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1.
Genet Med ; 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31761904

RESUMO

PURPOSE: Pathogenic variants in neuroblastoma-amplified sequence (NBAS) cause an autosomal recessive disorder with a wide range of symptoms affecting liver, skeletal system, and brain, among others. There is a continuously growing number of patients but a lack of systematic and quantitative analysis. METHODS: Individuals with biallelic variants in NBAS were recruited within an international, multicenter study, including novel and previously published patients. Clinical variables were analyzed with log-linear models and visualized by mosaic plots; facial profiles were investigated via DeepGestalt. The structure of the NBAS protein was predicted using computational methods. RESULTS: One hundred ten individuals from 97 families with biallelic pathogenic NBAS variants were identified, including 26 novel patients with 19 previously unreported variants, giving a total number of 86 variants. Protein modeling redefined the ß-propeller domain of NBAS. Based on the localization of missense variants and in-frame deletions, three clinical subgroups arise that differ significantly regarding main clinical features and are directly related to the affected region of the NBAS protein: ß-propeller (combined phenotype), Sec39 (infantile liver failure syndrome type 2/ILFS2), and C-terminal (short stature, optic atrophy, and Pelger-Huët anomaly/SOPH). CONCLUSION: We define clinical subgroups of NBAS-associated disease that can guide patient management and point to domain-specific functions of NBAS.

2.
Brain ; 2019 Nov 05.
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.

4.
Ann Clin Transl Neurol ; 6(5): 968-973, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31139695

RESUMO

Developmental and epileptic encephalopathies are characterized by infantile seizures and psychomotor delay. Glycosylphosphatidylinositol biosynthesis defects, resulting in impaired tethering of various proteins to the cell surface, represent the underlying pathology in some patients. One of the genes involved, PIGP, has recently been associated with infantile seizures and developmental delay in two siblings. Here, we report the second family with a markedly overlapping phenotype due to a homozygous frameshift mutation (c.456delA;p.Glu153Asnfs*34) in PIGP. Flow cytometry of patient granulocytes confirmed reduced expression of glycosylphosphatidylinositol-anchored proteins as functional consequence. Our findings corroborate PIGP as a monogenic disease gene for developmental and epileptic encephalopathy.

5.
Clin Genet ; 95(6): 734-735, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30887513

RESUMO

A hemizygous variant in the HNRNPH2 gene causes MRXSB in a male individual.

6.
Nat Commun ; 10(1): 708, 2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30755616

RESUMO

Aminoacyl tRNA synthetases (ARSs) link specific amino acids with their cognate transfer RNAs in a critical early step of protein translation. Mutations in ARSs have emerged as a cause of recessive, often complex neurological disease traits. Here we report an allelic series consisting of seven novel and two previously reported biallelic variants in valyl-tRNA synthetase (VARS) in ten patients with a developmental encephalopathy with microcephaly, often associated with early-onset epilepsy. In silico, in vitro, and yeast complementation assays demonstrate that the underlying pathomechanism of these mutations is most likely a loss of protein function. Zebrafish modeling accurately recapitulated some of the key neurological disease traits. These results provide both genetic and biological insights into neurodevelopmental disease and pave the way for further in-depth research on ARS related recessive disorders and precision therapies.


Assuntos
Encefalopatias/genética , Microcefalia/genética , Valina-tRNA Ligase/genética , Alelos , Animais , Encefalopatias/enzimologia , Encefalopatias/patologia , Linhagem Celular , Modelos Animais de Doenças , Epilepsia/enzimologia , Epilepsia/genética , Epilepsia/patologia , Feminino , Fibroblastos , Técnicas de Inativação de Genes , Predisposição Genética para Doença , Humanos , Mutação com Perda de Função , Masculino , Microcefalia/enzimologia , Microcefalia/patologia , Modelos Moleculares , Transtornos do Neurodesenvolvimento/enzimologia , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/patologia , Linhagem , Prosencéfalo/patologia , Peixe-Zebra
7.
Cell ; 176(3): 505-519.e22, 2019 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-30612738

