE | ID: mdl-22405087

RESUMEN

Degeneration of the cerebrum, cerebellum, and retina in infancy is part of the clinical spectrum of lysosomal storage disorders, mitochondrial respiratory chain defects, carbohydrate glycosylation defects, and infantile neuroaxonal dystrophy. We studied eight individuals from two unrelated families who presented at 2-6 months of age with truncal hypotonia and athetosis, seizure disorder, and ophthalmologic abnormalities. Their course was characterized by failure to acquire developmental milestones and culminated in profound psychomotor retardation and progressive visual loss, including optic nerve and retinal atrophy. Despite their debilitating state, the disease was compatible with survival of up to 18 years. Laboratory investigations were normal, but the oxidation of glutamate by muscle mitochondria was slightly reduced. Serial brain MRI displayed progressive, prominent cerebellar atrophy accompanied by thinning of the corpus callosum, dysmyelination, and frontal and temporal cortical atrophy. Homozygosity mapping followed by whole-exome sequencing disclosed a Ser112Arg mutation in ACO2, encoding mitochondrial aconitase, a component of the Krebs cycle. Specific aconitase activity in the individuals' lymphoblasts was severely reduced. Under restrictive conditions, the mutant human ACO2 failed to complement a yeast ACO1 deletion strain, whereas the wild-type human ACO2 succeeded, indicating that this mutation is pathogenic. Thus, a defect in mitochondrial aconitase is associated with an infantile neurodegenerative disorder affecting mainly the cerebellum and retina. In the absence of noninvasive biomarkers, determination of the ACO2 sequence or of aconitase activity in lymphoblasts are warranted in similarly affected individuals, based on clinical and neuroradiologic grounds.


Asunto(s)
Aconitato Hidratasa/genética , Cerebelo/anomalías , Mitocondrias/enzimología , Mutación , Enfermedades Neurodegenerativas/genética , Retina/anomalías , Adolescente , Atrofia/enzimología , Atrofia/genética , Cerebelo/enzimología , Niño , Preescolar , Exoma , Exones , Femenino , Genotipo , Ácido Glutámico/metabolismo , Heterocigoto , Homocigoto , Humanos , Lactante , Imagen por Resonancia Magnética/métodos , Masculino , Mitocondrias/genética , Enfermedades Neurodegenerativas/enzimología , Oxidación-Reducción , Polimorfismo de Nucleótido Simple , Retina/enzimología
13.
Brain ; 137(Pt 4): 1030-8, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24566669

RESUMEN

Congenital disorders of glycosylation comprise a group of genetic defects with a high frequency of intellectual disability, caused by deficient glycosylation of proteins and lipids. The molecular basis of the majority of the congenital disorders of glycosylation type I subtypes, localized in the cytosol and endoplasmic reticulum, has been solved. However, elucidation of causative genes for defective Golgi glycosylation (congenital disorders of glycosylation type II) remains challenging because of a lack of sufficiently specific diagnostic serum methods. In a single patient with intellectual disability, whole-exome sequencing revealed MAN1B1 as congenital disorder of glycosylation type II candidate gene. A novel mass spectrometry method was applied for high-resolution glycoprofiling of intact plasma transferrin. A highly characteristic glycosylation signature was observed with hybrid type N-glycans, in agreement with deficient mannosidase activity. The speed and robustness of the method allowed subsequent screening in a cohort of 100 patients with congenital disorder of glycosylation type II, which revealed the characteristic glycosylation profile of MAN1B1-congenital disorder of glycosylation in 11 additional patients. Abnormal hybrid type N-glycans were also observed in the glycoprofiles of total serum proteins, of enriched immunoglobulins and of alpha1-antitrypsin in variable amounts. Sanger sequencing revealed MAN1B1 mutations in all patients, including severe truncating mutations and amino acid substitutions in the alpha-mannosidase catalytic site. Clinically, this group of patients was characterized by intellectual disability and delayed motor and speech development. In addition, variable dysmorphic features were noted, with truncal obesity and macrocephaly in ∼65% of patients. In summary, MAN1B1 deficiency appeared to be a frequent cause in our cohort of patients with unsolved congenital disorder of glycosylation type II. Our method for analysis of intact transferrin provides a rapid test to detect MAN1B1-deficient patients within congenital disorder of glycosylation type II cohorts and can be used as efficient diagnostic method to identify MAN1B1-deficient patients in intellectual disability cohorts. In addition, it provides a functional confirmation of MAN1B1 mutations as identified by next-generation sequencing in individuals with intellectual disability.


