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1.
BMC Med Genet ; 20(1): 101, 2019 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-31174490

RESUMO

BACKGROUND: N-terminal acetylation is a common protein modification in human cells and is catalysed by N-terminal acetyltransferases (NATs), mostly cotranslationally. The NAA10-NAA15 (NatA) protein complex is the major NAT, responsible for acetylating ~ 40% of human proteins. Recently, NAA10 germline variants were found in patients with the X-linked lethal Ogden syndrome, and in other familial or de novo cases with variable degrees of developmental delay, intellectual disability (ID) and cardiac anomalies. METHODS: Here we report a novel NAA10 (NM_003491.3) c.248G > A, p.(R83H) missense variant in NAA10 which was detected by whole exome sequencing in two unrelated boys with intellectual disability, developmental delay, ADHD like behaviour, very limited speech and cardiac abnormalities. We employ in vitro acetylation assays to functionally test the impact of this variant on NAA10 enzyme activity. RESULTS: Functional characterization of NAA10-R83H by in vitro acetylation assays revealed a reduced enzymatic activity of monomeric NAA10-R83H. This variant is modelled to have an altered charge density in the acetyl-coenzyme A (Ac-CoA) binding region of NAA10. CONCLUSIONS: We show that NAA10-R83H has a reduced monomeric catalytic activity, likely due to impaired enzyme-Ac-CoA binding. Our data support a model where reduced NAA10 and/or NatA activity cause the phenotypes observed in the two patients.


Assuntos
Acetiltransferases/genética , Deficiência Intelectual/genética , Microcefalia/genética , Mutação de Sentido Incorreto , Acetiltransferase N-Terminal A/genética , Acetiltransferase N-Terminal E/genética , Acetilação , Acetiltransferases/metabolismo , Sequência de Aminoácidos , Pré-Escolar , Humanos , Lactente , Masculino , Modelos Moleculares , Acetiltransferase N-Terminal A/química , Acetiltransferase N-Terminal A/metabolismo , Acetiltransferase N-Terminal E/química , Acetiltransferase N-Terminal E/metabolismo , Fenótipo , Domínios Proteicos , Homologia de Sequência de Aminoácidos , Sequenciamento Completo do Exoma
2.
Nat Commun ; 10(1): 2612, 2019 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-31197141

RESUMO

Primary microcephaly is caused by mutations in genes encoding centrosomal proteins including WDR62 and KIF2A. However, mechanisms underlying human microcephaly remain elusive. By creating mutant mice and human cerebral organoids, here we found that WDR62 deletion resulted in a reduction in the size of mouse brains and organoids due to the disruption of neural progenitor cells (NPCs), including outer radial glia (oRG). WDR62 ablation led to retarded cilium disassembly, long cilium, and delayed cell cycle progression leading to decreased proliferation and premature differentiation of NPCs. Mechanistically, WDR62 interacts with and promotes CEP170's localization to the basal body of primary cilium, where CEP170 recruits microtubule-depolymerizing factor KIF2A to disassemble cilium. WDR62 depletion reduced KIF2A's basal body localization, and enhanced KIF2A expression partially rescued deficits in cilium length and NPC proliferation. Thus, modeling microcephaly with cerebral organoids and mice reveals a WDR62-CEP170-KIF2A pathway promoting cilium disassembly, disruption of which contributes to microcephaly.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Cinesina/metabolismo , Microcefalia/patologia , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Fosfoproteínas/metabolismo , Proteínas Repressoras/metabolismo , Animais , Técnicas de Cultura de Células , Proteínas de Ciclo Celular/genética , Diferenciação Celular , Linhagem Celular , Proliferação de Células , Cílios/metabolismo , Modelos Animais de Doenças , Feminino , Técnicas de Inativação de Genes , Humanos , Masculino , Camundongos , Camundongos Knockout , Microcefalia/genética , Proteínas Associadas aos Microtúbulos/genética , Proteínas do Tecido Nervoso/genética , Células-Tronco Neurais/citologia , Células-Tronco Neurais/patologia , Neuroglia/citologia , Neuroglia/patologia , Organoides/patologia , Fosfoproteínas/genética , RNA Interferente Pequeno/metabolismo
3.
Nat Commun ; 10(1): 2588, 2019 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-31197172