RESUMO

Genomic instability can be a hallmark of both human genetic disease and cancer. We identify a deleterious UBQLN4 mutation in families with an autosomal recessive syndrome reminiscent of genome instability disorders. UBQLN4 deficiency leads to increased sensitivity to genotoxic stress and delayed DNA double-strand break (DSB) repair. The proteasomal shuttle factor UBQLN4 is phosphorylated by ATM and interacts with ubiquitylated MRE11 to mediate early steps of homologous recombination-mediated DSB repair (HRR). Loss of UBQLN4 leads to chromatin retention of MRE11, promoting non-physiological HRR activity in vitro and in vivo. Conversely, UBQLN4 overexpression represses HRR and favors non-homologous end joining. Moreover, we find UBQLN4 overexpressed in aggressive tumors. In line with an HRR defect in these tumors, UBQLN4 overexpression is associated with PARP1 inhibitor sensitivity. UBQLN4 therefore curtails HRR activity through removal of MRE11 from damaged chromatin and thus offers a therapeutic window for PARP1 inhibitor treatment in UBQLN4-overexpressing tumors.


Assuntos
Proteínas de Transporte/genética , Proteínas Nucleares/genética , Proteínas de Transporte/metabolismo , Cromatina/metabolismo , DNA , Quebras de DNA de Cadeia Dupla , Dano ao DNA/genética , Reparo do DNA por Junção de Extremidades , Proteínas de Ligação a DNA/metabolismo , Feminino , Instabilidade Genômica , Mutação em Linhagem Germinativa , Recombinação Homóloga , Humanos , Proteína Homóloga a MRE11/genética , Proteína Homóloga a MRE11/metabolismo , Masculino , Neoplasias/genética , Neoplasias/metabolismo , Proteínas Nucleares/metabolismo , Cultura Primária de Células , Reparo de DNA por Recombinação
8.
Orphanet J Rare Dis ; 13(1): 112, 2018 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-29986738

RESUMO

BACKGROUND: Our objective was to evaluate children with metabolic diseases in paediatric palliative home care (PPC) and the process of decision-making. This study was conducted as single-centre retrospective cohort study of patients in the care of a large specialized PPC team. RESULTS: Between 01/2013 and 09/2016, 198 children, adolescents and young adults were in the care of our PPC team. Twenty-nine (14.6%) of these patients had metabolic conditions. Median age at referral was 2.6 years (0-24), median duration of care 352 days (3-2248) and median number of home visits 13 (1-80). Most patients are still alive (16; 55.2%). Median number of drugs administered was 5 (range 0-12), antiepileptics were given most frequently. Symptom burden was high in all children with metabolic disorders at referral and remained high throughout care. Predominant symptoms were gastrointestinal, respiratory and neurologic symptoms. Children with metabolic conditions, who were referred to PPC younger than 1 year of age had a shorter period of care and died earlier compared to those children, who were referred to PPC later in their lives (older than 10 years of age). Eleven (37.9%) of the children initially had no resuscitation restrictions and 7 (53.8%) of those who died, did so on ICU. CONCLUSIONS: About 15% of children with life-limiting conditions in PPC present with metabolic diseases. Symptom burden is high with neurologic, respiratory and gastrointestinal symptoms being the most frequent and most of those being difficult to treat. In these children, particular attention needs to be addressed to advance care planning.

9.
Am J Hum Genet ; 103(2): 305-316, 2018 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-30057029

RESUMO

Next-generation sequencing combined with international data sharing has enormously facilitated identification of new disease-associated genes and mutations. This is particularly true for genetically extremely heterogeneous entities such as neurodevelopmental disorders (NDDs). Through exome sequencing and world-wide collaborations, we identified and assembled 20 individuals with de novo variants in FBXO11. They present with mild to severe developmental delay associated with a range of features including short (4/20) or tall (2/20) stature, obesity (5/20), microcephaly (4/19) or macrocephaly (2/19), behavioral problems (17/20), seizures (5/20), cleft lip or palate or bifid uvula (3/20), and minor skeletal anomalies. FBXO11 encodes a member of the F-Box protein family, constituting a subunit of an E3-ubiquitin ligase complex. This complex is involved in ubiquitination and proteasomal degradation and thus in controlling critical biological processes by regulating protein turnover. The identified de novo aberrations comprise two large deletions, ten likely gene disrupting variants, and eight missense variants distributed throughout FBXO11. Structural modeling for missense variants located in the CASH or the Zinc-finger UBR domains suggests destabilization of the protein. This, in combination with the observed spectrum and localization of identified variants and the lack of apparent genotype-phenotype correlations, is compatible with loss of function or haploinsufficiency as an underlying mechanism. We implicate de novo missense and likely gene disrupting variants in FBXO11 in a neurodevelopmental disorder with variable intellectual disability and various other features.

