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1.
Clin Genet ; 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33415748

RESUMO

Megalencephaly-CApillary malformation-Polymicrogyria (MCAP) syndrome results from somatic mosaic gain-of-function variants in PIK3CA. Main features are macrocephaly, somatic overgrowth, cutaneous vascular malformations, connective tissue dysplasia, neurodevelopmental delay, and brain anomalies. The objectives of this study were to describe the clinical and radiological features of MCAP, to suggest relevant clinical endpoints applicable in future trials of targeted drug therapy. Based on a French collaboration, we collected clinical features of 33 patients (21 females, 12 males, median age of 9.9 years) with MCAP carrying mosaic PIK3CA pathogenic variants. MRI images were reviewed for 21 patients. The main clinical features reported were macrocephaly at birth (20/31), postnatal macrocephaly (31/32), body/facial asymmetry (21/33), cutaneous capillary malformations (naevus flammeus 28/33, cutis marmorata 17/33). Intellectual disability was present in 15 patients. Among the MRI images reviewed, the neuroimaging findings were megalencephaly (20/21), thickening of corpus callosum (16/21), Chiari malformation (12/21), ventriculomegaly/hydrocephaly (10/21), cerebral asymmetry (6/21) and polymicrogyria (2/21). This study confirms the main known clinical features that defines MCAP syndrome. Taking into account the phenotypic heterogeneity in MCAP patients, in the context of emerging clinical trials, we suggest that patients should be evaluated based on the main neurocognitive expression on each patient.

2.
Genet Med ; 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33299146

RESUMO

PURPOSE: This study aimsed to provide a comprehensive description of the phenotypic and genotypic spectrum of SNAP25 developmental and epileptic encephalopathy (SNAP25-DEE) by reviewing newly identified and previously reported individuals. METHODS: Individuals harboring heterozygous missense or loss-of-function variants in SNAP25 were assembled through collaboration with international colleagues, matchmaking platforms, and literature review. For each individual, detailed phenotyping, classification, and structural modeling of the identified variant were performed. RESULTS: The cohort comprises 23 individuals with pathogenic or likely pathogenic de novo variants in SNAP25. Intellectual disability and early-onset epilepsy were identified as the core symptoms of SNAP25-DEE, with recurrent findings of movement disorders, cerebral visual impairment, and brain atrophy. Structural modeling for all variants predicted possible functional defects concerning SNAP25 or impaired interaction with other components of the SNARE complex. CONCLUSION: We provide a comprehensive description of SNAP25-DEE with intellectual disability and early-onset epilepsy mostly occurring before the age of two years. These core symptoms and additional recurrent phenotypes show an overlap to genes encoding other components or associated proteins of the SNARE complex such as STX1B, STXBP1, or VAMP2. Thus, these findings advance the concept of a group of neurodevelopmental disorders that may be termed "SNAREopathies."

3.
Neurol Genet ; 6(6): e520, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33134516

RESUMO

Objective: To delineate the phenotype associated with biallelic ATAD1 variants. Methods: We describe 2 new patients with ATAD1-related disorder diagnosed by whole-exome sequencing and compare their phenotype to 6 previous patients. Results: Patients 1 and 2 had a similar distinctive phenotype comprising congenital stiffness of limbs, absent spontaneous movements, weak sucking, and hypoventilation. Both had absent brainstem evoked auditory responses (BEARs). Patient 1 carried the homozygous p.(His357Argfs*15) variant in ATAD1. In the light of the finding in patient 1, a second reading of exome data for patient 2 revealed the novel homozygous p.(Gly128Val) variant. Conclusions: Analysis of the phenotypes of these 2 patients and of the 6 previous cases showed that biallelic ATAD1 mutations are responsible for a unique congenital encephalopathy likely comprising absent BEAR, different from hyperekplexia and other conditions with neonatal hypertonia.

