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1.
Am J Hum Genet ; 104(3): 530-541, 2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30827496

RESUMO

Acetylation of the lysine residues in histones and other DNA-binding proteins plays a major role in regulation of eukaryotic gene expression. This process is controlled by histone acetyltransferases (HATs/KATs) found in multiprotein complexes that are recruited to chromatin by the scaffolding subunit transformation/transcription domain-associated protein (TRRAP). TRRAP is evolutionarily conserved and is among the top five genes intolerant to missense variation. Through an international collaboration, 17 distinct de novo or apparently de novo variants were identified in TRRAP in 24 individuals. A strong genotype-phenotype correlation was observed with two distinct clinical spectra. The first is a complex, multi-systemic syndrome associated with various malformations of the brain, heart, kidneys, and genitourinary system and characterized by a wide range of intellectual functioning; a number of affected individuals have intellectual disability (ID) and markedly impaired basic life functions. Individuals with this phenotype had missense variants clustering around the c.3127G>A p.(Ala1043Thr) variant identified in five individuals. The second spectrum manifested with autism spectrum disorder (ASD) and/or ID and epilepsy. Facial dysmorphism was seen in both groups and included upslanted palpebral fissures, epicanthus, telecanthus, a wide nasal bridge and ridge, a broad and smooth philtrum, and a thin upper lip. RNA sequencing analysis of skin fibroblasts derived from affected individuals skin fibroblasts showed significant changes in the expression of several genes implicated in neuronal function and ion transport. Thus, we describe here the clinical spectrum associated with TRRAP pathogenic missense variants, and we suggest a genotype-phenotype correlation useful for clinical evaluation of the pathogenicity of the variants.

2.
Eur J Hum Genet ; 27(7): 1081-1089, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30778173

RESUMO

Hexokinase 1 (HK1) phosphorylates glucose to glucose-6-phosphate, the first rate-limiting step in glycolysis. Homozygous and heterozygous variants in HK1 have been shown to cause autosomal recessive non-spherocytic hemolytic anemia, autosomal recessive Russe type hereditary motor and sensory neuropathy, and autosomal dominant retinitis pigmentosa (adRP). We report seven patients from six unrelated families with a neurodevelopmental disorder associated with developmental delay, intellectual disability, structural brain abnormality, and visual impairments in whom we identified four novel, de novo missense variants in the N-terminal half of HK1. Hexokinase activity in red blood cells of two patients was normal, suggesting that the disease mechanism is not due to loss of hexokinase enzymatic activity.

3.
Am J Med Genet A ; 176(9): 1845-1851, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30055086

RESUMO

Gross deletions involving the MEIS2 gene have been described in a small number of patients with overlapping phenotypes of atrial or ventricular septal defects, cleft palate, and variable developmental delays and intellectual disability. Non-specific dysmorphic features were noted in some patients, including broad forehead with high anterior hairline, arched eyebrows, thin or tented upper lip, and short philtrum. Recently, a patient with a de novo single amino acid deletion, c.998_1000delGAA (p.Arg333del), and a patient with a de novo nonsense variant, (c.611C>G, p.Ser204*), were reported with a similar, but apparently more severe phenotypes. Clinical whole exome sequencing (WES) performed at our clinical molecular diagnostic laboratory identified four additional patients with predicted damaging de novo MEIS2 missense variants. Our patients' features closely resembled those previously reported in patients with gross deletions, but also included some less commonly reported features, such as autism spectrum disorder, hearing loss, and short stature, as well as features that may be unique to nucleotide-level variants, such as hypotonia, failure to thrive, gastrointestinal, skeletal, limb, and skin abnormalities. All of the observed missense variants, Pro302Leu, Gln322Leu, Arg331Lys, and Val335Ala, are located in the functionally important MEIS2 homeodomain. Pro302Leu is found in the region between helix 1 and helix 2, while the other three are located in the DNA-binding helix 3. To our knowledge, these are the first described de novo missense variants in MEIS2, expanding the known mutation spectrum of the newly recognized human disorder caused by aberrations in this gene.