Asunto(s)
Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/genética , Proteínas de la Membrana/deficiencia , Proteínas de la Membrana/genética , Proteínas Nucleares/deficiencia , Proteínas Nucleares/genética , Adolescente , Adulto , Preescolar , Análisis Mutacional de ADN/métodos , Proteínas de Unión al ADN , Femenino , Glicosilación , Humanos , Lactante , Discapacidad Intelectual/sangre , Masculino , Proteínas de la Membrana/sangre , Mutación , Proteínas Nucleares/sangre , Adulto Joven
14.
J Inherit Metab Dis ; 35(1): 125-31, 2012 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-21607760

RESUMEN

Defects of the mitochondrial oxidative phosphorylation (OXPHOS) system are frequent causes of neurological disorders in children. Linkage analysis and DNA sequencing identified a new founder p.G250V substitution in the C20ORF7 complex I chaperone in five Ashkenazi Jewish patients from two families with a combined OXPHOS complex I and IV defect presenting with Leigh's syndrome in infancy. Complementation with the wild type gene restored complex I, but only partially complex IV activity. Although the pathogenic mechanism remains elusive, a C20ORF7 defect should be considered not only in isolated complex I deficiency, but also in combination with decreased complex IV. Given the significant 1:290 carrier rate for the p.G250V mutation among Ashkenazi Jews, this mutation should be screened in all Ashkenazi patients with Leigh's syndrome prior to muscle biopsy.


Asunto(s)
Complejo IV de Transporte de Electrones/genética , Complejo I de Transporte de Electrón/genética , Metiltransferasas/genética , Enfermedades Mitocondriales/genética , Proteínas Mitocondriales/genética , Fosforilación Oxidativa , Biopsia , Niño , Preescolar , Salud de la Familia , Femenino , Prueba de Complementación Genética , Humanos , Judíos , Enfermedad de Leigh/genética , Masculino , Modelos Genéticos , Músculos/patología
15.
Hum Mutat ; 32(11): 1259-67, 2011 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-21786365

RESUMEN

Choline acetyltransferase (ChAT; EC 2.3.1.6) catalyzes synthesis of acetylcholine from acetyl-CoA (AcCoA) and choline in cholinergic neurons. Mutations in CHAT cause potentially lethal congenital myasthenic syndromes associated with episodic apnea (ChAT-CMS). Here, we analyze the functional consequences of 12 missense and one nonsense mutations of CHAT in 11 patients. Nine of the mutations are novel. We examine expression of the recombinant missense mutants in Bosc 23 cells, determine their kinetic properties and thermal stability, and interpret the functional effects of 11 mutations in the context of the atomic structural model of human ChAT. Five mutations (p.Trp421Ser, p.Ser498Pro, p.Thr553Asn, p.Ala557Thr, and p.Ser572Trp) reduce enzyme expression to less than 50% of wild-type. Mutations with severe kinetic effects are located in the active-site tunnel (p.Met202Arg, p.Thr553Asn, and p.Ala557Thr) or adjacent to the substrate binding site (p.Ser572Trp), or exert their effect allosterically (p.Trp421Ser and p.Ile689Ser). Two mutations with milder kinetic effects (p.Val136Met and p.Ala235Thr) are also predicted to act allosterically. One mutation (p.Thr608Asn) below the nucleotide binding site of CoA enhances dissociation of AcCoA from the enzyme-substrate complex. Two mutations introducing a proline residue into an α-helix (p.Ser498Pro and p.Ser704Pro) impair the thermal stability of ChAT.


Asunto(s)
Colina O-Acetiltransferasa/genética , Mutación , Sitios de Unión , Colina O-Acetiltransferasa/química , Colina O-Acetiltransferasa/metabolismo , Neuronas Colinérgicas/enzimología , Neuronas Colinérgicas/metabolismo , Estudios de Asociación Genética , Humanos , Cinética , Síndromes Miasténicos Congénitos/genética , Conformación Proteica , Relación Estructura-Actividad
16.
PLoS Negl Trop Dis ; 15(10): e0009821, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34662363

RESUMEN

Nodding syndrome (NS) is a catastrophic and enigmatic childhood epilepsy, accompanied by multiple neurological impairments and neuroinflammation. Of all the infectious, environmental and psychological factors associated with NS, the major culprit is Onchocerca Volvulus (Ov)-a parasitic worm transmitted to human by blackflies. NS seems to be an 'Autoimmune Epilepsy' in light of the recent findings of deleterious autoimmune antibodies to Glutamate receptors and to Leiomodin-I in NS patients. Moreover, we recently found immunogenetic fingerprints in HLA peptide-binding grooves associate with protection or susceptibility to NS. Macrophage migration inhibitory factor (MIF) is an immune-regulatory cytokine playing a central role in modulating innate and adaptive immunity. MIF is also involved in various pathologies: infectious, autoimmune and neurodegenerative diseases, epilepsy and others. Herein, two functional polymorphisms in the MIF gene, a -794 CATT5-8 microsatellite repeat and a -173 G/C single-nucleotide polymorphism, were assessed in 49 NS patients and 51 healthy controls from South Sudan. We also measured MIF plasma levels in established NS patients and healthy controls. We discovered that the frequency of the high-expression MIF -173C containing genotype was significantly lower in NS patients compared to healthy controls. Interestingly however, MIF plasma levels were significantly elevated in NS patients than in healthy controls. We further demonstrated that the HLA protective and susceptibility associations are dominant over the MIF association with NS. Our findings suggest that MIF might have a dual role in NS. Genetically controlled high-expression MIF genotype is associated with disease protection. However, elevated MIF in the plasma may contribute to the detrimental autoimmunity, neuroinflammation and epilepsy.


