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1.
Nat Commun ; 11(1): 4038, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-32788587

RESUMO

Asparaginyl-tRNA synthetase1 (NARS1) is a member of the ubiquitously expressed cytoplasmic Class IIa family of tRNA synthetases required for protein translation. Here, we identify biallelic missense and frameshift mutations in NARS1 in seven patients from three unrelated families with microcephaly and neurodevelopmental delay. Patient cells show reduced NARS1 protein, impaired NARS1 activity and impaired global protein synthesis. Cortical brain organoid modeling shows reduced proliferation of radial glial cells (RGCs), leading to smaller organoids characteristic of microcephaly. Single-cell analysis reveals altered constituents of both astrocytic and RGC lineages, suggesting a requirement for NARS1 in RGC proliferation. Our findings demonstrate that NARS1 is required to meet protein synthetic needs and to support RGC proliferation in human brain development.


Assuntos
Aspartato-tRNA Ligase/deficiência , Aspartato-tRNA Ligase/genética , Córtex Cerebral/patologia , Microcefalia/genética , Células-Tronco Neurais/patologia , Organoides/patologia , Aminoacil-RNA de Transferência/genética , Adolescente , Adulto , Sequência de Bases , Diferenciação Celular , Proliferação de Células , Tamanho Celular , Sobrevivência Celular , Criança , Família , Feminino , Fibroblastos/metabolismo , Fibroblastos/patologia , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Antígeno Ki-67/metabolismo , Masculino , Mutação/genética , Células-Tronco Neurais/metabolismo , Neuroglia/metabolismo , Linhagem , Adulto Jovem
2.
PLoS One ; 15(7): e0235655, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32628740

RESUMO

Biallelic variants in RNU4ATAC, a non-coding gene transcribed into the minor spliceosome component U4atac snRNA, are responsible for three rare recessive developmental diseases, namely Taybi-Linder/MOPD1, Roifman and Lowry-Wood syndromes. Next-generation sequencing of clinically heterogeneous cohorts (children with either a suspected genetic disorder or a congenital microcephaly) recently identified mutations in this gene, illustrating how profoundly these technologies are modifying genetic testing and assessment. As RNU4ATAC has a single non-coding exon, the bioinformatic prediction algorithms assessing the effect of sequence variants on splicing or protein function are irrelevant, which makes variant interpretation challenging to molecular diagnostic laboratories. In order to facilitate and improve clinical diagnostic assessment and genetic counseling, we present i) an update of the previously reported RNU4ATAC mutations and an analysis of the genetic variations affecting this gene using the Genome Aggregation Database (gnomAD) resource; ii) the pathogenicity prediction performances of scores computed based on an RNA structure prediction tool and of those produced by the Combined Annotation Dependent Depletion tool for the 285 RNU4ATAC variants identified in patients or in large-scale sequencing projects; iii) a method, based on a cellular assay, that allows to measure the effect of RNU4ATAC variants on splicing efficiency of a minor (U12-type) reporter intron. Lastly, the concordance of bioinformatic predictions and cellular assay results was investigated.


Assuntos
RNA Nuclear Pequeno/metabolismo , Spliceossomos/metabolismo , Criança , Bases de Dados Genéticas , Nanismo/genética , Nanismo/patologia , Retardo do Crescimento Fetal/genética , Retardo do Crescimento Fetal/patologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Variação Genética , Humanos , Microcefalia/genética , Microcefalia/patologia , Conformação de Ácido Nucleico , Osteocondrodisplasias/genética , Osteocondrodisplasias/patologia , Processamento de RNA , RNA Nuclear Pequeno/química , RNA Nuclear Pequeno/genética
3.
Am J Hum Genet ; 107(2): 352-363, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32693025

RESUMO

MORC2 encodes an ATPase that plays a role in chromatin remodeling, DNA repair, and transcriptional regulation. Heterozygous variants in MORC2 have been reported in individuals with autosomal-dominant Charcot-Marie-Tooth disease type 2Z and spinal muscular atrophy, and the onset of symptoms ranges from infancy to the second decade of life. Here, we present a cohort of 20 individuals referred for exome sequencing who harbor pathogenic variants in the ATPase module of MORC2. Individuals presented with a similar phenotype consisting of developmental delay, intellectual disability, growth retardation, microcephaly, and variable craniofacial dysmorphism. Weakness, hyporeflexia, and electrophysiologic abnormalities suggestive of neuropathy were frequently observed but were not the predominant feature. Five of 18 individuals for whom brain imaging was available had lesions reminiscent of those observed in Leigh syndrome, and five of six individuals who had dilated eye exams had retinal pigmentary abnormalities. Functional assays revealed that these MORC2 variants result in hyperactivation of epigenetic silencing by the HUSH complex, supporting their pathogenicity. The described set of morphological, growth, developmental, and neurological findings and medical concerns expands the spectrum of genetic disorders resulting from pathogenic variants in MORC2.


