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1.
Cell ; 172(5): 952-965.e18, 2018 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-29474921

RESUMO

Viruses that are typically benign sometimes invade the brainstem in otherwise healthy children. We report bi-allelic DBR1 mutations in unrelated patients from different ethnicities, each of whom had brainstem infection due to herpes simplex virus 1 (HSV1), influenza virus, or norovirus. DBR1 encodes the only known RNA lariat debranching enzyme. We show that DBR1 expression is ubiquitous, but strongest in the spinal cord and brainstem. We also show that all DBR1 mutant alleles are severely hypomorphic, in terms of expression and function. The fibroblasts of DBR1-mutated patients contain higher RNA lariat levels than control cells, this difference becoming even more marked during HSV1 infection. Finally, we show that the patients' fibroblasts are highly susceptible to HSV1. RNA lariat accumulation and viral susceptibility are rescued by wild-type DBR1. Autosomal recessive, partial DBR1 deficiency underlies viral infection of the brainstem in humans through the disruption of tissue-specific and cell-intrinsic immunity to viruses.


Assuntos
Encefalopatias Metabólicas Congênitas/genética , Tronco Encefálico/metabolismo , Tronco Encefálico/virologia , RNA/química , RNA/metabolismo , Alelos , Sequência de Aminoácidos , Animais , Encefalopatias Metabólicas Congênitas/patologia , Tronco Encefálico/patologia , Encefalite Viral/genética , Escherichia coli/metabolismo , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Fibroblastos/virologia , Herpesvirus Humano 1 , Humanos , Interferons/metabolismo , Íntrons/genética , Masculino , Camundongos , Proteínas Mutantes/metabolismo , Mutação/genética , Fases de Leitura Aberta/genética , Linhagem , RNA Nucleotidiltransferases/química , RNA Nucleotidiltransferases/deficiência , RNA Nucleotidiltransferases/genética , Receptor 3 Toll-Like/metabolismo , Replicação Viral
2.
Hum Mol Genet ; 31(24): 4121-4130, 2022 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-35913762

RESUMO

The high-affinity copper transporter CTR1 is encoded by CTR1 (SLC31A1), a gene locus for which no detailed genotype-phenotype correlations have previously been reported. We describe identical twin male infants homozygous for a novel missense variant NM_001859.4:c.284 G > A (p.Arg95His) in CTR1 with a distinctive autosomal recessive syndrome of infantile seizures and neurodegeneration, consistent with profound central nervous system copper deficiency. We used clinical, biochemical and molecular methods to delineate the first recognized examples of human CTR1 deficiency. These included clinical phenotyping, brain imaging, assays for copper, cytochrome c oxidase (CCO), and mitochondrial respiration, western blotting, cell transfection experiments, confocal and electron microscopy, protein structure modeling and fetal brain and cerebral organoid CTR1 transcriptome analyses. Comparison with two other critical mediators of cellular copper homeostasis, ATP7A and ATP7B, genes associated with Menkes disease and Wilson disease, respectively, revealed that expression of CTR1 was highest. Transcriptome analyses identified excitatory neurons and radial glia as brain cell types particularly enriched for copper transporter transcripts. We also assessed the effects of Copper Histidinate in the patients' cultured cells and in the patients, under a formal clinical protocol. Treatment normalized CCO activity and enhanced mitochondrial respiration in vitro, and was associated with modest clinical improvements. In combination with present and prior studies, these infants' clinical, biochemical and molecular phenotypes establish the impact of this novel variant on copper metabolism and cellular homeostasis and illuminate a crucial role for CTR1 in human brain development. CTR1 deficiency represents a newly defined inherited disorder of brain copper metabolism.


Assuntos
Transportador de Cobre 1 , Cobre , Doenças Neurodegenerativas , Convulsões , Humanos , Masculino , Cobre/metabolismo , Transportador de Cobre 1/genética , Gêmeos , Lactente , Mutação de Sentido Incorreto , Síndrome , Doenças Neurodegenerativas/diagnóstico , Doenças Neurodegenerativas/genética , Convulsões/diagnóstico , Convulsões/genética
3.
J Inherit Metab Dis ; 2024 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-39318119