4.
Am J Hum Genet ; 107(6): 1096-1112, 2020 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-33232675

RESUMO

SWI/SNF-related intellectual disability disorders (SSRIDDs) are rare neurodevelopmental disorders characterized by developmental disability, coarse facial features, and fifth digit/nail hypoplasia that are caused by pathogenic variants in genes that encode for members of the SWI/SNF (or BAF) family of chromatin remodeling complexes. We have identified 12 individuals with rare variants (10 loss-of-function, 2 missense) in the BICRA (BRD4 interacting chromatin remodeling complex-associated protein) gene, also known as GLTSCR1, which encodes a subunit of the non-canonical BAF (ncBAF) complex. These individuals exhibited neurodevelopmental phenotypes that include developmental delay, intellectual disability, autism spectrum disorder, and behavioral abnormalities as well as dysmorphic features. Notably, the majority of individuals lack the fifth digit/nail hypoplasia phenotype, a hallmark of most SSRIDDs. To confirm the role of BICRA in the development of these phenotypes, we performed functional characterization of the zebrafish and Drosophila orthologs of BICRA. In zebrafish, a mutation of bicra that mimics one of the loss-of-function variants leads to craniofacial defects possibly akin to the dysmorphic facial features seen in individuals harboring putatively pathogenic BICRA variants. We further show that Bicra physically binds to other non-canonical ncBAF complex members, including the BRD9/7 ortholog, CG7154, and is the defining member of the ncBAF complex in flies. Like other SWI/SNF complex members, loss of Bicra function in flies acts as a dominant enhancer of position effect variegation but in a more context-specific manner. We conclude that haploinsufficiency of BICRA leads to a unique SSRIDD in humans whose phenotypes overlap with those previously reported.

5.
J Intern Med ; 2020 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-33107650

RESUMO

PURPOSE: Pseudoxanthoma elasticum (PXE) is a recessive disorder involving skin, eyes and arteries, mainly caused by ABCC6 pathogenic variants. However, almost one fifth of patients remain genetically unsolved despite extensive genetic screening of ABCC6, as illustrated in a large French PXE series of 220 cases. We searched for new PXE gene(s) to solve the ABCC6-negative patients. METHODS: First, family-based exome sequencing was performed, in one ABCC6-negative PXE patient with additional neurological features, and her relatives. CYP2U1, involved in hereditary spastic paraplegia type 56 (SPG56), was selected based on this complex phenotype, and the presence of two candidate variants. Second, CYP2U1 sequencing was performed in a retrospective series of 46 additional ABCC6-negative PXE probands. Third, six additional SPG56 patients were evaluated for PXE skin and eye phenotype. Additionally, plasma pyrophosphate dosage and functional analyses were performed in some of these patients. RESULTS: 6.4% of ABCC6-negative PXE patients (n=3) harbored biallelic pathogenic variants in CYP2U1. PXE skin lesions with histological confirmation, eye lesions including maculopathy or angioid streaks, and various neurological symptoms were present. CYP2U1 missense variants were confirmed to impair protein function. Plasma pyrophosphate levels were normal. Two SPG56 patients (33%) presented some phenotypic overlap with PXE. CONCLUSION: CYP2U1 pathogenic variants are found in unsolved PXE patients with neurological findings, including spastic paraplegia, expanding the SPG56 phenotype and highlighting its overlap with PXE. The pathophysiology of ABCC6 and CYP2U1 should be explored to explain their respective role and potential interaction in ectopic mineralization.

6.
Epilepsia ; 61(11): 2461-2473, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32954514

RESUMO

OBJECTIVE: We aimed to delineate the phenotypic spectrum and long-term outcome of individuals with KCNB1 encephalopathy. METHODS: We collected genetic, clinical, electroencephalographic, and imaging data of individuals with KCNB1 pathogenic variants recruited through an international collaboration, with the support of the family association "KCNB1 France." Patients were classified as having developmental and epileptic encephalopathy (DEE) or developmental encephalopathy (DE). In addition, we reviewed published cases and provided the long-term outcome in patients older than 12 years from our series and from literature. RESULTS: Our series included 36 patients (21 males, median age = 10 years, range = 1.6 months-34 years). Twenty patients (56%) had DEE with infantile onset seizures (seizure onset = 10 months, range = 10 days-3.5 years), whereas 16 (33%) had DE with late onset epilepsy in 10 (seizure onset = 5 years, range = 18 months-25 years) and without epilepsy in six. Cognitive impairment was more severe in individuals with DEE compared to those with DE. Analysis of 73 individuals with KCNB1 pathogenic variants (36 from our series and 37 published individuals in nine reports) showed developmental delay in all with severe to profound intellectual disability in 67% (n = 41/61) and autistic features in 56% (n = 32/57). Long-term outcome in 22 individuals older than 12 years (14 in our series and eight published individuals) showed poor cognitive, psychiatric, and behavioral outcome. Epilepsy course was variable. Missense variants were associated with more frequent and more severe epilepsy compared to truncating variants. SIGNIFICANCE: Our study describes the phenotypic spectrum of KCNB1 encephalopathy, which varies from severe DEE to DE with or without epilepsy. Although cognitive impairment is worse in patients with DEE, long-term outcome is poor for most and missense variants are associated with more severe epilepsy outcome. Further understanding of disease mechanisms should facilitate the development of targeted therapies, much needed to improve the neurodevelopmental prognosis.