11.
Neuropediatrics ; 49(5): 330-338, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29940663

RESUMO

BACKGROUND: Primary microcephaly and profound global developmental delay have been considered the core clinical phenotype in patients with bi-allelic PRUNE1 mutations. METHODS: Linkage analysis and whole-exome sequencing (WES) in a multiplex family and extraction of further cases from a WES repository containing 571 children with severe developmental disabilities and neurologic symptoms. RESULTS: We identified bi-allelic PRUNE1 mutations in twelve children from six unrelated families. All patients who survived beyond the first 6 months of life had early-onset global developmental delay, bilateral spastic paresis, dysphagia and difficult-to-treat seizures, while congenital or later-evolving microcephaly was not a consistent finding. Brain MRI showed variable anomalies with progressive cerebral and cerebellar atrophies and T2-hyperintense brain stem lesions. Peripheral neuropathy was documented in five cases. Disease course was progressive in all patients and eight children died in the first or early second decade of life. In addition to the previously reported missense mutation p.(Asp106Asn), we observed a novel homozygous missense variant p.(Leu172Pro) and a homozygous contiguous gene deletion encompassing most of the PRUNE1 gene and part of the neighboring BNIPL gene. CONCLUSIONS: PRUNE1 deficiency causes severe early-onset disease affecting the central and peripheral nervous systems. Microcephaly is probably not a universal feature.

12.
J Inherit Metab Dis ; 2018 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-29721919

RESUMO

Congenital disorders of glycosylation (CDG) have a broad spectrum of clinical manifestations. They can affect multiple organ systems, including skin and subcutaneous tissue. We report on an infant with severe ichthyosis caused by MPDU1 mutations. The case illustrates that skin manifestations are an important feature of CDG syndromes. Therefore, metabolic investigations should be included in the workup of infantile ichthyosis disorders.

13.
Pediatrics ; 141(Suppl 5): S501-S505, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29610180

RESUMO

Blue diaper syndrome (BDS) (Online Mendelian Inheritance in Man number 211000) is an extremely rare disorder that was first described in 1964. The characteristic finding is a bluish discoloration of urine spots in the diapers of affected infants. Additional clinical features of the first described patients included diarrhea, inadequate weight gain, hypercalcemia, and nephrocalcinosis. An intestinal defect of tryptophan absorption was postulated as the underlying pathology. However, functional evidence for this theory is lacking. No genetic cause has been identified so far. Here, we report on a boy who presented with neonatal-onset diarrhea, metabolic acidosis, transient hepatopathy, recurrent hypoglycemia, and blue-stained urine spots in his diapers. An ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry analysis of urine samples at different time points demonstrated the constant presence of indigo derivatives, thereby confirming the diagnosis of BDS. Of note, the visibility of indigo derivatives in the urine was highly dependent on the urine's pH. To identify the underlying genetic cause of the disease, whole-exome sequencing was performed, leading to the identification of a homozygous frameshift mutation in proprotein convertase subtilisin/kexin type 1 (PCSK1; NM_000439.4: c.679del, p.[Val227Leufs*12]). PCSK1 encodes prohormone convertase 1/3, and mutations within this gene have been reported as a rare cause of early-onset malabsorptive diarrhea and multiple endocrine dysfunction. In our report, we suggest that BDS can be caused by PCSK1 mutations.

14.
J Pediatr ; 196: 309-313.e3, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29395179

RESUMO

We demonstrate that a heterozygous nuclear variant in the gene encoding mitochondrial complex I subunit NDUFV1 aggravates the cellular phenotype in the presence of a mitochondrial DNA variant in complex I subunit ND1. Our findings suggest that heterozygous variants could be more significant in inherited mitochondrial diseases than hitherto assumed.