RESUMO

Newborn screening (NBS) for isovaleric acidemia (IVA) reduces mortality and morbidity; however, it has also resulted in the detection of individuals with an asymptomatic or mild presentation for which early detection via newborn screening has not been proven to alter neurological outcome. We reevaluated biochemical and molecular data for newborns flagged positive for IVA in aim of developing a new screening algorithm to exclude the latter from positive screening. Among 2 794 365 newborns underwent routine newborn screening in Israel, 412 flagged positive for IVA, of which, 371 were false positives on recall sample testing and 41 positive newborns were referred to the clinic. 38/41 have biochemical and molecular confirmation in keeping with IVA. Among the 38 patients, 32% (12/38) were classified as symptomatic while, 68% (26/38) were classified as asymptomatic. 69% of the latter group harbor the known variant associated with mild potentially asymptomatic phenotype, c.932C>T; p. Ala311Val. Among asymptomatic patients, only 46% (12/26) are currently treated. Two novel variants have been detected in the IVD gene: c.487G>A; p. Ala163Thr and c.985A>G; p. Met329Val. Cut-off recalculation, of referred newborns' initial biochemical results, after classifying the referred patients to two binary groups of symptomatic and asymptomatic, resulted in an improved NBS algorithm comprising of C5 >5 µM and C5/C2>0.2 and C5/C3>4 flagging only those likely to have the classic symptomatic phenotype.

4.
J Med Genet ; 60(11): 1133-1141, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37460201

RESUMO

BACKGROUND: SUMOylation involves the attachment of small ubiquitin-like modifier (SUMO) proteins to specific lysine residues on thousands of substrates with target-specific effects on protein function. Sentrin-specific proteases (SENPs) are proteins involved in the maturation and deconjugation of SUMO. Specifically, SENP7 is responsible for processing polySUMO chains on targeted substrates including the heterochromatin protein 1α (HP1α). METHODS: We performed exome sequencing and segregation studies in a family with several infants presenting with an unidentified syndrome. RNA and protein expression studies were performed in fibroblasts available from one subject. RESULTS: We identified a kindred with four affected subjects presenting with a spectrum of findings including congenital arthrogryposis, no achievement of developmental milestones, early respiratory failure, neutropenia and recurrent infections. All died within four months after birth. Exome sequencing identified a homozygous stop gain variant in SENP7 c.1474C>T; p.(Gln492*) as the probable aetiology. The proband's fibroblasts demonstrated decreased mRNA expression. Protein expression studies showed significant protein dysregulation in total cell lysates and in the chromatin fraction. We found that HP1α levels as well as different histones and H3K9me3 were reduced in patient fibroblasts. These results support previous studies showing interaction between SENP7 and HP1α, and suggest loss of SENP7 leads to reduced heterochromatin condensation and subsequent aberrant gene expression. CONCLUSION: Our results suggest a critical role for SENP7 in nervous system development, haematopoiesis and immune function in humans.

5.
J Inherit Metab Dis ; 46(2): 273-285, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36522796

RESUMO

Peroxisomes are essential organelles involved in lipid metabolisms including plasmalogen biosynthesis and ß-oxidation of very long-chain fatty acids. Peroxisomes proliferate by the growth and division of pre-existing peroxisomes. The peroxisomal membrane is elongated by Pex11ß and then divided by the dynamin-like GTPase, DLP1 (also known as DRP1 encoded by DNM1L gene), which also functions as a fission factor for mitochondria. Nucleoside diphosphate kinase 3 (NME3) localized in both peroxisomes and mitochondria generates GTP for DLP1 activity. Deficiencies of either of these factors induce abnormal morphology of peroxisomes and/or mitochondria, and are associated with central nervous system dysfunction. To investigate whether the impaired division of peroxisomes affects lipid metabolisms, we assessed the phospholipid composition of cells lacking each of the different division factors. In fibroblasts from the patients deficient in DLP1, NME3, or Pex11ß, docosahexaenoic acid (DHA, C22:6)-containing phospholipids were found to be decreased. Conversely, the levels of several fatty acids such as arachidonic acid (AA, C20:4) and oleic acid (C18:1) were elevated. Mouse embryonic fibroblasts from Drp1- and Pex11ß-knockout mice also showed a decrease in the levels of phospholipids containing DHA and AA. Collectively, these results suggest that the dynamics of organelle morphology exert marked effects on the fatty acid composition of phospholipids.


Assuntos
Ácidos Docosa-Hexaenoicos , Peroxissomos , Animais , Camundongos , Ácidos Docosa-Hexaenoicos/metabolismo , Dinaminas/metabolismo , Ácidos Graxos/metabolismo , Fibroblastos/metabolismo , Morfogênese , Nucleosídeo NM23 Difosfato Quinases/metabolismo , Peroxissomos/metabolismo , Fosfolipídeos/metabolismo
6.
J Inherit Metab Dis ; 46(2): 232-242, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36515074

RESUMO

Galactosemia is an inborn disorder of carbohydrate metabolism of which early detection can prevent severe illness. Although the assay for galactose-1-phosphate uridyltransferase (GALT) enzyme activity has been available since the 1960s, many issues prevented it from becoming universal. In order to develop the Israeli newborn screening pilot algorithm for galactosemia, flow injection analysis tandem mass spectrometry measurement of galactose-1-phosphate in archived dried blood spots from newborns with classical galactosemia, galactosemia variants, epimerase deficiency, and normal controls, was conducted. Out of 431 330 newborns screened during the pilot study (30 months), two with classical galactosemia and four with epimerase deficiency were identified and confirmed. Five false positives and no false negatives were recorded. Following this pilot study, the Israeli final and routine newborn screening algorithm, as recommended by the Advisory Committee to the National Newborn Screening Program, now consists of galactose-1-phosphate measurement integrated into the routine tandem mass spectrometry panel as the first-tier screening test, and GALT enzyme activity as the second-tier performed to identify only newborns suspected to be at risk for classical galactosemia. The GALT enzyme activity cut-off used in the final algorithm was lowered in order to avoid false positives.