Asunto(s)
Factores Inhibidores de la Migración de Macrófagos/genética , Síndrome del Cabeceo/genética , Adolescente , Adulto , Animales , Niño , Preescolar , Femenino , Genotipo , Humanos , Factores Inhibidores de la Migración de Macrófagos/sangre , Masculino , Repeticiones de Microsatélite , Síndrome del Cabeceo/sangre , Síndrome del Cabeceo/parasitología , Onchocerca volvulus/fisiología , Polimorfismo de Nucleótido Simple , Adulto Joven
17.
PLoS Negl Trop Dis ; 14(7): e0008436, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32639997

RESUMEN

Nodding syndrome (NS) is a devastating and enigmatic childhood epilepsy. NS is accompanied by multiple neurological impairments and neuroinflammation, and associated with the parasite Onchocerca volvulus (Ov) and other environmental factors. Moreover, NS seems to be an 'Autoimmune Epilepsy' since: 1. ~50% of NS patients have neurotoxic cross-reactive Ov/Leimodin-I autoimmune antibodies. 2. Our recently published findings: Most (~86%) of NS patients have glutamate-receptor AMPA-GluR3B peptide autoimmune antibodies that bind, induce Reactive Oxygen Species, and kill both neural cells and T cells. Furthermore, NS patient's IgG induce seizures, brain multiple damage alike occurring in brains of NS patients, and elevation of T cells and activated microglia and astrocytes, in brains of normal mice. Human Leukocyte antigen (HLA) class I and II molecules are critical for initiating effective beneficial immunity against foreign microorganisms and contributing to proper brain function, but also predispose to detrimental autoimmunity against self-peptides. We analyzed seven HLA loci, either by next-generation-sequencing or Sequence-Specific-Oligonucleotide-Probe, in 48 NS patients and 51 healthy controls from South Sudan. We discovered that NS associates significantly with both protective HLA haplotype: HLA-B*42:01, C*17:01, DRB1*03:02, DQB1*04:02 and DQA1*04:01, and susceptible motif: Ala24, Glu63 and Phe67, in the HLA-B peptide-binding groove. These amino acids create a hydrophobic and sterically closed peptide-binding HLA pocket, favoring proline residue. Our findings suggest that immunogenetic fingerprints in HLA peptide-binding grooves tentatively associate with protection or susceptibility to NS. Accordingly, different HLA molecules may explain why under similar environmental factors, only some children, within the same families, tribes and districts, develop NS, while others do not.


Asunto(s)
Antígenos HLA/química , Antígenos HLA/inmunología , Síndrome del Cabeceo/inmunología , Adolescente , Adulto , Secuencias de Aminoácidos , Autoanticuerpos/inmunología , Estudios de Casos y Controles , Niño , Preescolar , Susceptibilidad a Enfermedades , Femenino , Antígenos HLA/genética , Humanos , Masculino , Síndrome del Cabeceo/genética , Síndrome del Cabeceo/prevención & control , Receptores AMPA/genética , Receptores AMPA/inmunología , Sudán del Sur , Adulto Joven
18.
Eur J Hum Genet ; 27(9): 1419-1426, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-30976113

RESUMEN

The ATP/GTP-Binding Protein 1 (AGTPBP1) gene (OMIM *606830) catalyzes deglutamylation of polyglutamylated proteins, and its deficiency manifests by cerebellar ataxia and peripheral neuropathy in mice and lower motor neuron-like disease in sheep. In the mutant mice, cerebellar atrophy due to Purkinje cell degeneration is observed, likely due to increased tubulin polyglutamylation in affected brain areas. We report two unrelated individuals who presented with early onset cerebellar atrophy, developmental arrest with progressive muscle weakness, and feeding and respiratory difficulties, accompanied by severe motor neuronopathy. Whole exome sequencing followed by segregation analysis in the families and cDNA studies revealed deleterious biallelic variants in the AGTPBP1 gene. We conclude that complete loss-of-function of AGTPBP1 in humans, just like in mice and sheep, is associated with cerebellar and motor neuron disease, reminiscent of Pontocerebellar Hypoplasia Type 1 (PCH1).