4.
Am J Hum Genet ; 102(5): 858-873, 2018 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-29727687

RESUMO

The exosome is a conserved multi-protein complex that is essential for correct RNA processing. Recessive variants in exosome components EXOSC3, EXOSC8, and RBM7 cause various constellations of pontocerebellar hypoplasia (PCH), spinal muscular atrophy (SMA), and central nervous system demyelination. Here, we report on four unrelated affected individuals with recessive variants in EXOSC9 and the effect of the variants on the function of the RNA exosome in vitro in affected individuals' fibroblasts and skeletal muscle and in vivo in zebrafish. The clinical presentation was severe, early-onset, progressive SMA-like motor neuronopathy, cerebellar atrophy, and in one affected individual, congenital fractures of the long bones. Three affected individuals of different ethnicity carried the homozygous c.41T>C (p.Leu14Pro) variant, whereas one affected individual was compound heterozygous for c.41T>C (p.Leu14Pro) and c.481C>T (p.Arg161∗). We detected reduced EXOSC9 in fibroblasts and skeletal muscle and observed a reduction of the whole multi-subunit exosome complex on blue-native polyacrylamide gel electrophoresis. RNA sequencing of fibroblasts and skeletal muscle detected significant >2-fold changes in genes involved in neuronal development and cerebellar and motor neuron degeneration, demonstrating the widespread effect of the variants. Morpholino oligonucleotide knockdown and CRISPR/Cas9-mediated mutagenesis of exosc9 in zebrafish recapitulated aspects of the human phenotype, as they have in other zebrafish models of exosomal disease. Specifically, portions of the cerebellum and hindbrain were absent, and motor neurons failed to develop and migrate properly. In summary, we show that variants in EXOSC9 result in a neurological syndrome combining cerebellar atrophy and spinal motoneuronopathy, thus expanding the list of human exosomopathies.

5.
Am J Med Genet C Semin Med Genet ; 178(2): 194-197, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29749690

RESUMO

New and rapidly evolving technologies have dramatically impacted the practice of clinical genetics as well as broader areas of medicine. To illustrate this trend from the perspective of a clinical molecular laboratory, we briefly summarize our general experience conducting exome testing for patients with holoprosencephaly (HPE). Though these cases are not representative of HPE more generally (i.e., cases undergoing exome sequencing represent a skewed sample), results include a 22% positive rate from exome testing. Of interest, 29% of reported results involved genes not considered to be classic HPE genes, indicating more evidence that HPE may fall within the severe spectrum of many other genetic conditions.

7.
Epilepsia ; 59(5): 1062-1071, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29655203

RESUMO

OBJECTIVE: We evaluated >8500 consecutive, unselected patients with epilepsy and neurodevelopmental disorders who underwent multigene panel testing to determine the average age at molecular diagnosis and diagnostic yield of 70 genes. METHODS: We reviewed molecular test results for 70 genes known to cause epilepsy and neurodevelopmental disorders using next generation sequencing (NGS) and exon-level array comparative genomic hybridization (aCGH). A positive result was defined as the presence of 1 or 2 pathogenic or likely pathogenic (P/LP) variants in a single gene, depending on the mode of inheritance of the associated disorder. RESULTS: Overall, 22 genes were found to have a high yield of positive findings by genetic testing, with SCN1A and KCNQ2 accounting for the greatest number of positive findings. In contrast, there were no positive findings in 16 genes. Most of the P/LP variants were sequence changes identified by NGS (90.9%), whereas ~9% were gross deletions or duplications detected by exon-level aCGH. The mean age of molecular diagnosis for the cohort was 5 years, 8 months (ranging from 1 week to 47 years). Recurrent P/LP variants were observed in 14 distinct genes, most commonly in MECP2, KCNQ2, SCN1A, SCN2A, STXBP1, and PRRT2. Parental testing was performed in >30% of positive cases. All variants identified in CDKL5, STXBP1, SCN8A, GABRA1, and FOXG1 were de novo, whereas 85.7% of variants in PRRT2 were inherited. SIGNIFICANCE: Using a combined approach of NGS and exon-level aCGH, testing identified a genetic etiology in 15.4% of patients in this cohort and revealed the age at molecular diagnosis for patients. Our study highlights both high- and low-yield genes associated with epilepsy and neurodevelopmental disorders, indicating which genes may be considered for molecular diagnostic testing.