RESUMO

The brain is a genomic mosaic shaped by cellular responses to genome damage. Here, we manipulate somatic genome stability by conditional Knl1 deletion from embryonic mouse brain. KNL1 mutations cause microcephaly and KNL1 mediates the spindle assembly checkpoint, a safeguard against chromosome missegregation and aneuploidy. We find that following Knl1 deletion, segregation errors in mitotic neural progenitor cells give rise to DNA damage on the missegregated chromosomes. This triggers rapid p53 activation and robust apoptotic and microglial phagocytic responses that extensively eliminate cells with somatic genome damage, thus causing microcephaly. By leaving only karyotypically normal progenitors to continue dividing, these mechanisms provide a second safeguard against brain somatic aneuploidy. Without Knl1 or p53-dependent safeguards, genome-damaged cells are not cleared, alleviating microcephaly, but paradoxically leading to total pre-weaning lethality. Thus, mitotic genome damage activates robust responses to eliminate somatic mutant cells, which if left unpurged, can impact brain and organismal fitness.


Assuntos
Aneuploidia , Microcefalia/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Células-Tronco Neurais/fisiologia , Proteína Supressora de Tumor p53/metabolismo , Animais , Apoptose/genética , Segregação de Cromossomos/genética , Dano ao DNA/genética , Modelos Animais de Doenças , Embrião de Mamíferos , Instabilidade Genômica , Humanos , Cinetocoros/metabolismo , Camundongos , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/genética , Cultura Primária de Células , Deleção de Sequência , Fuso Acromático/metabolismo
4.
Cytogenet Genome Res ; 158(1): 25-31, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31055587

RESUMO

Diagnosing a complex genetic syndrome and correctly assigning the concomitant phenotypic traits to a well-defined clinical form is often a medical challenge. In this work, we report the analysis of a family with complex phenotypes, including microcephaly, intellectual disability, dysmorphic features, and polydactyly in the proband, with the aim of adding new aspects for obtaining a clear diagnosis. We performed array-comparative genomic hybridization and quantitative reverse transcriptase PCR (qRT-PCR) analyses. We identified a deletion of chromosome 20p12.1 involving the macrodomain containing 2/mono-ADP ribosylhydrolase 2 gene (MACROD2) in several members of the family. This gene is actually not associated with a specific syndrome but with congenital anomalies of multiple organs. qRT-PCR showed higher levels of a MACROD2 mRNA isoform in the individuals carrying the deletion. Our results, together with other data reported in the literature, support the hypothesis that the deletion in MACROD2 can affect correct embryonic development and that the presence of another associated event, such as epigenetic modifications at the MACROD2 locus, can influence the level of severity of the pathology.


Assuntos
Anormalidades Múltiplas/genética , Enzimas Reparadoras do DNA/genética , Hidrolases/genética , Deficiência Intelectual/genética , Rim/anormalidades , Microcefalia/genética , Pâncreas/anormalidades , Polidactilia/genética , Deleção de Sequência , Adulto , Cromossomos Humanos Par 20/genética , Cromossomos Humanos Par 20/ultraestrutura , Hibridização Genômica Comparativa , Enzimas Reparadoras do DNA/deficiência , Enzimas Reparadoras do DNA/fisiologia , Desenvolvimento Embrionário/genética , Feminino , Humanos , Hidrolases/deficiência , Hidrolases/fisiologia , Masculino , Linhagem , Fenótipo , Transtornos Psicomotores/genética
5.
Gene ; 704: 97-102, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30978478

RESUMO

In the current study, we report three cases of Asparagine Synthetase (ASNS) Deficiency from two consanguineous families. Family 1 had two early neonatal deaths due to a novel mutation in the ASNS gene c.788C > T (p.S263F) and both the children presented with microcephaly and one of them had severe intracranial haemorrhage. The proband from the second family was homozygous for c.146G > A (p.R49Q) and manifested myoclonic seizures, developmental delay, coarse hair and diffuse cortical atrophy. Molecular docking studies of both the mutations revealed alteration in the ligand binding site. Till date, 26 mutations were reported in ASNS gene in 29 affected children indicating high degree of genetic heterogeneity and high mortality. Although asparagine depletion is not of diagnostic utility, multiple linear regression model suggested that asparagine levels vary to the extent of 20.6% based on glutamine and aspartate levels and ASNS deficiency results in depletion of asparagine synthesis. ASNS deficiency should be suspected in any neonate with microcephaly and epileptic encephalopathy.