7.
Genet Med ; 22(11): 1887-1891, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32565546

RESUMO

PURPOSE: Abnormality of the corpus callosum (AbnCC) is etiologically a heterogeneous condition and the prognosis in prenatally diagnosed cases is difficult to predict. The purpose of our research was to establish the diagnostic yield using chromosomal microarray (CMA) and exome sequencing (ES) in cases with prenatally diagnosed isolated (iAbnCC) and nonisolated AbnCC (niAbnCC). METHODS: CMA and prenatal trio ES (pES) were done on 65 fetuses with iAbnCC and niAbnCC. Only pathogenic gene variants known to be associated with AbnCC and/or intellectual disability were considered. RESULTS: pES results were available within a median of 21.5 days (9-53 days). A pathogenic single-nucleotide variant (SNV) was identified in 12 cases (18%) and a pathogenic CNV was identified in 3 cases (4.5%). Thus, the genetic etiology was determined in 23% of cases. In all diagnosed cases, the results provided sufficient information regarding the neurodevelopmental prognosis and helped the parents to make an informed decision regarding the outcome of the pregnancy. CONCLUSION: Our results show the significant diagnostic and prognostic contribution of CMA and pES in cases with prenatally diagnosed AbnCC. Further prospective cohort studies with long-term follow-up of the born children will be needed to provide accurate prenatal counseling after a negative pES result.

8.
Epilepsia ; 61(6): 1142-1155, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32452540

RESUMO

OBJECTIVE: To define the phenotypic spectrum of phosphatidylinositol glycan class A protein (PIGA)-related congenital disorder of glycosylation (PIGA-CDG) and evaluate genotype-phenotype correlations. METHODS: Our cohort encompasses 40 affected males with a pathogenic PIGA variant. We performed a detailed phenotypic assessment, and in addition, we reviewed the available clinical data of 36 previously published cases and assessed the variant pathogenicity using bioinformatical approaches. RESULTS: Most individuals had hypotonia, moderate to profound global developmental delay, and intractable seizures. We found that PIGA-CDG spans from a pure neurological phenotype at the mild end to a Fryns syndrome-like phenotype. We found a high frequency of cardiac anomalies including structural anomalies and cardiomyopathy, and a high frequency of spontaneous death, especially in childhood. Comparative bioinformatical analysis of common variants, found in the healthy population, and pathogenic variants, identified in affected individuals, revealed a profound physiochemical dissimilarity of the substituted amino acids in variant constrained regions of the protein. SIGNIFICANCE: Our comprehensive analysis of the largest cohort of published and novel PIGA patients broadens the spectrum of PIGA-CDG. Our genotype-phenotype correlation facilitates the estimation on pathogenicity of variants with unknown clinical significance and prognosis for individuals with pathogenic variants in PIGA.


Assuntos
Variação Genética/genética , Hérnia Diafragmática/diagnóstico por imagem , Hérnia Diafragmática/genética , Deformidades Congênitas dos Membros/diagnóstico por imagem , Deformidades Congênitas dos Membros/genética , Proteínas de Membrana/genética , Adulto , Sequência de Aminoácidos , Criança , Estudos de Coortes , Eletroencefalografia/métodos , Facies , Hérnia Diafragmática/fisiopatologia , Humanos , Recém-Nascido , Deformidades Congênitas dos Membros/fisiopatologia , Imagem por Ressonância Magnética/métodos , Masculino
9.
Eur J Hum Genet ; 28(10): 1403-1413, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32467598