Assuntos
Galactosemias , Humanos , Recém-Nascido , Galactosemias/diagnóstico , Triagem Neonatal/métodos , Projetos Piloto , UTP-Hexose-1-Fosfato Uridililtransferase , Racemases e Epimerases
7.
Harefuah ; 162(6): 344-351, 2023 Jun.
Artigo em Hebraico | MEDLINE | ID: mdl-37394435

RESUMO

INTRODUCTION: Inborn-Errors of Metabolism (IEM) are genetic disorders resulting from mutations in genes encoding proteins involved in biochemical-metabolic pathways. However, some IEMs lack specific biochemical markers. Early incorporation of next-generation-sequencing (NGS) including whole exome sequencing (WES) into the diagnostic algorithm of IEMs herein provided, increases diagnostic accuracy, permits genetic counseling and improves therapeutic options. This is exemplified by diseases affecting aminoacyl-tRNA synthetases (ARSs), enzymes involved in protein translation. Recent studies showed that supplementing amino-acids to cell-culture and patients with ARSs deficiencies resulted in improvement of biochemical and clinical parameters, respectively.


Assuntos
Erros Inatos do Metabolismo , Humanos , Erros Inatos do Metabolismo/diagnóstico , Erros Inatos do Metabolismo/genética , Erros Inatos do Metabolismo/terapia , Mutação , Biomarcadores , Aconselhamento Genético , Sequenciamento de Nucleotídeos em Larga Escala/métodos
8.
Am J Hum Genet ; 104(2): 203-212, 2019 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-30612693

RESUMO

Using exome sequencing, we have identified de novo variants in MAPK8IP3 in 13 unrelated individuals presenting with an overlapping phenotype of mild to severe intellectual disability. The de novo variants comprise six missense variants, three of which are recurrent, and three truncating variants. Brain anomalies such as perisylvian polymicrogyria, cerebral or cerebellar atrophy, and hypoplasia of the corpus callosum were consistent among individuals harboring recurrent de novo missense variants. MAPK8IP3 has been shown to be involved in the retrograde axonal-transport machinery, but many of its specific functions are yet to be elucidated. Using the CRISPR-Cas9 system to target six conserved amino acid positions in Caenorhabditis elegans, we found that two of the six investigated human alterations led to a significantly elevated density of axonal lysosomes, and five variants were associated with adverse locomotion. Reverse-engineering normalized the observed adverse effects back to wild-type levels. Combining genetic, phenotypic, and functional findings, as well as the significant enrichment of de novo variants in MAPK8IP3 within our total cohort of 27,232 individuals who underwent exome sequencing, we implicate de novo variants in MAPK8IP3 as a cause of a neurodevelopmental disorder with intellectual disability and variable brain anomalies.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Encéfalo/anormalidades , Encéfalo/metabolismo , Deficiência Intelectual/genética , Mutação , Proteínas do Tecido Nervoso/genética , Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Adolescente , Animais , Encéfalo/diagnóstico por imagem , Sistemas CRISPR-Cas , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiologia , Criança , Pré-Escolar , Simulação por Computador , Feminino , Humanos , Deficiência Intelectual/diagnóstico por imagem , Locomoção , Lisossomos/metabolismo , Masculino , Modelos Moleculares , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/metabolismo , Sequenciamento do Exoma , Adulto Jovem
9.
Pediatr Nephrol ; 37(11): 2725-2732, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35239033