Assuntos
Carbono-Nitrogênio Ligases com Glutamina como Doadora de N-Amida/genética , Deficiências do Desenvolvimento/genética , Microcefalia/genética , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/patologia , Grupo com Ancestrais do Continente Asiático , Carbono-Nitrogênio Ligases com Glutamina como Doadora de N-Amida/deficiência , Pré-Escolar , Consanguinidade , Análise Mutacional de DNA , Deficiências do Desenvolvimento/complicações , Deficiências do Desenvolvimento/patologia , Família , Feminino , Humanos , Índia , Lactente , Recém-Nascido , Hemorragias Intracranianas/congênito , Hemorragias Intracranianas/genética , Masculino , Microcefalia/patologia , Técnicas de Diagnóstico Molecular , Morte Perinatal , Convulsões/complicações , Convulsões/genética
6.
Cell Mol Life Sci ; 76(10): 1935-1945, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30830238

RESUMO

Rab18 is one of the small number of conserved Rab proteins which have been traced to the last eukaryotic common ancestor. It is found in organisms ranging from humans to trypanosomes, and localizes to multiple organelles, including most notably endoplasmic reticulum and lipid droplets. In humans, absence of Rab18 leads to a severe illness known as Warburg-Micro syndrome. Despite this evidence that Rab18 is essential, its role in cells remains mysterious. However, recent studies identifying effectors and interactors of Rab18, are now shedding light on its mechanism of action, suggesting functions related to organelle tethering and to autophagy. In this review, we examine the variety of roles proposed for Rab18 with a focus on new evidence giving insights into the molecular mechanisms it utilizes. Based on this summary of our current understanding, we identify priority areas for further research.


Assuntos
Retículo Endoplasmático/metabolismo , Gotículas Lipídicas/metabolismo , Metabolismo dos Lipídeos , Proteínas rab de Ligação ao GTP/metabolismo , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/metabolismo , Animais , Autofagia/genética , Catarata/congênito , Catarata/genética , Catarata/metabolismo , Córnea/anormalidades , Córnea/metabolismo , Humanos , Hipogonadismo/genética , Hipogonadismo/metabolismo , Deficiência Intelectual/genética , Deficiência Intelectual/metabolismo , Microcefalia/genética , Microcefalia/metabolismo , Modelos Biológicos , Mutação , Atrofia Óptica/genética , Atrofia Óptica/metabolismo , Proteínas rab de Ligação ao GTP/genética
7.
PLoS Genet ; 15(3): e1008050, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30856164

RESUMO

CENP-F is a large, microtubule-binding protein that regulates multiple cellular processes including chromosome segregation and mitochondrial trafficking at cytokinesis. This multiplicity of functions is mediated through the binding of various partners, like Bub1 at the kinetochore and Miro at mitochondria. Due to the multifunctionality of CENP-F, the cellular phenotypes observed upon its depletion are difficult to interpret and there is a need to genetically separate its different functions by preventing binding to selected partners. Here we engineer a CENP-F point-mutant that is deficient in Miro binding and thus is unable to localize to mitochondria, but retains other localizations. We introduce this mutation in cultured human cells using CRISPR/Cas9 system and show it causes a defect in mitochondrial spreading similar to that observed upon Miro depletion. We further create a mouse model carrying this CENP-F variant, as well as truncated CENP-F mutants lacking the farnesylated C-terminus of the protein. Importantly, one of these truncations leads to ~80% downregulation of CENP-F expression. We observe that, despite the phenotypes apparent in cultured cells, mutant mice develop normally. Taken together, these mice will serve as important models to study CENP-F biology at organismal level. In addition, because truncations of CENP-F in humans cause a lethal disease termed Strømme syndrome, they might also be relevant disease models.