RESUMO

Cause of complex dyskinesia remains elusive in some patients. A homozygous missense variant leading to drastic decrease of PDE2A enzymatic activity was reported in one patient with childhood-onset choreodystonia preceded by paroxysmal dyskinesia and associated with cognitive impairment and interictal EEG abnormalities. Here, we report three new cases with biallelic PDE2A variants identified by trio whole-exome sequencing. Mitochondria network was analyzed after Mitotracker™ Red staining in control and mutated primary fibroblasts. Analysis of retrospective video of patients' movement disorder and refinement of phenotype was carried out. We identified a homozygous gain of stop codon variant c.1180C>T; p.(Gln394*) in PDE2A in siblings and compound heterozygous variants in young adult: a missense c.446C>T; p.(Pro149Leu) and splice-site variant c.1922+5G>A predicted and shown to produce an out of frame transcript lacking exon 22. All three patients had cognitive impairment or developmental delay. The phenotype of the two oldest patients, aged 9 and 26, was characterized by childhood-onset refractory paroxysmal dyskinesia initially misdiagnosed as epilepsy due to interictal EEG abnormalities. The youngest patient showed a proven epilepsy at the age of 4 months and no paroxysmal dyskinesia at 15 months. Interestingly, analysis of the fibroblasts with the biallelic variants in PDE2A variants revealed mitochondria network morphology changes. Together with previously reported case, our three patients confirm that biallelic PDE2A variants are a cause of childhood-onset refractory paroxysmal dyskinesia with cognitive impairment, sometimes associated with choreodystonia and interictal baseline EEG abnormalities or epilepsy.

10.
Nat Commun ; 11(1): 2441, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415109

RESUMO

KIF21B is a kinesin protein that promotes intracellular transport and controls microtubule dynamics. We report three missense variants and one duplication in KIF21B in individuals with neurodevelopmental disorders associated with brain malformations, including corpus callosum agenesis (ACC) and microcephaly. We demonstrate, in vivo, that the expression of KIF21B missense variants specifically recapitulates patients' neurodevelopmental abnormalities, including microcephaly and reduced intra- and inter-hemispheric connectivity. We establish that missense KIF21B variants impede neuronal migration through attenuation of kinesin autoinhibition leading to aberrant KIF21B motility activity. We also show that the ACC-related KIF21B variant independently perturbs axonal growth and ipsilateral axon branching through two distinct mechanisms, both leading to deregulation of canonical kinesin motor activity. The duplication introduces a premature termination codon leading to nonsense-mediated mRNA decay. Although we demonstrate that Kif21b haploinsufficiency leads to an impaired neuronal positioning, the duplication variant might not be pathogenic. Altogether, our data indicate that impaired KIF21B autoregulation and function play a critical role in the pathogenicity of human neurodevelopmental disorder.


Assuntos
Cinesina/genética , Atividade Motora , Mutação/genética , Transtornos do Neurodesenvolvimento/genética , Transtornos do Neurodesenvolvimento/fisiopatologia , Animais , Axônios/metabolismo , Movimento Celular , Proliferação de Células , Córtex Cerebral/embriologia , Córtex Cerebral/patologia , Córtex Cerebral/fisiopatologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Células HEK293 , Humanos , Masculino , Camundongos , Mutação de Sentido Incorreto/genética , Rede Nervosa/patologia , Rede Nervosa/fisiopatologia , Neurônios/metabolismo , Tamanho do Órgão , Organogênese/genética , Linhagem , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Peixe-Zebra/anatomia & histologia , Peixe-Zebra/genética
11.
J Med Genet ; 57(7): 466-474, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32277047

RESUMO

PURPOSE: Marfanoid habitus (MH) combined with intellectual disability (ID) (MHID) is a clinically and genetically heterogeneous presentation. The combination of array CGH and targeted sequencing of genes responsible for Marfan or Lujan-Fryns syndrome explain no more than 20% of subjects. METHODS: To further decipher the genetic basis of MHID, we performed exome sequencing on a combination of trio-based (33 subjects) or single probands (31 subjects), of which 61 were sporadic. RESULTS: We identified eight genes with de novo variants (DNVs) in at least two unrelated individuals (ARID1B, ATP1A1, DLG4, EHMT1, NFIX, NSD1, NUP205 and ZEB2). Using simulation models, we showed that five genes (DLG4, NFIX, EHMT1, ZEB2 and ATP1A1) met conservative Bonferroni genomewide significance for an excess of the observed de novo point variants. Overall, at least one pathogenic or likely pathogenic variant was identified in 54.7% of subjects (35/64). These variants fell within 27 genes previously associated with Mendelian disorders, including NSD1 and NFIX, which are known to be mutated in overgrowth syndromes. CONCLUSION: We demonstrated that DNVs were enriched in chromatin remodelling (p=2×10-4) and genes regulated by the fragile X mental retardation protein (p=3×10-8), highlighting overlapping genetic mechanisms between MHID and related neurodevelopmental disorders.