8.
Genet Med ; 20(4): 403-410, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28837158

RESUMO

PurposeMosaicism probably represents an underreported cause of genetic disorders due to detection challenges during routine molecular diagnostics. The purpose of this study was to evaluate the frequency of mosaicism detected by next-generation sequencing in genes associated with epilepsy-related neurodevelopmental disorders.MethodsWe conducted a retrospective analysis of 893 probands with epilepsy who had a multigene epilepsy panel or whole-exome sequencing performed in a clinical diagnostic laboratory and were positive for a pathogenic or likely pathogenic variant in one of nine genes (CDKL5, GABRA1, GABRG2, GRIN2B, KCNQ2, MECP2, PCDH19, SCN1A, or SCN2A). Parental results were available for 395 of these probands.ResultsMosaicism was most common in the CDKL5, PCDH19, SCN2A, and SCN1A genes. Mosaicism was observed in GABRA1, GABRG2, and GRIN2B, which previously have not been reported to have mosaicism, and also in KCNQ2 and MECP2. Parental mosaicism was observed for pathogenic variants in multiple genes including KCNQ2, MECP2, SCN1A, and SCN2A.ConclusionMosaic pathogenic variants were identified frequently in nine genes associated with various neurological conditions. Given the potential clinical ramifications, our findings suggest that next-generation sequencing diagnostic methods may be utilized when testing these genes in a diagnostic laboratory.


Assuntos
Epilepsia/genética , Frequência do Gene , Predisposição Genética para Doença , Variação Genética , Mosaicismo , Transtornos do Neurodesenvolvimento/genética , Alelos , Substituição de Aminoácidos , Epilepsia/diagnóstico , Estudos de Associação Genética , Testes Genéticos , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Transtornos do Neurodesenvolvimento/diagnóstico , Pais , Sequenciamento Completo do Exoma
9.
Artigo em Inglês | MEDLINE | ID: mdl-29162653

RESUMO

Using whole-exome sequencing, we identified seven unrelated individuals with global developmental delay, hypotonia, dysmorphic facial features, and an increased frequency of short stature, ataxia, and autism with de novo heterozygous frameshift, nonsense, splice, and missense variants in the Early B-cell Transcription Factor Family Member 3 (EBF3) gene. EBF3 is a member of the collier/olfactory-1/early B-cell factor (COE) family of proteins, which are required for central nervous system (CNS) development. COE proteins are highly evolutionarily conserved and regulate neuronal specification, migration, axon guidance, and dendritogenesis during development and are essential for maintaining neuronal identity in adult neurons. Haploinsufficiency of EBF3 may affect brain development and function, resulting in developmental delay, intellectual disability, and behavioral differences observed in individuals with a deleterious variant in EBF3.


Assuntos
Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Adolescente , Sequência de Aminoácidos/genética , Ataxia/genética , Transtorno Autístico/genética , Criança , Pré-Escolar , Sequência Conservada/genética , Deficiências do Desenvolvimento/genética , Exoma , Feminino , Humanos , Lactente , Deficiência Intelectual , Masculino , Hipotonia Muscular/genética , Mutação , Transtornos do Neurodesenvolvimento/genética , Síndrome de Prader-Willi/genética , Sequenciamento Completo do Exoma/métodos , Adulto Jovem
10.
Am J Hum Genet ; 101(5): 664-685, 2017 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-29100083

RESUMO

Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.