Assuntos
Adenosina Trifosfatases/genética , Anormalidades Craniofaciais/genética , Transtornos do Crescimento/genética , Mutação/genética , Transtornos do Neurodesenvolvimento/genética , Fatores de Transcrição/genética , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Doenças Genéticas Inatas/genética , Heterozigoto , Humanos , Lactente , Deficiência Intelectual/genética , Masculino , Microcefalia/genética , Pessoa de Meia-Idade , Fenótipo , Adulto Jovem
4.
Medicine (Baltimore) ; 99(22): e20507, 2020 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-32481472

RESUMO

RATIONALE: Asparagine synthetase deficiency (ASNSD) refers to a congenital metabolic abnormality caused by mutation in the asparagine synthetase (ASNS) gene encoded by chromosome 7q21. Herein, we report the first case of ASNSD in China, in which novel ASNS mutations were identified. PATIENT CONCERNS: A 6-month-old boy presented with a 4-month history of microcephaly and psychomotor developmental retardation and a 2-month history of epilepsy. Four months after birth, magnetic resonance imaging demonstrated a giant cyst in the right lateral ventricle, and a ventriculoperitoneal shunt was placed. Video electroencephalography showed a hypsarrhythmia pattern with a string of tonic-clonic and myoclonic seizures. On admission, physical examination showed microcephaly. Neurologic examination showed a decreased tension in the trunk muscles and an increased tension in the extremity muscles; tendon hyperreflexia was noted, and bilateral pathologic reflexes were positive. DIAGNOSIS: A diagnosed of congenital microcephaly was made. Whole-exome sequencing revealed a heterozygous deletion mutation c.666_667delCT (p.L2221Lfs*5) in exon 6 of the ASNS gene and a heterozygous missense mutation c.1424C>T (p.T457I) in exon 13 of the ASNS gene. INTERVENTIONS: After admission, intravenous adrenocorticotropic hormone and oral topiramate was administrated for 4 weeks, while the seizures persisted. Then, levetiracetam and clonazepam were added. OUTCOMES: After the follow-up period of 18 months, video electroencephalography showed that complex episodes disappeared with changes in multiple focal spike and sharp waves; 1 focal attack arising from the left occipital region and 2 focal attacks arising from the right middle temporal and the right occipital region were recorded. LESSONS: This is the first case of ASNSD in China. We identified 2 novel mutations (c.666_667delCT and c.1424C>T) in the ASNS gene, which expands the ASNS gene mutation profile and will be beneficial for genetic diagnosis.


Assuntos
Aspartato-Amônia Ligase/genética , Epilepsia/genética , Microcefalia/genética , Anticonvulsivantes/uso terapêutico , Aspartato-Amônia Ligase/deficiência , China , Clonazepam/uso terapêutico , Eletroencefalografia , Epilepsia/tratamento farmacológico , Humanos , Lactente , Levetiracetam/uso terapêutico , Masculino , Mutação de Sentido Incorreto
5.
Cytogenet Genome Res ; 160(6): 309-315, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32599602

RESUMO

Warburg micro syndrome (WARBM) is a rare autosomal recessive disorder characterized by microcephaly, cortical dysplasia, intellectual disability, ocular abnormalities, spastic diplegia, and microgenitalia. WARBM has 4 subtypes arising from pathogenic variants in 4 genes (RAB18, RAB3GAP1, RAB3GAP2, and TBC1D20). Here, we report on a patient with a homozygous pathogenic c.665delC (p.Pro222HisfsTer30) variant in the RAB3GAP1 gene identified by whole-exome sequencing (WES) analyses. Only his father was a heterozygous carrier, and homozygosity mapping analysis of the WES data revealed large loss-of-heterozygosity regions in both arms of chromosome 2, interpreted as uniparental isodisomy. This uniparental disomy pattern could be due to paternal meiosis I nondisjunction because of the preserved heterozygosity in the pericentromeric region. This report provides novel insights, including a rare form of UPD, usage of homozygosity mapping analysis for the evaluation of isodisomy, and the first reported case of WARBM1 as a result of uniparental isodisomy.