RESUMO

BACKGROUND: Inborn errors of metabolism (IEM), including organic acidemias and urea cycle defects, are characterized by systemic accumulation of toxic metabolites with deleterious effect on the developing brain. While hemodialysis (HD) is most efficient in clearing IEM-induced metabolic toxins, data regarding its use during the neonatal period is scarce. METHODS: We retrospectively summarize our experience with HD in 20 neonates with IEM-induced metabolic intoxication (seven with maple syrup urine disease, 13 with primary hyperammonia), over a 16-year period, between 2004 and 2020. All patients presented with IEM-induced neurologic deterioration at 48 h to 14 days post-delivery, and were managed with HD in a pediatric intensive care setting. HD was performed through an internal jugular acute double-lumen catheter (6.5-7.0 French), using an AK-200S (Gambro, Sweden) dialysis machine and tubing, with F3 or FXpaed (Fresenius, Germany) dialyzers. RESULTS: Median (interquartile range) age and weight at presentation were 5 (3-8) days and 2830 (2725-3115) g, respectively. Two consecutive HD sessions decreased the mean leucine levels from 2281 ± 631 to 179 ± 91 µmol/L (92.1% reduction) in MSUD patients, and the mean ammonia levels from 955 ± 444 to 129 ± 55 µmol/L (86.5% reduction), in patients with hyperammonemia. HD was uneventful in all patients, and led to marked clinical improvement in 17 patients (85%). Three patients (15%) died during the neonatal period, and four died during long-term follow-up. CONCLUSIONS: Taken together, our results indicate that HD is safe, effective, and life-saving for most neonates with severe IEM-induced metabolic intoxication, when promptly performed by an experienced and multidisciplinary team. A higher resolution version of the Graphical abstract is available as Supplementary information.


Assuntos
Erros Inatos do Metabolismo , Diálise Renal , Amônia , Criança , Humanos , Recém-Nascido , Leucina , Erros Inatos do Metabolismo/complicações , Erros Inatos do Metabolismo/terapia , Diálise Renal/efeitos adversos , Diálise Renal/métodos , Estudos Retrospectivos , Ureia
10.
Proc Natl Acad Sci U S A ; 116(2): 566-574, 2019 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-30587587

RESUMO

We report a patient who presented with congenital hypotonia, hypoventilation, and cerebellar histopathological alterations. Exome analysis revealed a homozygous mutation in the initiation codon of the NME3 gene, which encodes an NDP kinase. The initiation-codon mutation leads to deficiency in NME3 protein expression. NME3 is a mitochondrial outer-membrane protein capable of interacting with MFN1/2, and its depletion causes dysfunction in mitochondrial dynamics. Consistently, the patient's fibroblasts were characterized by a slow rate of mitochondrial dynamics, which was reversed by expression of wild-type or catalytic-dead NME3. Moreover, glucose starvation caused mitochondrial fragmentation and cell death in the patient's cells. The expression of wild-type and catalytic-dead but not oligomerization-attenuated NME3 restored mitochondrial elongation. However, only wild-type NME3 sustained ATP production and viability. Thus, the separate functions of NME3 in mitochondrial fusion and NDP kinase cooperate in metabolic adaptation for cell survival in response to glucose starvation. Given the critical role of mitochondrial dynamics and energy requirements in neuronal development, the homozygous mutation in NME3 is linked to a fatal mitochondrial neurodegenerative disorder.


Assuntos
Trifosfato de Adenosina , Metabolismo Energético/genética , Homozigoto , Dinâmica Mitocondrial/genética , Nucleosídeo NM23 Difosfato Quinases , Doenças Neurodegenerativas , Trifosfato de Adenosina/genética , Trifosfato de Adenosina/metabolismo , Linhagem Celular , Sobrevivência Celular , Feminino , Humanos , Masculino , Mitocôndrias/enzimologia , Mitocôndrias/genética , Mitocôndrias/patologia , Nucleosídeo NM23 Difosfato Quinases/genética , Nucleosídeo NM23 Difosfato Quinases/metabolismo , Doenças Neurodegenerativas/enzimologia , Doenças Neurodegenerativas/genética , Doenças Neurodegenerativas/patologia
11.
J Inherit Metab Dis ; 44(2): 376-387, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-32898308

RESUMO

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by TYMP mutations and thymidine phosphorylase (TP) deficiency. Thymidine and deoxyuridine accumulate impairing the mitochondrial DNA maintenance and integrity. Clinically, patients show severe and progressive gastrointestinal and neurological manifestations. The onset typically occurs in the second decade of life and mean age at death is 37 years. Signs and symptoms of MNGIE are heterogeneous and confirmatory diagnostic tests are not routinely performed by most laboratories, accounting for common misdiagnosis. Factors predictive of progression and appropriate tests for monitoring are still undefined. Several treatment options showed promising results in restoring the biochemical imbalance of MNGIE. The lack of controlled studies with appropriate follow-up accounts for the limited evidence informing diagnostic and therapeutic choices. The International Consensus Conference (ICC) on MNGIE, held in Bologna, Italy, on 30 March to 31 March 2019, aimed at an evidence-based consensus on diagnosis, prognosis, and treatment of MNGIE among experts, patients, caregivers and other stakeholders involved in caring the condition. The conference was conducted according to the National Institute of Health Consensus Conference methodology. A consensus development panel formulated a set of statements and proposed a research agenda. Specifically, the ICC produced recommendations on: (a) diagnostic pathway; (b) prognosis and the main predictors of disease progression; (c) efficacy and safety of treatments; and (f) research priorities on diagnosis, prognosis, and treatment. The Bologna ICC on diagnosis, management and treatment of MNGIE provided evidence-based guidance for clinicians incorporating patients' values and preferences.