Assuntos
Proteínas Cromossômicas não Histona/metabolismo , Proteínas dos Microfilamentos/metabolismo , Proteínas Mitocondriais/metabolismo , Proteínas rho de Ligação ao GTP/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Sistemas CRISPR-Cas , Linhagem Celular , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/genética , Anormalidades do Olho/genética , Humanos , Atresia Intestinal/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Transgênicos , Microcefalia/genética , Proteínas dos Microfilamentos/química , Proteínas dos Microfilamentos/genética , Mitocôndrias/metabolismo , Proteínas Mitocondriais/química , Proteínas Mitocondriais/genética , Mutação Puntual , Prenilação , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas rho de Ligação ao GTP/química , Proteínas rho de Ligação ao GTP/genética
8.
Medicine (Baltimore) ; 98(10): e14780, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30855487

RESUMO

RATIONALE: Holoprosencephaly (HPE) is a severe congenital brain malformation resulting from failed or incomplete forebrain division in early pregnancy. PATIENT CONCERNS: In this study, we reported a 9-month old infant girl with mild microcephaly, semilobor HPE, and arachnoid cyst. DIAGNOSES: Potential genetic defects were screened directly using trio-case whole exome sequencing (WES) rather than traditional karyotype, microarray, and Sanger sequencing of select genes. OUTCOMES: A previous unpublished de novo missense mutation (c.1069C >G, p.H357D) in the 3rd zinc finger domain (ZFD3) of the ZIC2 gene was identified in the affected individual, but not in the parents. Sanger sequencing using specific primers verified the mutation. Extensive bioinformatics analysis confirmed the pathogenicity of this extremely rare mutation. Phenotype-genotype analysis revealed significant correlation between the 3rd zinc-finger domain with semilobor HPE. LESSONS: These findings expanded the spectrum of the ZIC2 gene mutations and associated clinical manifestations, which is the first identification of a mutated ZIC2 gene in a Han infant girl with mild microcephaly, semilobor HPE, and arachnoid cyst.


Assuntos
Cistos Aracnóideos/genética , Holoprosencefalia/genética , Microcefalia/genética , Mutação , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Cistos Aracnóideos/complicações , Cistos Aracnóideos/diagnóstico por imagem , Feminino , Holoprosencefalia/complicações , Holoprosencefalia/diagnóstico por imagem , Humanos , Lactente , Microcefalia/complicações , Microcefalia/diagnóstico por imagem , Proteínas Nucleares/metabolismo , Fenótipo , Fatores de Transcrição/metabolismo , Dedos de Zinco
9.
J Hum Genet ; 64(5): 445-458, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30846821

RESUMO

Seckel syndrome (SS) is a rare spectrum of congenital severe microcephaly and dwarfism. One SS-causative gene is Ataxia Telangiectasia and Rad3-Related Protein (ATR), and ATR (c.2101 A>G) mutation causes skipping of exon 9, resulting in a hypomorphic ATR defect. This mutation is considered the cause of an impaired response to DNA replication stress, the main function of ATR, contributing to the pathogenesis of microcephaly. However, the precise behavior and impact of this splicing defect in human neural progenitor cells (NPCs) is unclear. To address this, we established induced pluripotent stem cells (iPSCs) from fibroblasts carrying the ATR mutation and an isogenic ATR-corrected counterpart iPSC clone. SS-patient-derived iPSCs (SS-iPSCs) exhibited cell type-specific splicing; exon 9 was dominantly skipped in fibroblasts and iPSC-derived NPCs, but it was included in undifferentiated iPSCs and definitive endodermal cells. SS-iPSC-derived NPCs (SS-NPCs) showed distinct expression profiles from ATR non-mutated NPCs with negative enrichment of neuronal genesis-related gene sets. In SS-NPCs, abnormal mitotic spindles occurred more frequently than in gene-corrected counterparts, and the alignment of NPCs in the surface of the neurospheres was perturbed. Finally, we tested several splicing-modifying compounds and found that TG003, a CLK1 inhibitor, could pharmacologically rescue the exon 9 skipping in SS-NPCs. Treatment with TG003 restored the ATR kinase activity in SS-NPCs and decreased the frequency of abnormal mitotic events. In conclusion, our iPSC model revealed a novel effect of the ATR mutation in mitotic processes of NPCs and NPC-specific missplicing, accompanied by the recovery of neuronal defects using a splicing rectifier.