12.
Parkinsonism Relat Disord ; 74: 50-56, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32334381

RESUMO

INTRODUCTION: A strategy based on targeted gene panel sequencing identifies possibly pathogenic variants in fewer than 20% of cases in early-onset and familial form of dystonia. By using Whole Exome Sequencing (WES), we aimed to identify the missing genetic causes in dystonic patients without diagnosis despite gene panel sequencing. MATERIAL AND METHODS: WES was applied to DNA samples from 32 patients with early-onset or familial dystonia investigated by sequencing of a 127 movement disorders-associated gene panel. Dystonia was described according to the familial history, body distribution, evolution pattern, age of onset, associated symptoms and associated movement disorders. Rate of diagnoses was evaluated for each clinical feature. RESULTS: We identified causative variants for 11 patients from 9 families in CTNNB1, SUCLG1, NUS1, CNTNAP1, KCNB1, RELN, GNAO1, HIBCH, ADCK3 genes, yielding an overall diagnostic rate of 34.4%. Diagnostic yield was higher in complex dystonia compared to non-complex dystonia (66.7%-5.9%; p < 0.002), especially in patients showing intellectual disability compared to the patients without intellectual disability (87.5%-16.7%; p < 0.002). CONCLUSION: Our approach suggests WES as an efficient tool to improve the diagnostic yield after gene panel sequencing in dystonia. Larger study are warranted to confirm a potential genetic overlap between neurodevelopmental diseases and dystonia.

13.
Clin Neurophysiol ; 131(5): 1030-1039, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32197126

RESUMO

OBJECTIVE: To investigate the clinical and EEG features of Encephalopathy with Status Epilepticus during slow Sleep (ESES) related to CNKSR2 pathogenic variants. METHODS: Detailed clinical history, repeated wakefulness/overnight sleep EEGs, brain MRI were collected in five patients, including one female, with CNKSR2-related ESES. RESULTS: Neurodevelopment in infancy was normal in two patients, delayed in three. Epilepsy onset (age range: 2-6 years) was associated with appearance or aggravation of cognitive impairment, language regression and/or behavioral disorders. Worsening of epilepsy and of cognitive/behavioral disturbances paralleled by enhancement of non-rapid eye movement (NREM) sleep-related, frontally predominant, EEG epileptic discharges [spike-wave-index (SWI): range 60-96%] was consistent with ESES. In three patients, episodes of absence status epilepticus or aggravation of atypical absences occurred, in this latter case associated with striking increment of awake SWI. Speech/oro-motor dyspraxia was diagnosed in four patients. In two patients, long-term follow-up showed epilepsy remission and persistence of mild/moderate cognitive disorders and behavioral disturbances into adulthood. CONCLUSIONS: Novel findings of our study are occurrence also in females, normal neurodevelopment before epilepsy onset, epilepsy aggravation associated with enhanced awake SWI, mild/moderate evolution in adulthood and language disorder due to speech/oro-motor dyspraxia. SIGNIFICANCE: Our findings expand the phenotypic spectrum of CNKSR2-related ESES.

14.
Neuron ; 106(3): 404-420.e8, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32135084

RESUMO

De novo germline mutations in the RNA helicase DDX3X account for 1%-3% of unexplained intellectual disability (ID) cases in females and are associated with autism, brain malformations, and epilepsy. Yet, the developmental and molecular mechanisms by which DDX3X mutations impair brain function are unknown. Here, we use human and mouse genetics and cell biological and biochemical approaches to elucidate mechanisms by which pathogenic DDX3X variants disrupt brain development. We report the largest clinical cohort to date with DDX3X mutations (n = 107), demonstrating a striking correlation between recurrent dominant missense mutations, polymicrogyria, and the most severe clinical outcomes. We show that Ddx3x controls cortical development by regulating neuron generation. Severe DDX3X missense mutations profoundly disrupt RNA helicase activity, induce ectopic RNA-protein granules in neural progenitors and neurons, and impair translation. Together, these results uncover key mechanisms underlying DDX3X syndrome and highlight aberrant RNA metabolism in the pathogenesis of neurodevelopmental disease.