Assuntos
Gastroenteropatias/diagnóstico , Gastroenteropatias/terapia , Encefalomiopatias Mitocondriais/diagnóstico , Encefalomiopatias Mitocondriais/terapia , Consenso , DNA Mitocondrial/genética , Gastroenteropatias/genética , Gastroenteropatias/metabolismo , Humanos , Cooperação Internacional , Encefalomiopatias Mitocondriais/genética , Encefalomiopatias Mitocondriais/metabolismo , Mutação , Timidina Fosforilase/genética , Timidina Fosforilase/metabolismo
12.
J Inherit Metab Dis ; 44(3): 606-617, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33190319

RESUMO

Urea cycle disorders (UCDs), including OTC deficiency (OTCD), are life-threatening diseases with a broad clinical spectrum. Early diagnosis and initiation of treatment based on a newborn screening (NBS) test for OTCD with high specificity and sensitivity may contribute to reduction of the significant complications and high mortality. The efficacy of incorporating orotic acid determination into routine NBS was evaluated. Combined measurement of orotic acid and citrulline in archived dried blood spots from newborns with urea cycle disorders and normal controls was used to develop an algorithm for routine NBS for OTCD in Israel. Clinical information and genetic confirmation results were obtained from the follow-up care providers. About 1147986 newborns underwent routine NBS including orotic acid determination, 25 of whom were ultimately diagnosed with a UCD. Of 11 newborns with OTCD, orotate was elevated in seven but normal in two males with early-onset and two males with late-onset disease. Orotate was also elevated in archived dried blood spots of all seven retrospectively tested historical OTCD patients, only three of whom had originally been identified by NBS with low citrulline and elevated glutamine. Among the other UCDs emerge, three CPS1D cases and additional three retrospective CPS1D cases otherwise reported as a very rare condition. Combined levels of orotic acid and citrulline in routine NBS can enhance the detection of UCD, especially increasing the screening sensitivity for OTCD and differentiate it from CPS1D. Our data and the negligible extra cost for orotic acid determination might contribute to the discussion on screening for proximal UCDs in routine NBS.


Assuntos
Citrulina/sangue , Doença da Deficiência de Ornitina Carbomoiltransferase/diagnóstico , Ácido Orótico/sangue , Distúrbios Congênitos do Ciclo da Ureia/diagnóstico , Teste em Amostras de Sangue Seco , Feminino , Humanos , Recém-Nascido , Israel/epidemiologia , Masculino , Triagem Neonatal , Doença da Deficiência de Ornitina Carbomoiltransferase/epidemiologia , Estudos Retrospectivos , Distúrbios Congênitos do Ciclo da Ureia/epidemiologia
13.
Pediatr Blood Cancer ; 68(5): e28926, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33533561

RESUMO

BACKGROUND: Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a progressive autosomal recessive disorder characterized by cachexia, gastrointestinal (GI) dysmotility, ptosis, peripheral neuropathy, and brain magnetic resonance imaging (MRI) white matter changes. Bi-allelic TYMP mutations lead to deficient thymidine phosphorylase (TP) activity, toxic accumulation of plasma nucleosides (thymidine and deoxyuridine), nucleotide pool imbalances, and mitochondrial DNA (mtDNA) instability. Death is mainly due to GI complications: intestinal perforation, peritonitis, and/or liver failure. Based on our previous observations in three patients with MNGIE that platelet infusions resulted in a transient 40% reduction of plasma nucleoside levels, in 2005 we performed the first hematopoietic stem cell transplantation (HSCT) worldwide as a life-long source of TP in a patient with MNGIE. PROCEDURE: HSCT was performed in a total of six patients with MNGIE. The multiple factors involved in the prognosis of this cohort were analyzed and compared to the literature experience. RESULTS: Cell source was bone marrow in five patients and peripheral stem cells in one, all from fully human leukocyte antigen (HLA)-matched related donors, including four who were TYMP mutation carriers. Four of six (66%) survived compared to the 37% survival rate in the literature. Reduced intensity conditioning regimen contributed to secondary graft failure in two patients. Fifteen years post HSCT, the first transplanted patient is seemingly cured. Severe GI symptoms before transplantation were mostly irreversible and were poor prognostic factors. CONCLUSIONS: Allogenic HSCT could constitute a curative therapeutic option for carefully selected, young, presymptomatic, or mildly affected patients. Timing, donor selection, and optimal conditioning protocol are major determinants of outcome. HSCT is inadvisable in patients with advanced MNGIE disease.