Assuntos
Processamento Alternativo , Proteínas Mutadas de Ataxia Telangiectasia , Nanismo , Facies , Células-Tronco Pluripotentes Induzidas , Microcefalia , Modelos Biológicos , Mutação , Proteínas Mutadas de Ataxia Telangiectasia/biossíntese , Proteínas Mutadas de Ataxia Telangiectasia/genética , Linhagem Celular , Nanismo/enzimologia , Nanismo/genética , Nanismo/patologia , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/enzimologia , Células-Tronco Pluripotentes Induzidas/patologia , Masculino , Microcefalia/enzimologia , Microcefalia/genética , Microcefalia/patologia
10.
J Appl Genet ; 60(2): 151-162, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30706430

RESUMO

Autosomal recessive primary microcephaly (MCPH) is a group of rare neurodevelopmental diseases with severe microcephaly at birth. One type of the disorder, MCPH2, is caused by biallelic mutations in the WDR62 gene, which encodes the WD repeat-containing protein 62. Patients with WDR62 mutation may have a wide range of malformations of cortical development in addition to congenital microcephaly. We describe two patients, a boy and a girl, with severe congenital microcephaly, global developmental delay, epilepsy, and failure to thrive. MRI showed hemispherical asymmetry, diffuse pachygyria, thick gray matter, indistinct gray-white matter junction, and corpus callosum and white matter hypoplasia. Whole exome sequencing revealed the same novel homozygous missense mutation, c.668T>C, p.Phe223Ser in exon 6 of the WDR62 gene. The healthy parents were heterozygous for this mutation. The mutation affects a highly conserved region in one of the WD repeats of the WDR62 protein. Haplotype analysis showed genetic relatedness between the families of the patients. Our findings expand the spectrum of mutations randomly distributed in the WDR62 gene. A review is also provided of the brain malformations described in WDR62 mutations in association with congenital microcephaly.


Assuntos
Deficiências do Desenvolvimento/genética , Microcefalia/genética , Proteínas do Tecido Nervoso/genética , Deficiências do Desenvolvimento/diagnóstico por imagem , Deficiências do Desenvolvimento/fisiopatologia , Feminino , Substância Cinzenta/diagnóstico por imagem , Substância Cinzenta/patologia , Haplótipos , Homozigoto , Humanos , Masculino , Microcefalia/diagnóstico por imagem , Microcefalia/fisiopatologia , Mutação de Sentido Incorreto/genética , Linhagem , Substância Branca/diagnóstico por imagem , Substância Branca/patologia
11.
Hum Genet ; 138(3): 221-229, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30758658

RESUMO

Nuclear pore complex (NPC) is a fundamental component of the nuclear envelope and is key to the nucleocytoplasmic transport. Mutations in several NUP genes that encode individual components of NPC known as nucleoporins have been identified in recent years among patients with static encephalopathies characterized by developmental delay and microcephaly. We describe a multiplex consanguineous family in which four affected members presented with severe neonatal hypotonia, profound global developmental delay, progressive microcephaly and early death. Autozygome and linkage analysis revealed that this phenotype is linked to a founder disease haplotype (chr9:127,113,732-135,288,807) in which whole exome sequencing revealed the presence of a novel homozygous missense variant in NUP214. Functional analysis of patient-derived fibroblasts recapitulated the dysmorphic phenotype of nuclei that was previously described in NUP214 knockdown cells. In addition, the typical rim staining of NUP214 is largely displaced, further supporting the deleterious effect of the variant. Our data expand the list of NUP genes that are mutated in encephalopathy disorders in humans.


Assuntos
Encefalopatias/diagnóstico , Encefalopatias/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Microcefalia/diagnóstico , Microcefalia/genética , Complexo de Proteínas Formadoras de Poros Nucleares/deficiência , Sequência de Aminoácidos , Consanguinidade , Feminino , Genes Recessivos , Ligação Genética , Homozigoto , Humanos , Lactente , Mutação , Linhagem , Fenótipo , Índice de Gravidade de Doença , Sequenciamento Completo do Exoma
12.
Hum Genet ; 138(3): 231-239, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30778726

RESUMO

Pseudouridylation is the most common post-transcriptional modification, wherein uridine is isomerized into 5-ribosyluracil (pseudouridine, Ψ). The resulting increase in base stacking and creation of additional hydrogen bonds are thought to enhance RNA stability. Pseudouridine synthases are encoded in humans by 13 genes, two of which are linked to Mendelian diseases: PUS1 and PUS3. Very recently, PUS7 mutations were reported to cause intellectual disability with growth retardation. We describe two families in which two different homozygous PUS7 mutations (missense and frameshift deletion) segregate with a phenotype comprising intellectual disability and progressive microcephaly. Short stature and hearing loss were variable in these patients. Functional characterization of the two mutations confirmed that both result in decreased levels of Ψ13 in tRNAs. Furthermore, the missense variant of the S. cerevisiae ortholog failed to complement the growth defect of S. cerevisiae pus7Δ trm8Δ mutants. Our results confirm that PUS7 is a bona fide Mendelian disease gene and expand the list of human diseases caused by impaired pseudouridylation.