Assuntos
Córtex Cerebral/metabolismo , RNA Helicases DEAD-box/genética , Mutação de Sentido Incorreto , Transtornos do Neurodesenvolvimento/genética , Neurogênese , Animais , Linhagem Celular Tumoral , Células Cultivadas , Córtex Cerebral/anormalidades , Córtex Cerebral/embriologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Transtornos do Neurodesenvolvimento/patologia , RNA/metabolismo
15.
Thyroid ; 30(8): 1217-1221, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32204686

RESUMO

Resistance to thyroid hormone alpha (RTHα) is a rare and under-recognized genetic disease caused by mutations of THRA, the gene encoding thyroid hormone receptor α1 (TRα1). We report here two novel THRA missense mutations (M259T, T273A) in patients with RTHα. We combined biochemical and cellular assays with in silico modeling to assess the capacity of mutant TRα1 to bind triiodothyronine (T3), to heterodimerize with RXR, to interact with transcriptional coregulators, and to transduce a T3 transcriptional response. M259T, and to a lower extent T273A, reduces the affinity of TRα1 for T3. Their negative influence is only reverted by large excess of T3. The severity of the two novel RTHα cases originates from a reduction in the binding affinity of TRα1 mutants to T3 and thus correlates with the incapacity of corepressors to dissociate from TRα1 mutants in the presence of T3.

16.
Eur J Hum Genet ; 28(6): 770-782, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32005960

RESUMO

TBR1, a T-box transcription factor expressed in the cerebral cortex, regulates the expression of several candidate genes for autism spectrum disorders (ASD). Although TBR1 has been reported as a high-confidence risk gene for ASD and intellectual disability (ID) in functional and clinical reports since 2011, TBR1 has only recently been recorded as a human disease gene in the OMIM database. Currently, the neurodevelopmental disorders and structural brain anomalies associated with TBR1 variants are not well characterized. Through international data sharing, we collected data from 25 unreported individuals and compared them with data from the literature. We evaluated structural brain anomalies in seven individuals by analysis of MRI images, and compared these with anomalies observed in TBR1 mutant mice. The phenotype included ID in all individuals, associated to autistic traits in 76% of them. No recognizable facial phenotype could be identified. MRI analysis revealed a reduction of the anterior commissure and suggested new features including dysplastic hippocampus and subtle neocortical dysgenesis. This report supports the role of TBR1 in ID associated with autistic traits and suggests new structural brain malformations in humans. We hope this work will help geneticists to interpret TBR1 variants and diagnose ASD probands.

17.
Am J Hum Genet ; 106(3): 356-370, 2020 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-32109418

RESUMO

Genetic syndromes frequently present with overlapping clinical features and inconclusive or ambiguous genetic findings which can confound accurate diagnosis and clinical management. An expanding number of genetic syndromes have been shown to have unique genomic DNA methylation patterns (called "episignatures"). Peripheral blood episignatures can be used for diagnostic testing as well as for the interpretation of ambiguous genetic test results. We present here an approach to episignature mapping in 42 genetic syndromes, which has allowed the identification of 34 robust disease-specific episignatures. We examine emerging patterns of overlap, as well as similarities and hierarchical relationships across these episignatures, to highlight their key features as they are related to genetic heterogeneity, dosage effect, unaffected carrier status, and incomplete penetrance. We demonstrate the necessity of multiclass modeling for accurate genetic variant classification and show how disease classification using a single episignature at a time can sometimes lead to classification errors in closely related episignatures. We demonstrate the utility of this tool in resolving ambiguous clinical cases and identification of previously undiagnosed cases through mass screening of a large cohort of subjects with developmental delays and congenital anomalies. This study more than doubles the number of published syndromes with DNA methylation episignatures and, most significantly, opens new avenues for accurate diagnosis and clinical assessment in individuals affected by these disorders.


Assuntos
Metilação de DNA , Transtornos do Neurodesenvolvimento/genética , Fenótipo , Estudos de Coortes , Heterogeneidade Genética , Humanos , Síndrome
18.
Hum Mutat ; 41(4): 837-849, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31898846

RESUMO

IFIH1 gain-of-function has been reported as a cause of a type I interferonopathy encompassing a spectrum of autoinflammatory phenotypes including Aicardi-Goutières syndrome and Singleton Merten syndrome. Ascertaining patients through a European and North American collaboration, we set out to describe the molecular, clinical and interferon status of a cohort of individuals with pathogenic heterozygous mutations in IFIH1. We identified 74 individuals from 51 families segregating a total of 27 likely pathogenic mutations in IFIH1. Ten adult individuals, 13.5% of all mutation carriers, were clinically asymptomatic (with seven of these aged over 50 years). All mutations were associated with enhanced type I interferon signaling, including six variants (22%) which were predicted as benign according to multiple in silico pathogenicity programs. The identified mutations cluster close to the ATP binding region of the protein. These data confirm variable expression and nonpenetrance as important characteristics of the IFIH1 genotype, a consistent association with enhanced type I interferon signaling, and a common mutational mechanism involving increased RNA binding affinity or decreased efficiency of ATP hydrolysis and filament disassembly rate.