Assuntos
Transplante de Células-Tronco Hematopoéticas/métodos , Pseudo-Obstrução Intestinal/terapia , Distrofia Muscular Oculofaríngea/terapia , Oftalmoplegia/congênito , Adolescente , Adulto , Criança , Estudos de Coortes , Feminino , Humanos , Masculino , Oftalmoplegia/terapia , Linhagem , Prognóstico , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
14.
Clin Genet ; 98(4): 402-407, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32683677

RESUMO

COG6-congenital disorder of glycosylation (COG6-CDG) is caused by biallelic mutations in COG6. To-date, 12 variants causing COG6-CDG in less than 20 patients have been reported. Using whole exome sequencing we identified two siblings with a novel homozygous deletion of 26 bp in COG6, creating a splicing variant (c.518_540 + 3del) and a shift in the reading frame. The phenotype of COG6-CDG includes growth and developmental retardation, microcephaly, liver and gastrointestinal disease, hypohydrosis and recurrent infections. We report two patients with novel phenotypic features including bowel malrotation and ambiguous genitalia, directing attention to the role of glycoprotein metabolism in the causation of disorders of sex development (DSD). Searching the glycomic literature, we identified 14 CDGs including males with DSD, a feature not previously accentuated. This study broadens the genetic and phenotypic spectrum of COG6-CDG and calls for increasing awareness to the central role of glycosylation processes in development of human sex and genitalia.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular/genética , Defeitos Congênitos da Glicosilação/genética , Transtornos do Desenvolvimento Sexual/genética , Oxigenases de Função Mista/genética , Defeitos Congênitos da Glicosilação/mortalidade , Defeitos Congênitos da Glicosilação/fisiopatologia , Transtornos do Desenvolvimento Sexual/mortalidade , Transtornos do Desenvolvimento Sexual/fisiopatologia , Feminino , Glicosilação , Homozigoto , Humanos , Recém-Nascido , Masculino , Mutação/genética , Fenótipo , Deleção de Sequência/genética , Irmãos , Sequenciamento do Exoma
15.
Brain ; 142(12): 3876-3891, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31688942

RESUMO

Ohtahara syndrome, early infantile epileptic encephalopathy with a suppression burst EEG pattern, is an aetiologically heterogeneous condition starting in the first weeks or months of life with intractable seizures and profound developmental disability. Using whole exome sequencing, we identified biallelic DMXL2 mutations in three sibling pairs with Ohtahara syndrome, belonging to three unrelated families. Siblings in Family 1 were compound heterozygous for the c.5135C>T (p.Ala1712Val) missense substitution and the c.4478C>G (p.Ser1493*) nonsense substitution; in Family 2 were homozygous for the c.4478C>A (p.Ser1493*) nonsense substitution and in Family 3 were homozygous for the c.7518-1G>A (p.Trp2507Argfs*4) substitution. The severe developmental and epileptic encephalopathy manifested from the first day of life and was associated with deafness, mild peripheral polyneuropathy and dysmorphic features. Early brain MRI investigations in the first months of life revealed thin corpus callosum with brain hypomyelination in all. Follow-up MRI scans in three patients revealed progressive moderate brain shrinkage with leukoencephalopathy. Five patients died within the first 9 years of life and none achieved developmental, communicative or motor skills following birth. These clinical findings are consistent with a developmental brain disorder that begins in the prenatal brain, prevents neural connections from reaching the expected stages at birth, and follows a progressive course. DMXL2 is highly expressed in the brain and at synaptic terminals, regulates v-ATPase assembly and activity and participates in intracellular signalling pathways; however, its functional role is far from complete elucidation. Expression analysis in patient-derived skin fibroblasts demonstrated absence of the DMXL2 protein, revealing a loss of function phenotype. Patients' fibroblasts also exhibited an increased LysoTracker® signal associated with decreased endolysosomal markers and degradative processes. Defective endolysosomal homeostasis was accompanied by impaired autophagy, revealed by lower LC3II signal, accumulation of polyubiquitinated proteins, and autophagy receptor p62, with morphological alterations of the autolysosomal structures on electron microscopy. Altered lysosomal homeostasis and defective autophagy were recapitulated in Dmxl2-silenced mouse hippocampal neurons, which exhibited impaired neurite elongation and synaptic loss. Impaired lysosomal function and autophagy caused by biallelic DMXL2 mutations affect neuronal development and synapse formation and result in Ohtahara syndrome with profound developmental impairment and reduced life expectancy.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Autofagia/genética , Encéfalo/fisiopatologia , Proteínas do Tecido Nervoso/genética , Espasmos Infantis/genética , Encéfalo/diagnóstico por imagem , Criança , Pré-Escolar , Progressão da Doença , Eletroencefalografia , Feminino , Humanos , Lactente , Lisossomos/fisiologia , Imageamento por Ressonância Magnética , Masculino , Mutação , Linhagem , Espasmos Infantis/diagnóstico por imagem , Espasmos Infantis/fisiopatologia , Sequenciamento do Exoma
16.
Int J Mol Sci ; 21(21)2020 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-33126676