Assuntos
Estudos de Associação Genética , Predisposição Genética para Doença , Deficiência Intelectual/genética , Microcefalia/genética , Mutação , Pseudouridina/genética , Adolescente , Sequência de Aminoácidos , Criança , Mapeamento Cromossômico , Consanguinidade , Feminino , Genes Recessivos , Humanos , Masculino , Microcefalia/diagnóstico , Linhagem , Fenótipo , RNA de Transferência/genética , Sequenciamento Completo do Exoma
13.
Gene ; 695: 12-17, 2019 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-30738969

RESUMO

Microcephaly is a rare condition in which the occipitofrontal circumference in a child is more than two standard deviations below the mean of children of the same age and gender. It is mainly caused by genetic abnormalities that interfere with the growth of the cerebral cortex during early months of fetal development. We present a case of a 12 years old patient with microcephaly. To identify a possible genetic origin of the phenotype, we performed array CGH and exome sequencing in the patient. Exome sequencing revealed the presence of a de novo missense mutation in the TUBB5 gene (E401K). Mutations in the TUBB5 are mainly responsible for microcephaly but the clinical spectrum is wide, from patients with severe developmental delay, and the presence of different brain malformations, to patients with only slightly cognitive impairment and normal motor development. Our patient shows a milder phenotype than other patients carrying the same mutation. These differences in the clinical features suggest that other factors, presumably genetic or epigenetic, could be modulating clinical expressivity of TUBB5. It is therefore evident that more functional studies are needed to understand the pathology that underlies the clinical spectrum of tubulin associated disease states.


Assuntos
Deficiências do Desenvolvimento/genética , Microcefalia/genética , Malformações do Sistema Nervoso/genética , Tubulina (Proteína)/genética , Criança , Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/fisiopatologia , Exoma/genética , Feminino , Humanos , Masculino , Microcefalia/diagnóstico , Microcefalia/fisiopatologia , Mutação , Malformações do Sistema Nervoso/diagnóstico , Malformações do Sistema Nervoso/fisiopatologia
14.
Proc Natl Acad Sci U S A ; 116(9): 3662-3667, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30808755

RESUMO

Kaufman oculocerebrofacial syndrome (KOS) is a recessive neurodevelopmental disorder characterized by intellectual disability and lack of speech. KOS is caused by inactivating mutations in UBE3B, but the underlying biological mechanisms are completely unknown. We found that loss of Ube3b in mice resulted in growth retardation, decreased grip strength, and loss of vocalization. The brains of Ube3b -/- mice had hypoplasia of the corpus callosum, enlarged ventricles, and decreased thickness of the somatosensory cortex. Ube3b -/- cortical neurons had abnormal dendritic morphology and synapses. We identified 22 UBE3B interactors and found that branched-chain α-ketoacid dehydrogenase kinase (BCKDK) is an in vivo UBE3B substrate. Since BCKDK targets several metabolic pathways, we profiled plasma and cortical metabolomes from Ube3b -/- mice. Nucleotide metabolism and the tricarboxylic acid cycle were among the pathways perturbed. Substrate-induced mitochondrial respiration was reduced in skeletal muscle but not in liver of Ube3b -/- mice. To assess the relevance of these findings to humans, we identified three KOS patients who had compound heterozygous UBE3B mutations. We discovered changes in metabolites from similar pathways in plasma from these patients. Collectively, our results implicate a disease mechanism in KOS, suggest that it is a metabolic encephalomyopathy, and provide an entry to targeted therapies.


Assuntos
Anormalidades do Olho/genética , Deficiência Intelectual/genética , Transtornos do Desenvolvimento da Linguagem/genética , Deformidades Congênitas dos Membros/genética , Microcefalia/genética , Proteínas Quinases/genética , Ubiquitina-Proteína Ligases/genética , Adolescente , Adulto , Animais , Encéfalo/fisiopatologia , Criança , Anormalidades do Olho/fisiopatologia , Facies , Humanos , Deficiência Intelectual/fisiopatologia , Transtornos do Desenvolvimento da Linguagem/fisiopatologia , Deformidades Congênitas dos Membros/fisiopatologia , Masculino , Redes e Vias Metabólicas , Camundongos , Camundongos Knockout , Microcefalia/fisiopatologia , Mutação , Fenótipo , Ubiquitina/genética
15.
Nat Commun ; 10(1): 707, 2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30755602