Assuntos
Encefalopatias/genética , Epilepsia/genética , Mutação/genética , Criança , Pré-Escolar , Feminino , Genoma Humano/genética , Estudo de Associação Genômica Ampla/métodos , Humanos , Deficiência Intelectual/genética , Masculino , Recidiva , Convulsões/genética
11.
Am J Hum Genet ; 101(2): 239-254, 2017 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-28777931

RESUMO

The synthesis of all 13 mitochondrial DNA (mtDNA)-encoded protein subunits of the human oxidative phosphorylation (OXPHOS) system is carried out by mitochondrial ribosomes (mitoribosomes). Defects in the stability of mitoribosomal proteins or mitoribosome assembly impair mitochondrial protein translation, causing combined OXPHOS enzyme deficiency and clinical disease. Here we report four autosomal-recessive pathogenic mutations in the gene encoding the small mitoribosomal subunit protein, MRPS34, in six subjects from four unrelated families with Leigh syndrome and combined OXPHOS defects. Whole-exome sequencing was used to independently identify all variants. Two splice-site mutations were identified, including homozygous c.321+1G>T in a subject of Italian ancestry and homozygous c.322-10G>A in affected sibling pairs from two unrelated families of Puerto Rican descent. In addition, compound heterozygous MRPS34 mutations were identified in a proband of French ancestry; a missense (c.37G>A [p.Glu13Lys]) and a nonsense (c.94C>T [p.Gln32∗]) variant. We demonstrated that these mutations reduce MRPS34 protein levels and the synthesis of OXPHOS subunits encoded by mtDNA. Examination of the mitoribosome profile and quantitative proteomics showed that the mitochondrial translation defect was caused by destabilization of the small mitoribosomal subunit and impaired monosome assembly. Lentiviral-mediated expression of wild-type MRPS34 rescued the defect in mitochondrial translation observed in skin fibroblasts from affected subjects, confirming the pathogenicity of MRPS34 mutations. Our data establish that MRPS34 is required for normal function of the mitoribosome in humans and furthermore demonstrate the power of quantitative proteomic analysis to identify signatures of defects in specific cellular pathways in fibroblasts from subjects with inherited disease.


Assuntos
DNA Mitocondrial/genética , Doença de Leigh/genética , Doenças Mitocondriais/genética , Proteínas Mitocondriais/genética , Proteínas Ribossômicas/genética , Subunidades Ribossômicas Menores de Eucariotos/genética , Adolescente , Sequência de Bases , Criança , Pré-Escolar , Exoma/genética , Feminino , Humanos , Lactente , Doença de Leigh/enzimologia , Masculino , Mitocôndrias/genética , Fosforilação Oxidativa , Proteômica , Processamento de RNA/genética , Análise de Sequência de DNA
12.
Genet Med ; 19(10): 1171-1178, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28425981

RESUMO

PurposeThe aim of this study was to determine the diagnostic yield of whole-exome sequencing (WES) in fetuses with ultrasound anomalies that resulted in fetal demise or pregnancy termination. The results were also utilized to aid in the identification of candidate genes for fetal development and to expand the clinical phenotype of known genetic conditions.MethodsWES was performed on specimens from 84 deceased fetuses. Data were analyzed and final results were classified into one of four categories: positive, possible, negative, and candidate gene only. WES analysis was predominantly performed in fetus-parent trios or quads (61%, n=52).ResultsOverall, 20% (n = 17) of cases were positive, 45% (n=38) were possible, 9% (n=7) had only candidate gene variants and 26% (n = 22) tested negative. The diagnostic yield for definitive findings for trio analysis was 24% (n = 11) compared to 14% (n = 4) for singletons. The most frequently reported ultrasound anomalies were central nervous system (37%, n = 31), hydrops/edema (36%, n = 30), and cardiovascular anomalies (31%, n = 26).ConclusionOur experience supports the use of WES to identify the molecular etiology of fetal ultrasound anomalies, to identify candidate genes involved in fetal development, and to expand our knowledge of the clinical phenotype of known genetic conditions.


Assuntos
Desenvolvimento Fetal/genética , Diagnóstico Pré-Natal/métodos , Aborto Induzido , Exoma/genética , Feminino , Morte Fetal/etiologia , Feto/diagnóstico por imagem , Humanos , Masculino , Mutação , Fenótipo , Gravidez , Análise de Sequência de DNA/métodos , Ultrassonografia , Ultrassonografia Pré-Natal , Sequenciamento Completo do Exoma/métodos
13.
J Med Genet ; 54(2): 84-86, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27389779

RESUMO

BACKGROUND: The causes of intellectual disability (ID) are diverse and de novo mutations are increasingly recognised to account for a significant proportion of ID. METHODS AND RESULTS: In this study, we performed whole exome sequencing on a large cohort of patients with ID or neurodevelopmental delay and identified four novel de novo predicted deleterious missense variants in HECW2 in six probands with ID/developmental delay and hypotonia. Other common features include seizures, strabismus, nystagmus, cortical visual impairment and dysmorphic facial features. HECW2 is an ubiquitin ligase that stabilises p73, a crucial mediator of neurodevelopment and neurogenesis. CONCLUSION: This study implicates pathogenic genetic variants in HECW2 as potential causes of neurodevelopmental disorders in humans.


Assuntos
Deficiência Intelectual/genética , Hipotonia Muscular/genética , Transtornos do Neurodesenvolvimento/genética , Proteína Tumoral p73/genética , Ubiquitina-Proteína Ligases/genética , Criança , Pré-Escolar , Exoma/genética , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Deficiência Intelectual/patologia , Masculino , Hipotonia Muscular/patologia , Mutação de Sentido Incorreto/genética , Transtornos do Neurodesenvolvimento/patologia
14.
Cold Spring Harb Mol Case Stud ; 2(6): a001172, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27900362

RESUMO

Using whole-exome sequencing, we have identified novel de novo heterozygous pleckstrin homology domain-interacting protein (PHIP) variants that are predicted to be deleterious, including a frameshift deletion, in two unrelated patients with common clinical features of developmental delay, intellectual disability, anxiety, hypotonia, poor balance, obesity, and dysmorphic features. A nonsense mutation in PHIP has previously been associated with similar clinical features. Patients with microdeletions of 6q14.1, including PHIP, have a similar phenotype of developmental delay, intellectual disability, hypotonia, and obesity, suggesting that the phenotype of our patients is a result of loss-of-function mutations. PHIP produces multiple protein products, such as PHIP1 (also known as DCAF14), PHIP, and NDRP. PHIP1 is one of the multiple substrate receptors of the proteolytic CUL4-DDB1 ubiquitin ligase complex. CUL4B deficiency has been associated with intellectual disability, central obesity, muscle wasting, and dysmorphic features. The overlapping phenotype associated with CUL4B deficiency suggests that PHIP mutations cause disease through disruption of the ubiquitin ligase pathway.


Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/genética , Pré-Escolar , Deficiências do Desenvolvimento/genética , Exoma , Feminino , Mutação da Fase de Leitura , Heterozigoto , Humanos , Deficiência Intelectual/genética , Hipotonia Muscular/genética , Mutação , Obesidade/genética , Fenótipo , Domínios de Homologia à Plecstrina , Sequenciamento Completo do Exoma/métodos
15.
Hum Genet ; 135(12): 1399-1409, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27681385

RESUMO

Intellectual disabilities are genetically heterogeneous and can be associated with congenital anomalies. Using whole-exome sequencing (WES), we identified five different de novo missense variants in the protein phosphatase-1 catalytic subunit beta (PPP1CB) gene in eight unrelated individuals who share an overlapping phenotype of dysmorphic features, macrocephaly, developmental delay or intellectual disability (ID), congenital heart disease, short stature, and skeletal and connective tissue abnormalities. Protein phosphatase-1 (PP1) is a serine/threonine-specific protein phosphatase involved in the dephosphorylation of a variety of proteins. The PPP1CB gene encodes a PP1 subunit that regulates the level of protein phosphorylation. All five altered amino acids we observed are highly conserved among the PP1 subunit family, and all are predicted to disrupt PP1 subunit binding and impair dephosphorylation. Our data suggest that our heterozygous de novo PPP1CB pathogenic variants are associated with syndromic intellectual disability.


Assuntos
Estudos de Associação Genética , Cardiopatias Congênitas/genética , Deficiência Intelectual/genética , Proteína Fosfatase 1/genética , Adolescente , Adulto , Criança , Pré-Escolar , Exoma/genética , Feminino , Predisposição Genética para Doença , Cardiopatias Congênitas/fisiopatologia , Humanos , Deficiência Intelectual/fisiopatologia , Masculino , Mutação de Sentido Incorreto , Fosforilação/genética
16.
Am J Hum Genet ; 99(3): 728-734, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27545675

RESUMO

Via whole-exome sequencing, we identified six females from independent families with a common neurodevelopmental phenotype including developmental delay, intellectual disability, autism, hypotonia, and seizures, all with de novo predicted deleterious variants in the nuclear localization signal of Heterogeneous Nuclear Ribonucleoprotein H2, encoded by HNRNPH2, a gene located on the X chromosome. Many of the females also have seizures, psychiatric co-morbidities, and orthopedic, gastrointestinal, and growth problems as well as common dysmorphic facial features. HNRNPs are a large group of ubiquitous proteins that associate with pre-mRNAs in eukaryotic cells to produce a multitude of alternatively spliced mRNA products during development and play an important role in controlling gene expression. The failure to identify affected males, the severity of the neurodevelopmental phenotype in females, and the essential role of this gene suggests that male conceptuses with these variants may not be viable.


Assuntos
Cromossomos Humanos X/genética , Ribonucleoproteínas Nucleares Heterogêneas Grupo F-H/genética , Mutação/genética , Transtornos do Neurodesenvolvimento/genética , Sinais de Localização Nuclear , Caracteres Sexuais , Adulto , Processamento Alternativo/genética , Sequência de Aminoácidos , Animais , Transtorno Autístico/genética , Criança , Pré-Escolar , Deficiências do Desenvolvimento/genética , Perda do Embrião/genética , Exoma/genética , Face/anormalidades , Feminino , Frequência do Gene , Ribonucleoproteínas Nucleares Heterogêneas Grupo F-H/química , Humanos , Deficiência Intelectual/genética , Masculino , Microcefalia/genética , Hipotonia Muscular/genética , Fenótipo , Convulsões/genética
17.
Am J Hum Genet ; 98(6): 1235-1242, 2016 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-27259054

RESUMO

Whole-exome sequencing (WES) is increasingly being utilized to diagnose individuals with undiagnosed disorders. Developmental delay and short stature are common clinical indications for WES. We performed WES in three families, using proband-parent trios and two additional affected siblings. We identified a syndrome due to an autosomal-recessively inherited deficiency of transketolase, encoded by TKT, on chromosome 3p21. Our series includes three families with a total of five affected individuals, ranging in age from 4 to 25 years. Two families of Ashkenazi Jewish ancestry were homozygous for an 18 base pair in-frame insertion in TKT. The third family was compound heterozygous for nonsense and missense variants in TKT. All affected individuals had short stature and were developmentally delayed. Congenital heart defects were noted in four of the five affected individuals, and there was a history of chronic diarrhea and cataracts in the older individuals with the homozygous 18 base pair insertion. Enzymatic testing confirmed significantly reduced transketolase activity. Elevated urinary excretion of erythritol, arabitol, ribitol, and pent(ul)ose-5-phosphates was detected, as well as elevated amounts of erythritol, arabitol, and ribitol in the plasma of affected individuals. Transketolase deficiency reduces NADPH synthesis and nucleic acid synthesis and cell division and could explain the problems with growth. NADPH is also critical for maintaining cerebral glutathione, which might contribute to the neurodevelopmental delays. Transketolase deficiency is one of a growing list of inborn errors of metabolism in the non-oxidative part of the pentose phosphate pathway.


Assuntos
Deficiências do Desenvolvimento/etiologia , Nanismo/etiologia , Cardiopatias Congênitas/etiologia , Mutação/genética , Transcetolase/genética , Adulto , Criança , Pré-Escolar , Deficiências do Desenvolvimento/metabolismo , Deficiências do Desenvolvimento/patologia , Nanismo/metabolismo , Nanismo/patologia , Feminino , Glutationa/metabolismo , Cardiopatias Congênitas/metabolismo , Cardiopatias Congênitas/patologia , Humanos , Masculino , NADP/metabolismo , Linhagem , Síndrome , Adulto Jovem
18.
Cold Spring Harb Mol Case Stud ; 2(1): a000661, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27148580

RESUMO

We identified five unrelated individuals with significant global developmental delay and intellectual disability (ID), dysmorphic facial features and frequent microcephaly, and de novo predicted loss-of-function variants in chromosome alignment maintaining phosphoprotein 1 (CHAMP1). Our findings are consistent with recently reported de novo mutations in CHAMP1 in five other individuals with similar features. CHAMP1 is a zinc finger protein involved in kinetochore-microtubule attachment and is required for regulating the proper alignment of chromosomes during metaphase in mitosis. Mutations in CHAMP1 may affect cell division and hence brain development and function, resulting in developmental delay and ID.

19.
Am J Med Genet A ; 170(7): 1791-8, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27133397

RESUMO

Neurodevelopmental disorders (NDD) are common, with 1-3% of general population being affected, but the etiology is unknown in most individuals. Clinical whole-exome sequencing (WES) has proven to be a powerful tool for the identification of pathogenic variants leading to Mendelian disorders, among which NDD represent a significant percentage. Performing WES with a trio-approach has proven to be extremely effective in identifying de novo pathogenic variants as a common cause of NDD. Here we report six unrelated individuals with a common phenotype consisting of NDD with severe speech delay, hypotonia, and facial dysmorphism. These patients underwent WES with a trio approach and de novo heterozygous predicted pathogenic novel variants in the KAT6A gene were identified. The KAT6A gene encodes a histone acetyltransfrease protein and it has long been known for its structural involvement in acute myeloid leukemia; however, it has not previously been associated with any congenital disorder. In animal models the KAT6A ortholog is involved in transcriptional regulation during development. Given the similar findings in animal models and our patient's phenotypes, we hypothesize that KAT6A could play a role in development of the brain, face, and heart in humans. © 2016 Wiley Periodicals, Inc.


Assuntos
Exoma/genética , Histona Acetiltransferases/genética , Deficiência Intelectual/genética , Transtornos do Neurodesenvolvimento/genética , Adulto , Criança , Pré-Escolar , Feminino , Heterozigoto , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Deficiência Intelectual/fisiopatologia , Masculino , Mutação , Transtornos do Neurodesenvolvimento/fisiopatologia , Análise de Sequência de DNA
20.
Hum Genet ; 135(7): 699-705, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27048600

RESUMO

Whole exome sequencing (WES) can be used to efficiently identify de novo genetic variants associated with genetically heterogeneous conditions including intellectual disabilities. We have performed WES for 4102 (1847 female; 2255 male) intellectual disability/developmental delay cases and we report five patients with a neurodevelopmental disorder associated with developmental delay, intellectual disability, behavioral problems, hypotonia, speech problems, microcephaly, pachygyria and dysmorphic features in whom we have identified de novo missense and canonical splice site mutations in CSNK2A1, the gene encoding CK2α, the catalytic subunit of protein kinase CK2, a ubiquitous serine/threonine kinase composed of two regulatory (ß) and two catalytic (α and/or α') subunits. Somatic mutations in CSNK2A1 have been implicated in various cancers; however, this is the first study to describe a human condition associated with germline mutations in any of the CK2 subunits.


Assuntos
Transtornos Dismórficos Corporais/genética , Deficiência Intelectual/genética , Transtornos do Neurodesenvolvimento/genética , Adolescente , Transtornos Dismórficos Corporais/fisiopatologia , Caseína Quinase II/genética , Criança , Pré-Escolar , Exoma/genética , Feminino , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Deficiência Intelectual/patologia , Mutação , Transtornos do Neurodesenvolvimento/fisiopatologia
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