15.
Parkinsonism Relat Disord ; 50: 119-120, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29429647

RESUMO

Increasing evidence supports a link between multiple system atrophy and coenzyme Q10 (CoQ10) biosynthesis. However, so far this knowledge was not translated into tangible benefits for affected patients. Poor bioavailability of oral CoQ10 might constitute a major problem. Current research suggests that 4-hydroxybenzoic acid might constitute an interesting alternative treatment option.

16.
Mol Genet Metab ; 123(3): 289-291, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29246431

RESUMO

Primary disorders of the human coenzyme Q10 (CoQ10) biosynthesis pathway are a known cause of severe pediatric diseases. So far, oral administration of CoQ10 is the only treatment strategy for affected individuals. However, the real benefit of CoQ10 supplementation remains questionable and clinical studies regarding efficiency are lacking. Here we provide an outlook on novel treatment approaches using CoQ precursor compounds. These metabolic bypass strategies might be a promising alternative for oral CoQ10 supplementation regimens.

17.
J Inherit Metab Dis ; 40(6): 853-860, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28687938

RESUMO

Recently, CLPB deficiency has been shown to cause a genetic syndrome with cataracts, neutropenia, and 3-methylglutaconic aciduria. Surprisingly, the neurological presentation ranges from completely unaffected to patients with virtual absence of development. Muscular hypo- and hypertonia, movement disorder and progressive brain atrophy are frequently reported. We present the foetal, peri- and neonatal features of 31 patients, of which five are previously unreported, using a newly developed clinical severity scoring system rating the clinical, metabolic, imaging and other findings weighted by the age of onset. Our data are illustrated by foetal and neonatal videos. The patients were classified as having a mild (n = 4), moderate (n = 13) or severe (n = 14) disease phenotype. The most striking feature of the severe subtype was the neonatal absence of voluntary movements in combination with ventilator dependency and hyperexcitability. The foetal and neonatal presentation mirrored the course of disease with respect to survival (current median age 17.5 years in the mild group, median age of death 35 days in the severe group), severity and age of onset of all findings evaluated. CLPB deficiency should be considered in neonates with absence of voluntary movements, respiratory insufficiency and swallowing problems, especially if associated with 3-methylglutaconic aciduria, neutropenia and cataracts. Being an important differential diagnosis of hyperekplexia (exaggerated startle responses), we advise performing urinary organic acid analysis, blood cell counts and ophthalmological examination in these patients. The neonatal presentation of CLPB deficiency predicts the course of disease in later life, which is extremely important for counselling.


Assuntos
Catarata/metabolismo , Endopeptidase Clp/deficiência , Erros Inatos do Metabolismo/metabolismo , Neutropenia/metabolismo , Adolescente , Adulto , Atrofia/metabolismo , Encefalopatias , Criança , Pré-Escolar , Feminino , Feto/metabolismo , Humanos , Hiperecplexia/metabolismo , Lactente , Recém-Nascido , Masculino , Transtornos dos Movimentos/metabolismo , Fenótipo , Adulto Jovem
18.
Stem Cell Res Ther ; 8(1): 150, 2017 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-28646906

RESUMO

BACKGROUND: Disorders of the oxidative phosphorylation (OXPHOS) system represent a large group among the inborn errors of metabolism. The most frequently observed biochemical defect is isolated deficiency of mitochondrial complex I (CI). No effective treatment strategies for CI deficiency are so far available. The purpose of this study was to investigate whether and how mesenchymal stem cells (MSCs) are able to modulate metabolic function in fibroblast cell models of CI deficiency. METHODS: We used human and murine fibroblasts with a defect in the nuclear DNA encoded NDUFS4 subunit of CI. Fibroblasts were co-cultured with MSCs under different stress conditions and intercellular mitochondrial transfer was assessed by flow cytometry and fluorescence microscopy. Reactive oxygen species (ROS) levels were measured using MitoSOX-Red. Protein levels of CI were analysed by blue native polyacrylamide gel electrophoresis (BN-PAGE). RESULTS: Direct cellular interactions and mitochondrial transfer between MSCs and human as well as mouse fibroblast cell lines were demonstrated. Mitochondrial transfer was visible in 13.2% and 6% of fibroblasts (e.g. fibroblasts containing MSC mitochondria) for human and mouse cell lines, respectively. The transfer rate could be further stimulated via treatment of cells with TNF-α. MSCs effectively lowered cellular ROS production in NDUFS4-deficient fibroblast cell lines (either directly via co-culture or indirectly via incubation of cell lines with cell-free MSC supernatant). However, CI protein expression and activity were not rescued by MSC treatment. CONCLUSION: This study demonstrates the interplay between MSCs and fibroblast cell models of isolated CI deficiency including transfer of mitochondria as well as modulation of cellular ROS levels. Further exploration of these cellular interactions might help to develop MSC-based treatment strategies for human CI deficiency.