RESUMO

Aminoacyl-tRNA synthetases (ARSs) function to transfer amino acids to cognate tRNA molecules, which are required for protein translation. To date, biallelic mutations in 31 ARS genes are known to cause recessive, early-onset severe multi-organ diseases. VARS encodes the only known valine cytoplasmic-localized aminoacyl-tRNA synthetase. Here, we report seven patients from five unrelated families with five different biallelic missense variants in VARS. Subjects present with a range of global developmental delay, epileptic encephalopathy and primary or progressive microcephaly. Longitudinal assessment demonstrates progressive cortical atrophy and white matter volume loss. Variants map to the VARS tRNA binding domain and adjacent to the anticodon domain, and disrupt highly conserved residues. Patient primary cells show intact VARS protein but reduced enzymatic activity, suggesting partial loss of function. The implication of VARS in pediatric neurodegeneration broadens the spectrum of human diseases due to mutations in tRNA synthetase genes.


Assuntos
Epilepsia/genética , Mutação , Valina-tRNA Ligase/genética , Alelos , Anticódon , Criança , Pré-Escolar , Progressão da Doença , Epilepsia/enzimologia , Epilepsia/patologia , Feminino , Predisposição Genética para Doença , Humanos , Estudos Longitudinais , Mutação com Perda de Função , Masculino , Microcefalia/enzimologia , Microcefalia/genética , Modelos Moleculares , Transtornos do Neurodesenvolvimento/enzimologia , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/patologia , Linhagem , Biossíntese de Proteínas , Domínios e Motivos de Interação entre Proteínas , RNA de Transferência/genética , Sequenciamento Completo do Exoma , Sequenciamento Completo do Genoma
16.
Orphanet J Rare Dis ; 14(1): 38, 2019 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-30744660

RESUMO

BACKGROUND: The TUBA1A-associated tubulinopathy is clinically heterogeneous with brain malformations, microcephaly, developmental delay and epilepsy being the main clinical features. It is an autosomal dominant disorder mostly caused by de novo variants in TUBA1A. RESULTS: In three individuals with developmental delay we identified heterozygous de novo missense variants in TUBA1A using exome sequencing. While the c.1307G > A, p.(Gly436Asp) variant was novel, the two variants c.518C > T, p.(Pro173Leu) and c.641G > A, p.(Arg214His) were previously described. We compared the variable phenotype observed in these individuals with a carefully conducted review of the current literature and identified 166 individuals, 146 born and 20 fetuses with a TUBA1A variant. In 107 cases with available clinical information we standardized the reported phenotypes according to the Human Phenotype Ontology. The most commonly reported features were developmental delay (98%), anomalies of the corpus callosum (96%), microcephaly (76%) and lissencephaly (agyria-pachygyria) (70%), although reporting was incomplete in the different studies. We identified a total of 121 specific variants, including 15 recurrent ones. Missense variants cluster in the C-terminal region around the most commonly affected amino acid position Arg402 (13.3%). In a three-dimensional protein model, 38.6% of all disease-causing variants including those in the C-terminal region are predicted to affect the binding of microtubule-associated proteins or motor proteins. Genotype-phenotype analysis for recurrent variants showed an overrepresentation of certain clinical features. However, individuals with these variants are often reported in the same publication. CONCLUSIONS: With 166 individuals, we present the most comprehensive phenotypic and genotypic standardized synopsis for clinical interpretation of TUBA1A variants. Despite this considerable number, a detailed genotype-phenotype characterization is limited by large inter-study variability in reporting.