19.
Am J Hum Genet ; 106(2): 234-245, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-31928709

RESUMO

Germline pathogenic variants in chromatin-modifying enzymes are a common cause of pediatric developmental disorders. These enzymes catalyze reactions that regulate epigenetic inheritance via histone post-translational modifications and DNA methylation. Cytosine methylation (5-methylcytosine [5mC]) of DNA is the quintessential epigenetic mark, yet no human Mendelian disorder of DNA demethylation has yet been delineated. Here, we describe in detail a Mendelian disorder caused by the disruption of DNA demethylation. TET3 is a methylcytosine dioxygenase that initiates DNA demethylation during early zygote formation, embryogenesis, and neuronal differentiation and is intolerant to haploinsufficiency in mice and humans. We identify and characterize 11 cases of human TET3 deficiency in eight families with the common phenotypic features of intellectual disability and/or global developmental delay; hypotonia; autistic traits; movement disorders; growth abnormalities; and facial dysmorphism. Mono-allelic frameshift and nonsense variants in TET3 occur throughout the coding region. Mono-allelic and bi-allelic missense variants localize to conserved residues; all but one such variant occur within the catalytic domain, and most display hypomorphic function in an assay of catalytic activity. TET3 deficiency and other Mendelian disorders of the epigenetic machinery show substantial phenotypic overlap, including features of intellectual disability and abnormal growth, underscoring shared disease mechanisms.


Assuntos
Desmetilação do DNA , Deficiências do Desenvolvimento/genética , Deficiências do Desenvolvimento/patologia , Dioxigenases/deficiência , Adulto , Sequência de Aminoácidos , Transtorno Autístico/genética , Transtorno Autístico/patologia , Criança , Pré-Escolar , Dioxigenases/química , Dioxigenases/genética , Desenvolvimento Embrionário , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Transtornos do Crescimento/genética , Transtornos do Crescimento/patologia , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Transtornos dos Movimentos/genética , Transtornos dos Movimentos/patologia , Linhagem , Conformação Proteica , Homologia de Sequência , Adulto Jovem
20.
Artigo em Inglês | MEDLINE | ID: mdl-31926053

RESUMO

Developmental and Epileptic encephalopathies (DEE) describe heterogeneous epilepsy syndromes, characterized by early-onset, refractory seizures and developmental delay (DD). Several DEE associated genes have been reported. With increased access to whole exome sequencing (WES), new candidate genes are being identified although there are fewer large cohort papers describing the clinical phenotype in such patients. We describe 6 unreported individuals and provide updated information on an additional previously reported individual with heterozygous de novo missense variants in YWHAG. We describe a syndromal phenotype, report 5 novel, and a recurrent p.Arg132Cys YWHAG variant and compare developmental trajectory and treatment strategies in this cohort. We provide further evidence of causality in YWHAG variants. WES was performed in five patients via Deciphering Developmental Disorders Study and the remaining two were identified via Genematcher and AnnEX databases. De novo variants identified from exome data were validated using Sanger sequencing. Seven out of seven patients in the cohort have de novo, heterozygous missense variants in YWHAG including 2/7 patients with a recurrent c.394C > T, p.Arg132Cys variant; 1/7 has a second, pathogenic variant in STAG1. Characteristic features included: early-onset seizures, predominantly generalized tonic-clonic and absence type (7/7) with good response to standard anti-epileptic medications; moderate DD; Intellectual Disability (ID) (5/7) and Autism Spectrum Disorder (3/7). De novo YWHAG missense variants cause EE, characterized by early-onset epilepsy, ID and DD, supporting the hypothesis that YWHAG loss-of-function causes a neurological phenotype. Although the exact mechanism of disease resulting from alterations in YWHAG is not fully known, it is possible that haploinsufficiency of YWHAG in developing cerebral cortex may lead to abnormal neuronal migration resulting in DEE.

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