Assuntos
Anormalidades Múltiplas/genética , Catarata/congênito , Cromossomos Humanos Par 2/genética , Córnea/anormalidades , Homozigoto , Hipogonadismo/genética , Deficiência Intelectual/genética , Microcefalia/genética , Atrofia Óptica/genética , Dissomia Uniparental/genética , Sequenciamento Completo do Exoma , Adolescente , Adulto , Catarata/genética , Feminino , Humanos , Lactente , Perda de Heterozigosidade/genética , Masculino , Pais , Polimorfismo de Nucleotídeo Único/genética , Proteínas rab3 de Ligação ao GTP/genética
6.
Nucleic Acids Res ; 48(12): 6672-6684, 2020 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-32504494

RESUMO

Hereditary mutations in polynucleotide kinase-phosphatase (PNKP) result in a spectrum of neurological pathologies ranging from neurodevelopmental dysfunction in microcephaly with early onset seizures (MCSZ) to neurodegeneration in ataxia oculomotor apraxia-4 (AOA4) and Charcot-Marie-Tooth disease (CMT2B2). Consistent with this, PNKP is implicated in the repair of both DNA single-strand breaks (SSBs) and DNA double-strand breaks (DSBs); lesions that can trigger neurodegeneration and neurodevelopmental dysfunction, respectively. Surprisingly, however, we did not detect a significant defect in DSB repair (DSBR) in primary fibroblasts from PNKP patients spanning the spectrum of PNKP-mutated pathologies. In contrast, the rate of SSB repair (SSBR) is markedly reduced. Moreover, we show that the restoration of SSBR in patient fibroblasts collectively requires both the DNA kinase and DNA phosphatase activities of PNKP, and the fork-head associated (FHA) domain that interacts with the SSBR protein, XRCC1. Notably, however, the two enzymatic activities of PNKP appear to affect different aspects of disease pathology, with reduced DNA phosphatase activity correlating with neurodevelopmental dysfunction and reduced DNA kinase activity correlating with neurodegeneration. In summary, these data implicate reduced rates of SSBR, not DSBR, as the source of both neurodevelopmental and neurodegenerative pathology in PNKP-mutated disease, and the extent and nature of this reduction as the primary determinant of disease severity.


Assuntos
Quebras de DNA de Cadeia Dupla , Quebras de DNA de Cadeia Simples , Enzimas Reparadoras do DNA/genética , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Proteína 1 Complementadora Cruzada de Reparo de Raio-X/genética , Apraxias/genética , Apraxias/patologia , Doença de Charcot-Marie-Tooth/genética , Doença de Charcot-Marie-Tooth/patologia , Reparo do DNA/genética , Fibroblastos/metabolismo , Fibroblastos/patologia , Humanos , Microcefalia/genética , Microcefalia/patologia , Mutação/genética , Convulsões/genética , Convulsões/patologia
7.
Nucleic Acids Res ; 48(13): 7239-7251, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32542379

RESUMO

Telomeres cap the ends of eukaryotic chromosomes and distinguish them from broken DNA ends to suppress DNA damage response, cell cycle arrest and genomic instability. Telomeres are elongated by telomerase to compensate for incomplete replication and nuclease degradation and to extend the proliferation potential of germ and stem cells and most cancers. However, telomeres in somatic cells gradually shorten with age, ultimately leading to cellular senescence. Hoyeraal-Hreidarsson syndrome (HHS) is characterized by accelerated telomere shortening and diverse symptoms including bone marrow failure, immunodeficiency, and neurodevelopmental defects. HHS is caused by germline mutations in telomerase subunits, factors essential for its biogenesis and recruitment to telomeres, and in the helicase RTEL1. While diverse phenotypes were associated with RTEL1 deficiency, the telomeric role of RTEL1 affected in HHS is yet unknown. Inducible ectopic expression of wild-type RTEL1 in patient fibroblasts rescued the cells, enabled telomerase-dependent telomere elongation and suppressed the abnormal cellular phenotypes, while silencing its expression resulted in gradual telomere shortening. Our observations reveal an essential role of the RTEL1 C-terminus in facilitating telomerase action at the telomeric 3' overhang. Thus, the common etiology for HHS is the compromised telomerase action, resulting in telomere shortening and reduced lifespan of telomerase positive cells.