Asunto(s)
Alelos , Proteínas de Unión al GTP/genética , Enfermedad de la Neurona Motora/etiología , Enfermedad de la Neurona Motora/metabolismo , Mutación , D-Ala-D-Ala Carboxipeptidasa de Tipo Serina/genética , Degeneraciones Espinocerebelosas/etiología , Degeneraciones Espinocerebelosas/metabolismo , Tubulina (Proteína)/metabolismo , Sustitución de Aminoácidos , Preescolar , Consanguinidad , Análisis Mutacional de ADN , Femenino , Humanos , Lactante , Imagen por Resonancia Magnética , Masculino , Enfermedad de la Neurona Motora/diagnóstico por imagen , Enfermedad de la Neurona Motora/patología , Enfermedades Neurodegenerativas/diagnóstico por imagen , Enfermedades Neurodegenerativas/etiología , Enfermedades Neurodegenerativas/metabolismo , Enfermedades Neurodegenerativas/patología , Degeneraciones Espinocerebelosas/diagnóstico por imagen , Degeneraciones Espinocerebelosas/patología , Secuenciación del Exoma
19.
Eur J Paediatr Neurol ; 20(1): 69-79, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26542466

RESUMEN

BACKGROUND: TECPR2 was first described as a disease causing gene when the c.3416delT frameshift mutation was found in five Jewish Bukharian patients with similar features. It was suggested to constitute a new subtype of complex hereditary spastic paraparesis (SPG49). RESULTS: We report here 3 additional patients from unrelated non-Bukharian families, harboring two novel mutations (c.1319delT, c.C566T) in this gene. Accumulating clinical data clarifies that in addition to intellectual disability and evolving spasticity the main disabling feature of this unique disorder is autonomic-sensory neuropathy accompanied by chronic respiratory disease and paroxysmal autonomic events. CONCLUSION: We suggest that the disease should therefore be classified as a new subtype of hereditary sensory-autonomic neuropathy. The discovery of additional mutations in non-Bukharian patients implies that this disease might be more common than previously appreciated and should therefore be considered in undiagnosed cases of intellectual disability with autonomic features and respiratory symptoms regardless of demographic origin.


Asunto(s)
Proteínas Portadoras/genética , Disautonomía Familiar/genética , Neuropatías Hereditarias Sensoriales y Autónomas/genética , Discapacidad Intelectual/genética , Proteínas del Tejido Nervioso/genética , Paraplejía Espástica Hereditaria/genética , Proteínas Portadoras/química , Preescolar , Biología Computacional , ADN/genética , Electrodiagnóstico , Exoma , Mutación del Sistema de Lectura/genética , Neuropatías Hereditarias Sensoriales y Autónomas/psicología , Humanos , Lactante , Recién Nacido , Discapacidad Intelectual/psicología , Judíos , Masculino , Modelos Moleculares , Proteínas del Tejido Nervioso/química , Examen Neurológico , Linaje , Trastornos Respiratorios/etiología , Trastornos Respiratorios/genética , Paraplejía Espástica Hereditaria/psicología
20.
Early Hum Dev ; 71(1): 19-28, 2003 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-12614947

RESUMEN

BACKGROUND: Vitamin A is an essential micronutrient for the development and growth of the fetus. The objective of this study was to identify a possible association between low serum retinol and birth weight in healthy mother-infant pairs in Southern Israel. A secondary objective was to examine ethnic differences in maternal and cord serum retinol. METHODS: Serum retinol was measured at delivery from pairs of healthy mothers and healthy mature newborns. RESULTS: Of the 313 mother-infant pairs studied, 56% were Jews and 44% Bedouins. The proportion of infants with birth weight of 2500-2999 g was greater among mothers with lower serum retinol (<0.7 micromol/l) compared to mothers with normal serum retinol (> or =0.7 micromol/l) (p<0.001). Cord retinol <0.7 micromol/l was more frequent in infants with birth weight 2500-2990 g compared to infants with birth weight > or =3000 g (p=0.006). Using a split model and stepwise multiple regression analysis, infant's birth weight was significantly influenced by cord retinol concentration in infants born to mothers with low serum retinol; gestational age and cord retinol alone explained 27% of the variability of birth weight in this group. A higher proportion of Bedouin than Jewish infants had serum retinol <0.7 and <0.35 micromol/l (both p<0.001). CONCLUSION: Low cord and maternal serum retinol may reflect poor vitamin A status of the newborn and the mother, which in turn may affect fetal growth.


Asunto(s)
Árabes , Peso al Nacer , Sangre Fetal/química , Judíos , Embarazo/sangre , Vitamina A/sangre , Adulto , Arabia/etnología , Estudios Transversales , Femenino , Edad Gestacional , Humanos , Israel/epidemiología , Deficiencia de Vitamina A/sangre , Deficiencia de Vitamina A/complicaciones , Deficiencia de Vitamina A/etnología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA