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1.
Transl Psychiatry ; 9(1): 267, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31636273

RESUMO

Despite the substantial progress made in identifying genetic defects in autism spectrum disorder (ASD), the etiology for majority of ASD individuals remains elusive. Maternal exposure to valproic acid (VPA), a commonly prescribed antiepileptic drug during pregnancy in human, has long been considered a risk factor to contribute to ASD susceptibility in offspring from epidemiological studies in humans. The similar exposures in murine models have provided tentative evidence to support the finding from human epidemiology. However, the apparent difference between rodent and human poses a significant challenge to extrapolate the findings from rodent models to humans. Here we report for the first time the neurodevelopmental and behavioral outcomes of maternal VPA exposure in non-human primates. Monkey offspring from the early maternal VPA exposure have significantly reduced NeuN-positive mature neurons in prefrontal cortex (PFC) and cerebellum and the Ki67-positive proliferating neuronal precursors in the cerebellar external granular layer, but increased GFAP-positive astrocytes in PFC. Transcriptome analyses revealed that maternal VPA exposure disrupted the expression of genes associated with neurodevelopment in embryonic brain in offspring. VPA-exposed juvenile offspring have variable presentations of impaired social interaction, pronounced stereotypies, and more attention on nonsocial stimuli by eye tracking analysis. Our findings in non-human primates provide the best evidence so far to support causal link between maternal VPA exposure and neurodevelopmental defects and ASD susceptibility in humans.

2.
Proc Natl Acad Sci U S A ; 116(39): 19717-19726, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31451636

RESUMO

Giant ankyrin-G (gAnkG) coordinates assembly of axon initial segments (AISs), which are sites of action potential generation located in proximal axons of most vertebrate neurons. Here, we identify a mechanism required for normal neural development in humans that ensures ordered recruitment of gAnkG and ß4-spectrin to the AIS. We identified 3 human neurodevelopmental missense mutations located in the neurospecific domain of gAnkG that prevent recruitment of ß4-spectrin, resulting in a lower density and more elongated pattern for gAnkG and its partners than in the mature AIS. We found that these mutations inhibit transition of gAnkG from a closed configuration with close apposition of N- and C-terminal domains to an extended state that is required for binding and recruitment of ß4-spectrin, and normally occurs early in development of the AIS. We further found that the neurospecific domain is highly phosphorylated in mouse brain, and that phosphorylation at 2 sites (S1982 and S2619) is required for the conformational change and for recruitment of ß4-spectrin. Together, these findings resolve a discrete intermediate stage in formation of the AIS that is regulated through phosphorylation of the neurospecific domain of gAnkG.

3.
Clin Genet ; 2019 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-31448412

RESUMO

While genomic sequencing (ES/GS) has the potential to diagnose children with difficult to diagnose phenotypes, the goal should be not only a diagnosis, but also to empower parents to seek next steps for their children and to emotionally manage the outcome, whether or not a diagnosis is secured. To help achieve this goal, objective measures are needed to assess the process of parental empowerment related to genome sequencing. We present the validity and reliability of the Genome Empowerment Scale (GEmS), developed using a healthcare empowerment theoretical model. To evaluate its psychometric properties, 158 parents of 117 children with an undiagnosed condition undergoing genomic sequencing completed the GEmS, measures for criterion validity and for depression and anxiety. Factor analysis resulted in a four factor solution: (a) meaning of a diagnosis; (b) emotional management of the process; (c) seeking information and support and (d) implications and planning. Reliability and validity analyses show that the GEmS has good psychometric properties. The inter-relationships among the factors revealed a profile that may identify parents at risk for a poorer outcome who may benefit from targeted genetic counseling. The GEmS, an objective measure of parental genomic empowerment, can be utilized for future research and translational applications.

4.
Am J Hum Genet ; 105(3): 640-657, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31402090

RESUMO

The identification of genetic variants implicated in human developmental disorders has been revolutionized by second-generation sequencing combined with international pooling of cases. Here, we describe seven individuals who have diverse yet overlapping developmental anomalies, and who all have de novo missense FBXW11 variants identified by whole exome or whole genome sequencing and not reported in the gnomAD database. Their phenotypes include striking neurodevelopmental, digital, jaw, and eye anomalies, and in one individual, features resembling Noonan syndrome, a condition caused by dysregulated RAS signaling. FBXW11 encodes an F-box protein, part of the Skp1-cullin-F-box (SCF) ubiquitin ligase complex, involved in ubiquitination and proteasomal degradation and thus fundamental to many protein regulatory processes. FBXW11 targets include ß-catenin and GLI transcription factors, key mediators of Wnt and Hh signaling, respectively, critical to digital, neurological, and eye development. Structural analyses indicate affected residues cluster at the surface of the loops of the substrate-binding domain of FBXW11, and the variants are predicted to destabilize the protein and/or its interactions. In situ hybridization studies on human and zebrafish embryonic tissues demonstrate FBXW11 is expressed in the developing eye, brain, mandibular processes, and limb buds or pectoral fins. Knockdown of the zebrafish FBXW11 orthologs fbxw11a and fbxw11b resulted in embryos with smaller, misshapen, and underdeveloped eyes and abnormal jaw and pectoral fin development. Our findings support the role of FBXW11 in multiple developmental processes, including those involving the brain, eye, digits, and jaw.

5.
Trends Pharmacol Sci ; 40(9): 605-608, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31353046

RESUMO

Prader-Willi syndrome (PWS) is a neurobehavioral and epigenetic disorder caused by the deficiency of paternally expressed genes in the chromosome 15q11-q13. This unique molecular defect renders PWS an exciting opportunity to explore epigenetic therapy. Here, we briefly highlight recent findings from small molecule screening and CRISPR/Cas9-mediated epigenome editing that offer promising therapeutic options along with the challenges that remain in developing a successful epigenetic therapy for PWS in humans.

6.
Proc Natl Acad Sci U S A ; 116(30): 15262-15271, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31285321

RESUMO

Giant ankyrin-B (ankB) is a neurospecific alternatively spliced variant of ANK2, a high-confidence autism spectrum disorder (ASD) gene. We report that a mouse model for human ASD mutation of giant ankB exhibits increased axonal branching in cultured neurons with ectopic CNS axon connectivity, as well as with a transient increase in excitatory synapses during postnatal development. We elucidate a mechanism normally limiting axon branching, whereby giant ankB localizes to periodic axonal plasma membrane domains through L1 cell-adhesion molecule protein, where it couples microtubules to the plasma membrane and prevents microtubule entry into nascent axon branches. Giant ankB mutation or deficiency results in a dominantly inherited impairment in selected communicative and social behaviors combined with superior executive function. Thus, gain of axon branching due to giant ankB-deficiency/mutation is a candidate cellular mechanism to explain aberrant structural connectivity and penetrant behavioral consequences in mice as well as humans bearing ASD-related ANK2 mutations.

9.
Transl Res ; 208: 105-118, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30904443

RESUMO

Prader-Willi syndrome (PWS) is a complex and multisystem neurobehavioral disorder. The molecular mechanism of PWS is deficiency of paternally expressed gene gene or genes from the chromosome 15q11-q13. Due to imprinted gene regulation, the same genes in the maternal chromosome 15q11-q13 are structurally intact but transcriptionally repressed by an epigenetic mechanism. The unique molecular defect underlying PWS renders an exciting opportunity to explore epigenetic-based therapy to reactivate the expression of repressed PWS genes from the maternal chromosome. Inactivation of H3K9m3 methyltransferase SETDB1 and zinc finger protein ZNF274 results in reactivation of SNRPN and SNORD116 cluster from the maternal chromosomes in PWS patient iPSCs and iPSC-derived neurons, respectively. High content screening of small molecule libraries using cells derived from transgenic mice carrying the SNRPN-EGFP fusion protein has discovered that inhibitors of EHMT2/G9a, a histone 3 lysine 9 methyltransferase, are capable of reactivating expression of paternally expressed SNRPN and SNORD116 from the maternal chromosome, both in cultured PWS patient-derived fibroblasts and in a PWS mouse model. Treatment with an EMHT2/G9a inhibitor also rescues perinatal lethality and failure to thrive phenotypes in a PWS mouse model. These findings present the first evidence to support a proof-of-principle for epigenetic-based therapy for the PWS in humans.


Assuntos
Epigênese Genética , Síndrome de Prader-Willi/genética , Animais , Cromossomos Humanos Par 15 , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Camundongos , Camundongos Transgênicos , Metiltransferases de Proteína/metabolismo , RNA Nucleolar Pequeno/genética
11.
Annu Rev Med ; 70: 151-166, 2019 01 27.
Artigo em Inglês | MEDLINE | ID: mdl-30691368

RESUMO

The prevalence of autism spectrum disorder (ASD) has been increasing steadily over the last 20 years; however, the molecular basis for the majority of ASD cases remains unknown. Recent advances in next-generation sequencing and detection of DNA modifications have made methylation-dependent regulation of transcription an attractive hypothesis for being a causative factor in ASD etiology. Evidence for abnormal DNA methylation in ASD can be seen on multiple levels, from genetic mutations in epigenetic machinery to loci-specific and genome-wide changes in DNA methylation. Epimutations in DNA methylation can be acquired throughout life, as global DNA methylation reprogramming is dynamic during embryonic development and the early postnatal period that corresponds to the peak time of synaptogenesis. However, technical advances and causative evidence still need to be established before abnormal DNA methylation and ASD can be confidently associated.

12.
Am J Hum Genet ; 104(1): 164-178, 2019 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-30580808

RESUMO

SMARCC2 (BAF170) is one of the invariable core subunits of the ATP-dependent chromatin remodeling BAF (BRG1-associated factor) complex and plays a crucial role in embryogenesis and corticogenesis. Pathogenic variants in genes encoding other components of the BAF complex have been associated with intellectual disability syndromes. Despite its significant biological role, variants in SMARCC2 have not been directly associated with human disease previously. Using whole-exome sequencing and a web-based gene-matching program, we identified 15 individuals with variable degrees of neurodevelopmental delay and growth retardation harboring one of 13 heterozygous variants in SMARCC2, most of them novel and proven de novo. The clinical presentation overlaps with intellectual disability syndromes associated with other BAF subunits, such as Coffin-Siris and Nicolaides-Baraitser syndromes and includes prominent speech impairment, hypotonia, feeding difficulties, behavioral abnormalities, and dysmorphic features such as hypertrichosis, thick eyebrows, thin upper lip vermilion, and upturned nose. Nine out of the fifteen individuals harbor variants in the highly conserved SMARCC2 DNA-interacting domains (SANT and SWIRM) and present with a more severe phenotype. Two of these individuals present cardiac abnormalities. Transcriptomic analysis of fibroblasts from affected individuals highlights a group of differentially expressed genes with possible roles in regulation of neuronal development and function, namely H19, SCRG1, RELN, and CACNB4. Our findings suggest a novel SMARCC2-related syndrome that overlaps with neurodevelopmental disorders associated with variants in BAF-complex subunits.


Assuntos
Deficiências do Desenvolvimento/complicações , Deficiências do Desenvolvimento/genética , Deficiência Intelectual/complicações , Deficiência Intelectual/genética , Mutação , Fatores de Transcrição/genética , Anormalidades Múltiplas/genética , Adolescente , Criança , Pré-Escolar , Face/anormalidades , Feminino , Deformidades Congênitas da Mão/genética , Humanos , Masculino , Micrognatismo/genética , Pescoço/anormalidades , Síndrome
13.
JCI Insight ; 3(23)2018 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-30518695

RESUMO

OXTR modulates a variety of behaviors in mammals, including social memory and recognition. Genetic and epigenetic dysregulation of OXTR has been suggested to be implicated in neuropsychiatric disorders, including autism spectrum disorder (ASD). While the involvement of DNA methylation is suggested, the mechanism underlying epigenetic regulation of OXTR is largely unknown. This has hampered the experimental design and interpretation of the results of epigenetic studies of OXTR in neuropsychiatric disorders. From the generation and characterization of a new line of Tet1 mutant mice - by deleting the largest coding exon 4 (Tet1Δe4) - we discovered for the first time to our knowledge that Oxtr has an array of mRNA isoforms and a complex transcriptional regulation. Select isoforms of Oxtr are significantly reduced in the brain of Tet1Δe4-/- mice. Accordingly, CpG islands of Oxtr are hypermethylated during early development and persist into adulthood. Consistent with the reduced express of OXTR, Tet1Δe4-/- mice display impaired maternal care, social behavior, and synaptic responses to oxytocin stimulation. Our findings elucidate a mechanism mediated by TET1 protein in regulating Oxtr expression by preventing DNA hypermethylation of Oxtr. The discovery of epigenetic dysregulation of Oxtr in TET1-deficient mouse brain supports the necessity of a reassessment of existing findings and a value of future studies of OXTR in neuropsychiatric disorders.

14.
Mol Autism ; 9: 65, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30574290

RESUMO

Background: Mutations in CHD8, chromodomain helicase DNA-binding protein 8, are among the most replicated and common findings in genetic studies of autism spectrum disorder (ASD). The CHD8 protein is believed to act as a transcriptional regulator by remodeling chromatin structure and recruiting histone H1 to target genes. The mechanism by which deficiency of CHD8 causes ASD has not been fully elucidated. Methods: We examined the expression of CHD8 in human and mouse brains using both immunohistochemistry and RNA in situ hybridization. We performed in utero electroporation, neuronal culture, and biochemical analysis using RNAi to examine the functional consequences of CHD8 deficiency. Results: We discovered that CHD8 is expressed highly in neurons and at low levels in glia cells in both humans and mice. Specifically, CHD8 is localized predominately in the nucleus of both MAP2 and parvalbumin-positive neurons. In the developing mouse brain, expression of Chd8 peaks from E16 to E18 and then decreases significantly at P14 to adulthood. Knockdown of Chd8 results in reduced axon and dendritic growth, disruption of axon projections to the contralateral cortex, and delayed neuronal migration at E18.5 which recovers by P3 and P7. Conclusion: Our findings indicate an important role for CHD8 in dendritic and axon development and neuronal migration and thus offer novel insights to further dissect the underlying molecular and circuit mechanisms of ASD caused by CHD8 deficiency.