Assuntos
DNA Helicases/metabolismo , Disceratose Congênita/genética , Retardo do Crescimento Fetal/genética , Deficiência Intelectual/genética , Microcefalia/genética , Homeostase do Telômero , Células Cultivadas , DNA Helicases/química , DNA Helicases/genética , Fibroblastos/metabolismo , Humanos , Domínios Proteicos , Telomerase/genética , Telomerase/metabolismo , Encurtamento do Telômero
8.
Nat Struct Mol Biol ; 27(5): 438-449, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32398829

RESUMO

The SLX4 tumor suppressor is a scaffold that plays a pivotal role in several aspects of genome protection, including homologous recombination, interstrand DNA crosslink repair and the maintenance of common fragile sites and telomeres. Here, we unravel an unexpected direct interaction between SLX4 and the DNA helicase RTEL1, which, until now, were viewed as having independent and antagonistic functions. We identify cancer and Hoyeraal-Hreidarsson syndrome-associated mutations in SLX4 and RTEL1, respectively, that abolish SLX4-RTEL1 complex formation. We show that both proteins are recruited to nascent DNA, tightly co-localize with active RNA pol II, and that SLX4, in complex with RTEL1, promotes FANCD2/RNA pol II co-localization. Importantly, disrupting the SLX4-RTEL1 interaction leads to DNA replication defects in unstressed cells, which are rescued by inhibiting transcription. Our data demonstrate that SLX4 and RTEL1 interact to prevent replication-transcription conflicts and provide evidence that this is independent of the nuclease scaffold function of SLX4.


Assuntos
DNA Helicases/metabolismo , Replicação do DNA , Recombinases/metabolismo , Transcrição Genética , DNA Helicases/genética , Disceratose Congênita/genética , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/genética , Proteína do Grupo de Complementação D2 da Anemia de Fanconi/metabolismo , Retardo do Crescimento Fetal/genética , Mutação em Linhagem Germinativa , Células HeLa , Humanos , Deficiência Intelectual/genética , Microcefalia/genética , Recombinases/genética
9.
Gene ; 753: 144816, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32473250

RESUMO

Hemizygosity of the MIR17HG gene encoding the miR-17 ~ 92 cluster is associated with Feingold syndrome 2 characterized by intellectual disability, skeletal abnormalities, short stature, and microcephaly. Here, we report on a female with a de novo 13q31.3 microduplication encompassing MIR17HG but excluding GPC5. She presented developmental delay, skeletal and digital abnormalities, and features such as tall stature and macrocephaly mirroring those of Feingold syndrome 2 patients. The limited extent of the proband's rearrangement to the miR cluster and the corresponding normal expression level of the neighboring GPC5 in her cells, together with previously described data on affected individuals of two families carrying overlapping duplications of the miR-17 ~ 92 cluster that comprise part of GPC5, who likewise presented macrocephaly, developmental delay, as well as skeletal, digital and stature abnormalities, allow to define a new syndrome due to independent microduplication of the miR-17 ~ 92 cluster.


Assuntos
Transtornos Cromossômicos/genética , Pálpebras/anormalidades , Deficiência Intelectual/genética , Deformidades Congênitas dos Membros/genética , MicroRNAs/genética , Microcefalia/genética , Fístula Traqueoesofágica/genética , Adolescente , Deleção Cromossômica , Cromossomos Humanos Par 13/genética , Hibridização Genômica Comparativa/métodos , Deficiências do Desenvolvimento/genética , Nanismo/genética , Feminino , Duplicação Gênica/genética , Glipicanas/genética , Glipicanas/metabolismo , Humanos , Fenótipo
10.
BMC Med Genet ; 21(1): 99, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32393352

RESUMO

BACKGROUND: To date, at least 746 genes have been identified to cause intellectual disability (ID). Among them, mutations in the Methyl CpG binding protein 2 (MECP2) gene are the leading cause of Rett syndrome and associated ID. METHODS: Considering the large number of ID-associated genes, we applied trio-based whole-exome sequencing (trio-WES) and in silico analysis for genetic diagnosis of 294 children with ID. RESULTS: Three de novo heterozygous mutations [NM_004992.3: c.502C > T, p.(Arg168*), c.916C > T, p.(Arg306Cys), and c.879C > G, p.(Ile293Met)] in MECP2 were identified in three unrelated girls. The first two mutations were detected in two patients who were diagnosed as typical Rett syndrome, X-linked ID and psychomotor retardation. The third mutation (c.879C > G), a previously unreported, was found in a 6-year-old girl with ID, microcephaly, severe underweight and psychomotor retardation. Particularly, this extremely rare de novo mutation (DNM) is located in the transcriptional repression domain (TRD) of MECP2, where at least 62 different causal mutations are identified. CONCLUSIONS: We identified three DNMs in MECP2 in a cohort of 294 individuals with ID. The novel c.879C > G mutation, as a likely pathogenic allele, may become a risk factor associated with X-linked ID, microcephaly and psychomotor retardation.


Assuntos
Predisposição Genética para Doença , Deficiência Intelectual/genética , Proteína 2 de Ligação a Metil-CpG/genética , Síndrome de Rett/genética , Criança , Pré-Escolar , Feminino , Heterozigoto , Humanos , Deficiência Intelectual/patologia , Microcefalia/genética , Microcefalia/patologia , Mutação , Linhagem , Fenótipo , Síndrome de Rett/patologia , Sequenciamento Completo do Exoma
11.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 37(5): 539-542, 2020 May 10.
Artigo em Chinês | MEDLINE | ID: mdl-32335881

RESUMO

OBJECTIVE: To explore the genetic basis of a proband with distinctive facial features, global developmental delay, seizures and hypoplasia of corpus callosum through next generation sequencing (NGS). METHODS: Genomic DNA was extracted from peripheral blood samples of the proband and his family members. Whole exome and flanking sequences were screened by NGS. Suspected variants were verified by Sanger sequencing. RESULTS: The proband was found to carry a heterozygous c.2824G>T (p.G942X) variant of the ZEB2 gene, which was verified by Sanger sequencing to be a de novo variant. CONCLUSION: The heterozygous c.2824G>T (p.G942X) variant of the ZEB2 gene probably underlies the Mowat-Wilson syndrome in the proband.


Assuntos
Facies , Variação Genética , Doença de Hirschsprung , Deficiência Intelectual , Microcefalia , Homeobox 2 de Ligação a E-box com Dedos de Zinco , Heterozigoto , Doença de Hirschsprung/genética , Humanos , Deficiência Intelectual/genética , Microcefalia/genética , Sequenciamento Completo do Exoma , Homeobox 2 de Ligação a E-box com Dedos de Zinco/genética
12.
Medicine (Baltimore) ; 99(16): e19813, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32311999

RESUMO

RATIONALE: Wiedemann-Steiner syndrome (WDSTS, online mendelian inheritance in man 605130) is a rare autosomal dominant disorder characterized by hypertrichosis cubiti. Here, we report a Chinese boy who do not show the characteristic of hypertrichosis cubiti, and was misdiagnosed as blepharophimosis-ptosis-epicanthus inversus syndrome at first. We found a de novo frameshift mutation (p.Glu390Lysfs*10) in the KMT2A gene, which was not reported before. Our study increases the cohort of Chinese WDSTS patients, and expand the WDSTS phenotypic and variation spectrum. PATIENT CONCERNS: The patient demonstrated typical craniofacial features of blepharophimosis-ptosis-epicanthus inversus syndrome, including small palpebral fissures, ptosis, telecanthus, and epicanthus inversus, besides he had congenital heart disease (ventricular septal defects), strabismus, hypotonia, amblyopia, delayed speech and language development, delayed psychomotor development, and amblyopia (HP:0000646) which was not reported before. DIAGNOSIS: FOXL2 gene was cloned and sequenced, however, there was no mutation detected in this patient. The result of Chromosomal microarray analysis was normal. The patient was diagnosed as WDSTS by whole exome sequencing. INTERVENTIONS: The patient received cardiac surgery, frontalis suspension and regular speech and occupational therapy. He also treated with growth hormone (GH). OUTCOMES: The patient's symptoms are improved after cardiac surgery and frontalis suspension, he can express himself well now and had a 10 cm gain in height. LESSONS: As the relationship between genotype and phenotype becomes more and more clear, WES is incredibly powerful tool to diagnose the disease of WDSTS.


Assuntos
Anormalidades Múltiplas/genética , Blefarofimose/diagnóstico , Contratura/genética , Transtornos do Crescimento/diagnóstico , Transtornos do Crescimento/genética , Cardiopatias Congênitas/diagnóstico , Histona-Lisina N-Metiltransferase/genética , Hipertricose/congênito , Deficiência Intelectual/genética , Microcefalia/genética , Proteína de Leucina Linfoide-Mieloide/genética , Anormalidades da Pele/diagnóstico , Anormalidades Urogenitais/diagnóstico , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/terapia , Grupo com Ancestrais do Continente Asiático/genética , Criança , Contratura/diagnóstico , Contratura/terapia , Erros de Diagnóstico , Facies , Genótipo , Transtornos do Crescimento/etiologia , Transtornos do Crescimento/terapia , Hormônio do Crescimento/uso terapêutico , Cardiopatias Congênitas/cirurgia , Humanos , Hipertricose/diagnóstico , Hipertricose/etiologia , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/terapia , Masculino , Microcefalia/diagnóstico , Microcefalia/terapia , Mutação , Fenótipo , Resultado do Tratamento , Sequenciamento Completo do Exoma/métodos
13.
Am J Hum Genet ; 106(4): 467-483, 2020 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-32220291

RESUMO

The RNA editing enzyme ADAR2 is essential for the recoding of brain transcripts. Impaired ADAR2 editing leads to early-onset epilepsy and premature death in a mouse model. Here, we report bi-allelic variants in ADARB1, the gene encoding ADAR2, in four unrelated individuals with microcephaly, intellectual disability, and epilepsy. In one individual, a homozygous variant in one of the double-stranded RNA-binding domains (dsRBDs) was identified. In the others, variants were situated in or around the deaminase domain. To evaluate the effects of these variants on ADAR2 enzymatic activity, we performed in vitro assays with recombinant proteins in HEK293T cells and ex vivo assays with fibroblasts derived from one of the individuals. We demonstrate that these ADAR2 variants lead to reduced editing activity on a known ADAR2 substrate. We also demonstrate that one variant leads to changes in splicing of ADARB1 transcript isoforms. These findings reinforce the importance of RNA editing in brain development and introduce ADARB1 as a genetic etiology in individuals with intellectual disability, microcephaly, and epilepsy.


Assuntos
Adenosina Desaminase/genética , Predisposição Genética para Doença/genética , Variação Genética/genética , Deficiência Intelectual/genética , Microcefalia/genética , Proteínas de Ligação a RNA/genética , Convulsões/genética , Alelos , Processamento Alternativo/genética , Criança , Pré-Escolar , Células HEK293 , Humanos , Masculino , Processamento de RNA/genética
14.
BMC Neurol ; 20(1): 58, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32061250

RESUMO

BACKGROUND: Primary microcephaly is defined as reduced occipital-frontal circumference noticeable before 36 weeks of gestation. Large amount of insults might lead to microcephaly including infections, hypoxia and genetic mutations. More than 16 genes are described in autosomal recessive primary microcephaly. However, the cause of microcephaly remains unclear in many cases after extensive investigations and genetic screening. CASE PRESENTATION: Here, we described the case of a boy with primary microcephaly who presented to a neurology clinic with short stature, global development delay, dyskinetic movement, strabismus and dysmorphic features. We performed microcephaly investigations and genetic panels. Then, we performed whole-exome sequencing to identify any genetic cause. Microcephaly investigations and genetic panels were negative, but we found a new D317V homozygous mutation in TELOE-2 interacting protein 2 (TTI2) gene by whole-exome sequencing. TTI2 is implicated in DNA damage response and mutation in that gene was previously described in mental retardation, autosomal recessive 39. CONCLUSIONS: We described the first French Canadian case with primary microcephaly and global developmental delay secondary to a new D317V homozygous mutation in TTI2 gene. Our report also highlights the importance of TTI2 protein in brain development.


Assuntos
Microcefalia/genética , Malformações do Sistema Nervoso/genética , Sequenciamento Completo do Exoma , Canadá , Pré-Escolar , Testes Genéticos , Homozigoto , Humanos , Lactente , Masculino , Mutação
16.
J Hum Genet ; 65(4): 387-396, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31965062