RESUMO

Peroxisomes proliferate by sequential processes comprising elongation, constriction, and scission of peroxisomal membrane. It is known that the constriction step is mediated by a GTPase named dynamin-like protein 1 (DLP1) upon efficient loading of GTP. However, mechanism of fuelling GTP to DLP1 remains unknown in mammals. We earlier show that nucleoside diphosphate (NDP) kinase-like protein, termed dynamin-based ring motive-force organizer 1 (DYNAMO1), generates GTP for DLP1 in a red alga, Cyanidioschyzon merolae. In the present study, we identified that nucleoside diphosphate kinase 3 (NME3), a mammalian homologue of DYNAMO1, localizes to peroxisomes. Elongated peroxisomes were observed in cells with suppressed expression of NME3 and fibroblasts from a patient lacking NME3 due to the homozygous mutation at the initiation codon of NME3. Peroxisomes proliferated by elevation of NME3 upon silencing the expression of ATPase family AAA domain containing 1, ATAD1. In the wild-type cells expressing catalytically-inactive NME3, peroxisomes were elongated. These results suggest that NME3 plays an important role in peroxisome division in a manner dependent on its NDP kinase activity. Moreover, the impairment of peroxisome division reduces the level of ether-linked glycerophospholipids, ethanolamine plasmalogens, implying the physiological importance of regulation of peroxisome morphology.


Assuntos
Dinaminas/metabolismo , Nucleosídeo NM23 Difosfato Quinases/metabolismo , Peroxissomos/metabolismo , Frações Subcelulares/metabolismo , Sequência de Aminoácidos , Animais , Células HeLa , Homozigoto , Humanos , Rodófitas , Homologia de Sequência
17.
Am J Hum Genet ; 99(5): 1172-1180, 2016 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-27773429

RESUMO

Glycine is a major neurotransmitter that activates inhibitory glycine receptors and is a co-agonist for excitatory glutamatergic N-methyl-D-aspartate (NMDA) receptors. Two transporters, GLYT1 and GLYT2, regulate extracellular glycine concentrations within the CNS. Dysregulation of the extracellular glycine has been associated with hyperekplexia and nonketotic hyperglycinemia. Here, we report four individuals from two families who presented at birth with facial dysmorphism, encephalopathy, arthrogryposis, hypotonia progressing to hypertonicity with startle-like clonus, and respiratory failure. Only one individual survived the respiratory failure and was weaned off ventilation but has significant global developmental delay. Mildly elevated cerebrospinal fluid (CSF) glycine and normal serum glycine were observed in two individuals. In both families, we identified truncating mutations in SLC6A9, encoding GLYT1. We demonstrate that pharmacologic or genetic abolishment of GlyT1 activity in mice leads to mildly elevated glycine in the CSF but not in blood. Additionally, previously reported slc6a9-null mice and zebrafish mutants also display phenotypes consistent with the affected individuals we examined. Our data suggest that truncating SLC6A9 mutations lead to a distinct human neurological syndrome hallmarked by mildly elevated CSF glycine and normal serum glycine.


Assuntos
Artrogripose/genética , Proteínas da Membrana Plasmática de Transporte de Glicina/genética , Glicina/líquido cefalorraquidiano , Hiperglicinemia não Cetótica/genética , Animais , Artrogripose/diagnóstico , Pré-Escolar , Feminino , Deleção de Genes , Regulação da Expressão Gênica , Glicina/sangue , Proteínas da Membrana Plasmática de Transporte de Glicina/metabolismo , Humanos , Hiperglicinemia não Cetótica/diagnóstico , Lactente , Recém-Nascido , Masculino , Camundongos , Camundongos Knockout , Linhagem
18.
J Hum Genet ; 64(6): 589-595, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30903008

RESUMO

Translation of mitochondrial-specific DNA is required for proper mitochondrial function and energy production. For this purpose, an elaborate network of dedicated molecular machinery including initiation, elongation and termination factors exists. We describe a patient with an unusual phenotype and a novel homozygous missense variant in TUFM (c.344A>C; p.His115Pro), encoding mtDNA translation elongating factor Tu (EFTu). To date, only four patients have been reported with bi-allelic mutations in TUFM, leading to combined oxidative phosphorylation deficiency 4 (COXPD4) characterized by severe early-onset lactic acidosis and progressive fatal infantile encephalopathy. The patient presented here expands the phenotypic features of TUFM-related disease, exhibiting lactic acidosis and dilated cardiomyopathy without progressive encephalopathy. This warrants the inclusion of TUFM in differential diagnosis of metabolic cardiomyopathy. Cases that further refine genotype-phenotype associations and characterize the molecular basis of mitochondrial disorders allow clinicians to predict disease prognosis, greatly impacting patient care, as well as provide families with reproductive planning options.