Assuntos
Transtorno Autístico/genética , Proteínas de Ligação a DNA/genética , Neurogênese , Neurônios/metabolismo , Animais , Transtorno Autístico/patologia , Células Cultivadas , Córtex Cerebral/citologia , Córtex Cerebral/crescimento & desenvolvimento , Proteínas de Ligação a DNA/metabolismo , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Neurônios/fisiologia
15.
J Genet Genomics ; 45(10): 527-538, 2018 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-30392784

RESUMO

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with considerable clinical and genetic heterogeneity. In this study, we identified all classes of genomic variants from whole-genome sequencing (WGS) dataset of 32 Chinese trios with ASD, including de novo mutations, inherited variants, copy number variants (CNVs) and genomic structural variants. A higher mutation rate (Poisson test, P < 2.2 × 10-16) in exonic (1.37 × 10-8) and 3'-UTR regions (1.42 × 10-8) was revealed in comparison with that of whole genome (1.05 × 10-8). Using an integrated model, we identified 87 potentially risk genes (P < 0.01) from 4832 genes harboring various rare deleterious variants, including CHD8 and NRXN2, implying that the disorders may be in favor to multiple-hit. In particular, frequent rare inherited mutations of several microcephaly-associated genes (ASPM, WDR62, and ZNF335) were found in ASD. In chromosomal structure analyses, we found four de novo CNVs and one de novo chromosomal rearrangement event, including a de novo duplication of UBE3A-containing region at 15q11.2-q13.1, which causes Angelman syndrome and microcephaly, and a disrupted TNR due to de novo chromosomal translocation t(1; 5)(q25.1; q33.2). Taken together, our results suggest that abnormalities of centrosomal function and chromatin remodeling of the microcephaly-associated genes may be implicated in pathogenesis of ASD. Adoption of WGS as a new yet efficient technique to illustrate the full genetic spectrum in complex disorders, such as ASD, could provide novel insights into pathogenesis, diagnosis and treatment.

16.
Biol Psychiatry ; 2018 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-30466882

RESUMO

BACKGROUND: Autism spectrum disorder involves neurodevelopmental dysregulations that lead to visible symptoms at early stages of life. Many autism spectrum disorder-related mechanisms suggested by animal studies are supported by demonstrated improvement in autistic-like phenotypes in adult animals following experimental reversal of dysregulated mechanisms. However, whether such mechanisms also act at earlier stages to cause autistic-like phenotypes is unclear. METHODS: We used Shank2-/- mice carrying a mutation identified in human autism spectrum disorder (exons 6 and 7 deletion) and combined electrophysiological and behavioral analyses to see whether early pathophysiology at pup stages is different from late pathophysiology at juvenile and adult stages and whether correcting early pathophysiology can normalize late pathophysiology and abnormal behaviors in juvenile and adult mice. RESULTS: Early correction of a dysregulated mechanism in young mice prevents manifestation of autistic-like social behaviors in adult mice. Shank2-/- mice, known to display N-methyl-D-aspartate receptor (NMDAR) hypofunction and autistic-like behaviors at postweaning stages after postnatal day 21 (P21), show the opposite synaptic phenotype-NMDAR hyperfunction-at an earlier preweaning stage (∼P14). Moreover, this NMDAR hyperfunction at P14 rapidly shifts to NMDAR hypofunction after weaning (∼P24). Chronic suppression of the early NMDAR hyperfunction by the NMDAR antagonist memantine (P7-P21) prevents NMDAR hypofunction and autistic-like social behaviors from manifesting at later stages (∼P28 and P56). CONCLUSIONS: Early NMDAR hyperfunction leads to late NMDAR hypofunction and autistic-like social behaviors in Shank2-/- mice, and early correction of NMDAR dysfunction has the long-lasting effect of preventing autistic-like social behaviors from developing at later stages.