Assuntos
Complexo I de Transporte de Elétrons , Fibroblastos/enzimologia , Células-Tronco Mesenquimais/enzimologia , Mitocôndrias/enzimologia , NADH Desidrogenase , Fosforilação Oxidativa , Animais , Técnicas de Cocultura , Complexo I de Transporte de Elétrons/deficiência , Complexo I de Transporte de Elétrons/metabolismo , Fibroblastos/citologia , Humanos , Células-Tronco Mesenquimais/citologia , Camundongos , Mitocôndrias/genética , NADH Desidrogenase/deficiência , NADH Desidrogenase/metabolismo
19.
Eur J Hum Genet ; 25(9): 1092-1095, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28612835

RESUMO

Coexistence of different hereditary diseases is a known phenomenon in populations with a high consanguinity rate. The resulting clinical phenotypes are extremely challenging for physicians involved in the care of these patients. Here we describe a 6-year-old boy with co-occurrence of a homozygous splice defect in OSTM1, causing infantile malignant osteopetrosis, and a loss-of-function variant in MANEAL, which has not been associated with human disease so far. The child suffered from severe infantile-onset neurodegeneration that could not be stopped by bone marrow transplantation. Magnetic resonance imaging demonstrated global brain atrophy and showed hypointensities of globus pallidus, corpora mamillaria, and cerebral peduncles, which were comparable to findings in neurodegeneration with brain iron accumulation disorders. LC-MS/MS analysis of urine and cerebrospinal fluid samples revealed a distinct metabolic profile with accumulation of mannose tetrasaccharide molecules, suggestive of an oligosaccharide storage disease. Our results demonstrate that exome sequencing is a very effective tool in dissecting complex neurological diseases. Moreover, we suggest that MANEAL is an interesting candidate gene that should be considered in the context of neurological disorders with brain iron accumulation and/or indications of an oligosaccharide storage disease.


Assuntos
Encefalopatias Metabólicas/genética , Encéfalo/diagnóstico por imagem , Distúrbios do Metabolismo do Ferro/genética , Manosidases/genética , Proteínas de Membrana/genética , Mutação , Doenças Neurodegenerativas/genética , Ubiquitina-Proteína Ligases/genética , Encefalopatias Metabólicas/diagnóstico , Criança , Diagnóstico Diferencial , Humanos , Distúrbios do Metabolismo do Ferro/diagnóstico , Masculino , Manose/líquido cefalorraquidiano , Manose/urina , Doenças Neurodegenerativas/diagnóstico
20.
Nat Commun ; 8: 15824, 2017 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-28604674

RESUMO

Across a variety of Mendelian disorders, ∼50-75% of patients do not receive a genetic diagnosis by exome sequencing indicating disease-causing variants in non-coding regions. Although genome sequencing in principle reveals all genetic variants, their sizeable number and poorer annotation make prioritization challenging. Here, we demonstrate the power of transcriptome sequencing to molecularly diagnose 10% (5 of 48) of mitochondriopathy patients and identify candidate genes for the remainder. We find a median of one aberrantly expressed gene, five aberrant splicing events and six mono-allelically expressed rare variants in patient-derived fibroblasts and establish disease-causing roles for each kind. Private exons often arise from cryptic splice sites providing an important clue for variant prioritization. One such event is found in the complex I assembly factor TIMMDC1 establishing a novel disease-associated gene. In conclusion, our study expands the diagnostic tools for detecting non-exonic variants and provides examples of intronic loss-of-function variants with pathological relevance.


Assuntos
Perfilação da Expressão Gênica , Doenças Mitocondriais/genética , Análise de Sequência de RNA , Técnicas e Procedimentos Diagnósticos , Humanos , Processamento de RNA
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