Assuntos
Acidose Láctica/genética , Cardiomiopatias/genética , Erros Inatos do Metabolismo/genética , Mitocôndrias/genética , Doenças Mitocondriais/genética , Proteínas Mitocondriais/genética , Fator Tu de Elongação de Peptídeos/genética , Acidose Láctica/fisiopatologia , Sequência de Aminoácidos/genética , Cardiomiopatias/fisiopatologia , Consanguinidade , DNA Mitocondrial/genética , Feminino , Homozigoto , Humanos , Lactente , Masculino , Erros Inatos do Metabolismo/fisiopatologia , Doenças Mitocondriais/fisiopatologia , Mutação , Fosforilação Oxidativa , Sequenciamento do Exoma
19.
J Inherit Metab Dis ; 42(6): 1192-1230, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-30982989

RESUMO

In 2012, we published guidelines summarizing and evaluating late 2011 evidence for diagnosis and therapy of urea cycle disorders (UCDs). With 1:35 000 estimated incidence, UCDs cause hyperammonemia of neonatal (~50%) or late onset that can lead to intellectual disability or death, even while effective therapies do exist. In the 7 years that have elapsed since the first guideline was published, abundant novel information has accumulated, experience on newborn screening for some UCDs has widened, a novel hyperammonemia-causing genetic disorder has been reported, glycerol phenylbutyrate has been introduced as a treatment, and novel promising therapeutic avenues (including gene therapy) have been opened. Several factors including the impact of the first edition of these guidelines (frequently read and quoted) may have increased awareness among health professionals and patient families. However, under-recognition and delayed diagnosis of UCDs still appear widespread. It was therefore necessary to revise the original guidelines to ensure an up-to-date frame of reference for professionals and patients as well as for awareness campaigns. This was accomplished by keeping the original spirit of providing a trans-European consensus based on robust evidence (scored with GRADE methodology), involving professionals on UCDs from nine countries in preparing this consensus. We believe this revised guideline, which has been reviewed by several societies that are involved in the management of UCDs, will have a positive impact on the outcomes of patients by establishing common standards, and spreading and harmonizing good practices. It may also promote the identification of knowledge voids to be filled by future research.


Assuntos
Guias de Prática Clínica como Assunto , Distúrbios Congênitos do Ciclo da Ureia/diagnóstico , Distúrbios Congênitos do Ciclo da Ureia/terapia , Adulto , Idade de Início , Criança , Consenso , Endocrinologia/organização & administração , Endocrinologia/normas , Europa (Continente)/epidemiologia , Humanos , Hiperamonemia/diagnóstico , Hiperamonemia/epidemiologia , Hiperamonemia/terapia , Recém-Nascido , Triagem Neonatal/métodos , Triagem Neonatal/normas , Pediatria/organização & administração , Pediatria/normas , Guias de Prática Clínica como Assunto/normas , Distúrbios Congênitos do Ciclo da Ureia/epidemiologia
20.
Metab Brain Dis ; 34(2): 557-563, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30637540

RESUMO

D-glycerate 2 kinase (DGK) is an enzyme that mediates the conversion of D-glycerate, an intermediate metabolite of serine and fructose metabolism, to 2-phosphoglycerate. Deficiency of DGK leads to accumulation of D-glycerate in various tissues and its massive excretion in urine. D-glyceric aciduria (DGA) is an autosomal recessive metabolic disorder caused by mutations in the GLYCTK gene. The clinical spectrum of DGA is highly variable, ranging from severe progressive infantile encephalopathy to a practically asymptomatic condition. We describe a male patient from a consanguineous Arab family with infantile onset of DGA, characterized by profound psychomotor retardation, progressive microcephaly, intractable seizures, cortical blindness and deafness. Consecutive brain MR imaging showed an evolving brain atrophy, thinning of the corpus callosum and diffuse abnormal white matter signals. Whole exome sequencing identified the homozygous missense variant in the GLYCTK gene [c.455 T > C, NM_145262.3], which affected a highly conserved leucine residue located at a domain of yet unknown function of the enzyme [p.Leu152Pro, NP_660305]. In silico analysis of the variant supported its pathogenicity. A review of the 15 previously reported patients, together with the current one, confirms a clear association between DGA and severe neurological impairment. Yet, future studies of additional patients with DGA are required to better understand the clinical phenotype and pathogenesis.


Assuntos
Encefalopatias/metabolismo , Epilepsia/metabolismo , Hiperoxalúria Primária/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Encefalopatias/genética , Criança , Epilepsia/diagnóstico , Epilepsia/genética , Ácidos Glicéricos/metabolismo , Humanos , Hiperoxalúria Primária/genética , Lactente , Masculino , Mutação/genética , Fenótipo , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Espasmos Infantis/genética , Espasmos Infantis/metabolismo
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