17.
Hum Mol Genet ; 2018 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-30329048

RESUMO

Monogenic mutations in the SHANK3 gene, which encodes a postsynaptic scaffold protein, play a causative role in autism spectrum disorder (ASD). Although a number of mouse models with Shank3 mutations have been valuable for investigating the pathogenesis of ASD, species-dependent differences in behaviors and brain structures post considerable challenges to use small animals to model ASD and to translate experimental therapeutics to the clinic. We have used CRISPR/Cas9 to generate a cynomolgus monkey model by disrupting SHANK3 at exon 6 and 12. Analysis of the live mutant monkey revealed the core behavioral abnormalities of ASD, including impaired social interaction and repetitive behaviors, and reduced brain network activities detected by positron-emission tomography (PET). Importantly, these abnormal behaviors and brain activities were alleviated by the antidepressant fluoxetine treatment. Our findings provide the first demonstration that the genetically modified non-human primate can be used for translational research of therapeutics for ASD.

18.
BMC Med Genomics ; 11(1): 92, 2018 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-30352594

RESUMO

BACKGROUND: Verheij syndrome is a rare microdeletion syndrome of chromosome 8q24.3 that harbors PUF60, SCRIB, and NRBP2 genes. Subsequently, loss of function mutations in PUF60 have been found in children with clinical features significantly overlapping with Verheij. CASE PRESENTATION: Here we present the first Chinese Han patient with a de novo nonsense variant (c.1357C > T, p.Gln453*) in PUF60 by clinical whole exome sequencing. The 5-year-old boy presents with dysmorphic facial features, intellectual disability, and growth retardation but without apparent cardiac, renal, ocular, and spinal anomalies. CONCLUSIONS: Our finding contributes to the understanding of the genotype and phenotype in PUF60 related disorder.

19.
Brain Behav ; 8(11): e01107, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30317697

RESUMO

INTRODUCTION: Several studies have supported the use of enriched environments to prevent the manifestation of ASD-like phenotypes in laboratory rodents. While the translational value of such experiments is unknown, the findings have been relatively consistent across many different models. METHODS: In the current study, we tested the effects of early environmental enrichment on a mouse model of ASD with high construct validity, the Shank3 ∆e4-22 mice our laboratory previously generated and characterized. RESULTS: Contrary to previous reports, we found no benefits of enriched rearing, including no change in repetitive self-grooming or hole-board exploration. Instead, we found that early environmental enrichment increased anxiety-like behavior in all mice regardless of genotype and decreased motor performance specifically in wild-type mice. CONCLUSIONS: Although using a different enrichment protocol may have rescued the phenotypes in our mouse model, these results suggest that a "one-size fits all" approach may not be the best when it comes to behavioral intervention for ASD and underscores the need for effective pharmaceutical development in certain genetic syndromes with severe symptom presentation.

20.
BMC Health Serv Res ; 18(1): 652, 2018 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-30134969

RESUMO

BACKGROUND: The majority of undiagnosed diseases manifest with objective findings that warrant further investigation. The Undiagnosed Diseases Network (UDN) receives applications from patients whose symptoms and signs have been intractable to diagnosis; however, many UDN applicants are affected primarily by subjective symptoms such as pain and fatigue. We sought to characterize presenting symptoms, referral sources, and demographic factors of applicants to the UDN to identify factors that may determine application outcome and potentially differentiate between those with undiagnosed diseases (with more objective findings) and those who are less likely to have an undiagnosed disease (more subjective symptoms). METHODS: We used a systematic retrospective review of 151 consecutive Not Accepted and 50 randomly selected Accepted UDN applications. The primary outcome was whether an applicant was Accepted, or Not Accepted, and, if accepted, whether or not a diagnosis was made. Objective and subjective symptoms and information on prior specialty consultations were collected from provider referral letters. Demographic data and decision data on network acceptance were gathered from the UDN online portal. RESULTS: Fewer objective findings and more subjective symptoms were found in the Not Accepted applications. Not Accepted referrals also were from older individuals, reported a shorter period of illness, and were referred to the UDN by their primary care physicians. All of these differences reached statistical significance in comparison with Accepted applications. The frequency of subspecialty consults for diagnostic purposes prior to UDN application was similar in both groups. CONCLUSIONS: The preponderance of subjective and lack of objective findings in the Not Accepted applications distinguish these from applicants that are accepted for evaluation and diagnostic efforts through the UDN. Not Accepted applicants are referred primarily by their primary care providers after multiple specialist consultations fail to yield answers. Distinguishing between patients with undiagnosed diseases with objective findings and those with primarily subjective findings can delineate patients who would benefit from further diagnostic processes from those who may have functional disorders and need alternative pathways for management of their symptoms. TRIAL REGISTRATION: clinicaltrials.gov NCT02450851 , posted May 21st 2015.

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