RESUMO

NGLY1 deficiency is the first and only autosomal recessive congenital disorder of N-linked deglycosylation (NGLY1-CDDG). To date, no patients with NGLY1 deficiency has been reported from mainland China or East Asia in English literature. Here, we present six patients with a diagnosis of NGLY1-CDDG on the basis of clinical phenotype, genetic testing, and functional studies. We retrospectively analyzed clinical phenotypes and NGLY1 genotypes of six cases from four families. Informed consent was obtained for diagnosis and treatment. In-silico tools and in vitro enzyme activity assays were used to determine pathogenicity of NGLY1 varaints. All patients had typical features of NGLY1-CDDG, including global developmental delay, microcephaly, hypotonia, hypertransaminasemia, alacrimia, and feeding difficulty. Dysmorphic features found in our patients include flat nasal bridge, loose and hollow cheeks, short stature, malnutrition, and ptosis. Pachylosis could be a novel cutaneous feature that may be explained by lack of sweat. We found three novel variants, including one missense (c.982C > G/p.Arg328Gly), one splice site (c.1003+3A > G), and one frame-shift (c.1637-1652delCATCTTTTGCTTATAT/p.Ser546PhefsTer) variant. All mutations were predicted to be disease causing with in-silico prediction tools, and affected at least one feature of gene splicing. Protein modeling showed missense variants may affect covalent bonding within the protein structure, or interrupt active/binding amino-acid residues. In vitro studies indicated that proteins carrying missense variants (p.Arg328Gly and p.Tyr342Cys) lost the enzyme activity. We expanded clinical phenotype and genetic mutation spectrum of NGLY1-CDDG by reporting six cases, three novel variants, and novel clinical features from mainland China.


Assuntos
Defeitos Congênitos da Glicosilação/genética , Deficiências do Desenvolvimento/genética , Oftalmopatias Hereditárias/genética , Transtornos da Alimentação e da Ingestão de Alimentos/genética , Doenças do Aparelho Lacrimal/genética , Microcefalia/genética , Hipotonia Muscular/genética , Mutação , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/deficiência , Defeitos Congênitos da Glicosilação/patologia , Deficiências do Desenvolvimento/patologia , Oftalmopatias Hereditárias/patologia , Transtornos da Alimentação e da Ingestão de Alimentos/patologia , Feminino , Humanos , Lactente , Doenças do Aparelho Lacrimal/patologia , Masculino , Microcefalia/patologia , Hipotonia Muscular/patologia , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/genética
17.
Clin Dysmorphol ; 29(2): 97-100, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31929334

RESUMO

Deletion of the 1q43q44 chromosomal region has been related to a clinical syndrome characterized by neurodevelopmental delay, intellectual disability, microcephaly, congenital abnormality of the corpus callosum, and epilepsy and dysmorphic features. A wide variability of the clinical features have been linked to the contiguous deleted genes and incomplete penetrance has been observed too. Here, we report a 4-years-old boy with microcephaly, neurodevelopmental delay, and cardiac atrial septal defect, who had a de-novo 117 Kb 1q43-q44 microdeletion. The deleted chromosomal region encompassed the two genes SDCCAG8 and AKT3. The characteristics of the deletion and the clinical condition of the patient suggest a pathogenic role of the 1q43-q44 deletion, supporting a pivotal role of AKT3 gene in the expression of the clinical phenotype.


Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 1 , Haploinsuficiência/genética , Microcefalia/diagnóstico , Microcefalia/genética , Proteínas Proto-Oncogênicas c-akt/genética , Transtornos Psicomotores/diagnóstico , Transtornos Psicomotores/genética , Pré-Escolar , Hibridização Genômica Comparativa , Estudos de Associação Genética , Predisposição Genética para Doença , Humanos , Masculino
18.
FASEB J ; 34(1): 1319-1330, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31914610

RESUMO

Posttranslational modifications enhance the functional diversity of the proteome by modifying the substrates. The UFM1 cascade is a novel ubiquitin-like modification system. The mutations in UFM1, its E1 (UBA5) and E2 (UFC1), have been identified in patients with microcephaly. However, its pathological mechanisms remain unclear. Herein, we observed the disruption of the UFM1 cascade in Drosophila neuroblasts (NBs) decreased the number of NBs, leading to a smaller brain size. The lack of ufmylation in NBs resulted in an increased mitotic index and an extended G2/M phase, indicating a defect in mitotic progression. In addition, live imaging of the embryos revealed an impaired E3 ligase (Ufl1) function resulted in premature entry into mitosis and failed cellularization. Even worse, the embryonic lethality occurred as early as within the first few mitotic cycles following the depletion of Ufm1. Knockdown of ufmylation in the fixed embryos exhibited severe phenotypes, including detached centrosomes, defective microtubules, and DNA bridge. Furthermore, we observed that the UFM1 cascade could alter the level of phosphorylation on tyrosine-15 of CDK1 (pY15-CDK1), which is a negative regulator of the G2 to M transition. These findings yield unambiguous evidence suggesting that the UFM1 cascade is a microcephaly-causing factor that regulates the progression of the cell cycle at mitosis phase entry.