Assuntos
Tubulina (Proteína)/genética , Adolescente , Criança , Corpo Caloso/metabolismo , Corpo Caloso/patologia , Feminino , Genótipo , Humanos , Lisencefalia/genética , Lisencefalia/patologia , Masculino , Microcefalia/genética , Microcefalia/patologia , Mutação de Sentido Incorreto/genética , Fenótipo
17.
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
18.
Hum Genet ; 138(2): 187-198, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30656450

RESUMO

Developmental and epileptic encephalopathies (DEEs) are genetically heterogenous conditions, often characterized by early onset, EEG interictal epileptiform abnormalities, polymorphous and drug-resistant seizures, and neurodevelopmental impairments. In this study, we investigated the genetic defects in two siblings who presented with severe DEE, microcephaly, spastic tetraplegia, diffuse brain hypomyelination, cerebellar atrophy, short stature, and kyphoscoliosis. Whole exome next-generation sequencing (WES) identified in both siblings a homozygous non-sense variant in the ACTL6B gene (NM_016188:c.820C>T;p.Gln274*) coding for a subunit of the neuron-specific chromatin remodeling complex nBAF. To further support these findings, a targeted ACTL6B sequencing assay was performed on a cohort of 85 unrelated DEE individuals, leading to the identification of a homozygous missense variant (NM_016188:c.1045G>A;p.Gly349Ser) in a patient. This variant did not segregate in the unaffected siblings in this family and was classified as deleterious by several prediction softwares. Interestingly, in both families, homozygous patients shared a rather homogeneous phenotype. Very few patients with ACTL6B gene variants have been sporadically reported in WES cohort studies of patients with neurodevelopmental disorders and/or congenital brain malformations. However, the limited number of patients with incomplete clinical information yet reported in the literature did not allow to establish a strong gene-disease association. Here, we provide additional genetic and clinical data on three new cases that support the pathogenic role of ACTL6B gene mutation in a syndromic form of DEE.


Assuntos
Actinas/genética , Montagem e Desmontagem da Cromatina , Proteínas Cromossômicas não Histona/genética , Proteínas de Ligação a DNA/genética , Doenças Genéticas Inatas/diagnóstico por imagem , Microcefalia/genética , Transtornos do Neurodesenvolvimento/genética , Quadriplegia/genética , Espasmos Infantis/genética , Criança , Pré-Escolar , Cromatina/genética , Metilação de DNA/genética , Feminino , Doenças Genéticas Inatas/genética , Humanos , Lactente , Recém-Nascido , Masculino , Microcefalia/diagnóstico por imagem , Transtornos do Neurodesenvolvimento/diagnóstico por imagem , Linhagem , Quadriplegia/diagnóstico por imagem , Espasmos Infantis/diagnóstico por imagem
19.
Clin Chim Acta ; 491: 15-18, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30639237

RESUMO

Primary autosomal recessive microcephaly (MCPH) is a rare hereditary disease characterized by congenitally small with brain circumference of the head below 3 standard deviations (SD). By far, 18 MCPH genes have been reported to be associated with the disease. SASS6 gene functioned in assembly of centrioles that the majority of MCPH genes present at the centrosome. There was only research reporting a homozygous missense mutation in SASS6 gene detected in a consanguineous Pakistani family. By conducting Whole-exome sequencing (WES) and Sanger sequencing on the family trio, we identified two novel splice site mutations c.127-13A>G and c.1867+2T>A in compound heterozygous hereditary form in the SASS6 gene. The two mutations were confirmed to alter mRNA splicing by RT-PCR assay. Our finding supported the role of SASS6 in the pathogenesis of microcephaly, expanding mutation spectrums and contributing to understanding of molecular mechanisms of MCPH.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Proteínas de Ciclo Celular/genética , Heterozigoto , Microcefalia/genética , Mutação , Linhagem , Adulto , Sequência de Bases , Feminino , Humanos , Masculino , Sítios de Splice de RNA/genética
20.
Psychiatr Genet ; 29(2): 57-60, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30531648

RESUMO

Schizophrenia is a genetically complex disease that is related to neurodevelopmental abnormalities. Several genetic polymorphisms and genetic syndromes associated with neurodevelopmental processes have been linked to schizophrenia. In this case report, we present a case with an association between microcephalic osteodysplastic primordial dwarfism type II and schizophrenia. Microcephalic osteodysplastic primordial dwarfism type II syndrome is a rare, autosomal recessive disease that occurs as a result of the mutations in the pericentrin (PCNT) gene that are responsible for cell cycle and division. In this report, we discuss the possible association between the PCNT gene and schizophrenia.


Assuntos
Antígenos/genética , Nanismo/genética , Retardo do Crescimento Fetal/genética , Microcefalia/genética , Osteocondrodisplasias/genética , Esquizofrenia/genética , Adulto , Nanismo/complicações , Feminino , Humanos , Microcefalia/complicações , Mutação , Osteocondrodisplasias/complicações , Síndrome
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