Assuntos
Divisão Celular , Proteínas de Drosophila , Embrião não Mamífero/enzimologia , Fase G2 , Microcefalia , Ubiquitina-Proteína Ligases , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Microcefalia/enzimologia , Microcefalia/genética , Transdução de Sinais/genética , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo
19.
Brain Dev ; 42(3): 302-306, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31882333

RESUMO

Autosomal recessive PRUNE1 mutations on chromosome 1q21.3 are reported to cause a neurodevelopmental disorder with microcephaly, hypotonia, and variable brain malformations. Here, we report a Japanese case with a reported PRUNE1 mutation whose brain magnetic resonance imaging (MRI) showed specific imaging findings that have not been reported before. The patient was a 12-month-old girl, the first child of healthy and nonconsanguineous Japanese parents. She showed global developmental delay, intellectual disability, hypotonia, spastic quadriparesis, and hyperreflexia. Brain MRI showed cerebral and cerebellar atrophy, thin corpus callosum, white matter changes, and abnormal signal intensity of the brainstem, all of which were reported in the literature. In addition, we emphasize the three following imaging findings: a transient cerebral subcortical white matter lesion, atrophy of the midbrain and pontine tegmentum with a preserved pontine base, and abnormal signal intensity of the bilateral swelling putamina and medial portions of the thalami, which emerged after 4 years of age. The whole-exome sequencing (WES) analysis performed at the age of 4 years identified biallelic PRUNE1 variants, namely compound heterozygous mutations (c.[316G > A];[540 T > A],p.[Asp106Asn];[Cys180*]). Although the diagnosis of PRUNE1-related disorder requires WES, we think that these new characteristic MRI findings may help in the diagnosis of PRUNE1-related disorder.


Assuntos
Encéfalo/patologia , Microcefalia , Transtornos do Neurodesenvolvimento , Monoéster Fosfórico Hidrolases/genética , Encéfalo/diagnóstico por imagem , Pré-Escolar , Feminino , Humanos , Japão , Imagem por Ressonância Magnética , Microcefalia/genética , Microcefalia/patologia , Microcefalia/fisiopatologia , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/patologia , Transtornos do Neurodesenvolvimento/fisiopatologia
20.
Elife ; 82019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31794381

RESUMO

Occludin (OCLN) mutations cause human microcephaly and cortical malformation. A tight junction component thought absent in neuroepithelium after neural tube closure, OCLN isoform-specific expression extends into corticogenesis. Full-length and truncated isoforms localize to neuroprogenitor centrosomes, but full-length OCLN transiently localizes to plasma membranes while only truncated OCLN continues at centrosomes throughout neurogenesis. Mimicking human mutations, full-length OCLN depletion in mouse and in human CRISPR/Cas9-edited organoids produce early neuronal differentiation, reduced progenitor self-renewal and increased apoptosis. Human neural progenitors were more severely affected, especially outer radial glial cells, which mouse embryonic cortex lacks. Rodent and human mutant progenitors displayed reduced proliferation and prolonged M-phase. OCLN interacted with mitotic spindle regulators, NuMA and RAN, while full-length OCLN loss impaired spindle pole morphology, astral and mitotic microtubule integrity. Thus, early corticogenesis requires full-length OCLN to regulate centrosome organization and dynamics, revealing a novel role for this tight junction protein in early brain development.


Assuntos
Córtex Cerebral/crescimento & desenvolvimento , Córtex Cerebral/metabolismo , Ocludina/metabolismo , Junções Íntimas/metabolismo , Aneuploidia , Animais , Apoptose , Sistemas CRISPR-Cas , Diferenciação Celular , Proliferação de Células , Centrossomo/metabolismo , Córtex Cerebral/patologia , Modelos Animais de Doenças , Edição de Genes , Humanos , Camundongos , Camundongos Knockout , Microcefalia/genética , Microcefalia/patologia , Microtúbulos/metabolismo , Mutagênese , Mutação , Neurogênese/genética , Neurogênese/fisiologia , Ocludina/genética , Fuso Acromático/metabolismo , Junções Íntimas/genética
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