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1.
Mod Pathol ; 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31534204

RESUMO

We recently proposed that an epithelial renal tumor "papillary renal neoplasm with reverse polarity" represents a distinct entity. It constituted 4% of previously diagnosed papillary renal cell carcinoma at the participating institutions. Histologically, it is characterized by papillary or tubulopapillary architecture covered by a single layer of eosinophilic cells with finely granular cytoplasm and apically located nuclei. It is characteristically positive for GATA3 and L1CAM and lack vimentin and, to a lesser extent, α-methylacyl-CoA-racemase (AMACR/p504s) immunostaining. To investigate the molecular pathogenesis of these tumors, we performed targeted next-generation sequencing on ten previously reported papillary renal neoplasms with reverse polarity, followed by a targeted polymerase chain reaction analysis for KRAS mutations in a control series of 30 type 1 and 2 papillary renal cell carcinomas. KRAS missense mutations were identified in eight of ten papillary renal neoplasms with reverse polarity. These mutations were clustered in exon 2-codon 12: c.35 G > T (n = 6) or c.34 G > C (n = 2) resulting in p.Gly12Val and p.Gly12Arg alterations, respectively. One of the wild-type tumors had BRAF c.1798_1799delGTinsAG (p.Val600Arg) mutation. No KRAS mutations were identified in any of the 30 control tumors. In summary, this study supports our proposal that papillary renal neoplasm with reverse polarity is an entity distinct from papillary renal cell carcinoma and the only renal cell neoplasm to consistently harbor KRAS mutations.

2.
Ann Clin Transl Neurol ; 5(10): 1277-1285, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30349862

RESUMO

De novo variants in DDX3X account for 1-3% of unexplained intellectual disability (ID) cases and are amongst the most common causes of ID especially in females. Forty-seven patients (44 females, 3 males) have been described. We identified 31 additional individuals carrying 29 unique DDX3X variants, including 30 postnatal individuals with complex clinical presentations of developmental delay or ID, and one fetus with abnormal ultrasound findings. Rare or novel phenotypes observed include respiratory problems, congenital heart disease, skeletal muscle mitochondrial DNA depletion, and late-onset neurologic decline. Our findings expand the spectrum of DNA variants and phenotypes associated with DDX3X disorders.

3.
Am J Hum Genet ; 102(5): 985-994, 2018 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-29656860

RESUMO

N-alpha-acetylation is a common co-translational protein modification that is essential for normal cell function in humans. We previously identified the genetic basis of an X-linked infantile lethal Mendelian disorder involving a c.109T>C (p.Ser37Pro) missense variant in NAA10, which encodes the catalytic subunit of the N-terminal acetyltransferase A (NatA) complex. The auxiliary subunit of the NatA complex, NAA15, is the dimeric binding partner for NAA10. Through a genotype-first approach with whole-exome or genome sequencing (WES/WGS) and targeted sequencing analysis, we identified and phenotypically characterized 38 individuals from 33 unrelated families with 25 different de novo or inherited, dominantly acting likely gene disrupting (LGD) variants in NAA15. Clinical features of affected individuals with LGD variants in NAA15 include variable levels of intellectual disability, delayed speech and motor milestones, and autism spectrum disorder. Additionally, mild craniofacial dysmorphology, congenital cardiac anomalies, and seizures are present in some subjects. RNA analysis in cell lines from two individuals showed degradation of the transcripts with LGD variants, probably as a result of nonsense-mediated decay. Functional assays in yeast confirmed a deleterious effect for two of the LGD variants in NAA15. Further supporting a mechanism of haploinsufficiency, individuals with copy-number variant (CNV) deletions involving NAA15 and surrounding genes can present with mild intellectual disability, mild dysmorphic features, motor delays, and decreased growth. We propose that defects in NatA-mediated N-terminal acetylation (NTA) lead to variable levels of neurodevelopmental disorders in humans, supporting the importance of the NatA complex in normal human development.

5.
Am J Hum Genet ; 101(5): 716-724, 2017 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-29100085

RESUMO

DHX30 is a member of the family of DExH-box helicases, which use ATP hydrolysis to unwind RNA secondary structures. Here we identified six different de novo missense mutations in DHX30 in twelve unrelated individuals affected by global developmental delay (GDD), intellectual disability (ID), severe speech impairment and gait abnormalities. While four mutations are recurrent, two are unique with one affecting the codon of one recurrent mutation. All amino acid changes are located within highly conserved helicase motifs and were found to either impair ATPase activity or RNA recognition in different in vitro assays. Moreover, protein variants exhibit an increased propensity to trigger stress granule (SG) formation resulting in global translation inhibition. Thus, our findings highlight the prominent role of translation control in development and function of the central nervous system and also provide molecular insight into how DHX30 dysfunction might cause a neurodevelopmental disorder.


Assuntos
Deficiências do Desenvolvimento/genética , Mutação de Sentido Incorreto/genética , RNA Helicases/genética , Adenosina Trifosfatases/genética , Adolescente , Aminoácidos/genética , Linhagem Celular , Linhagem Celular Tumoral , Sistema Nervoso Central/patologia , Criança , Pré-Escolar , Feminino , Células HEK293 , Humanos , Deficiência Intelectual/genética , Masculino , RNA/genética
6.
PLoS Genet ; 13(7): e1006905, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28742085

RESUMO

Dominant mutations in CACNA1A, encoding the α-1A subunit of the neuronal P/Q type voltage-dependent Ca2+ channel, can cause diverse neurological phenotypes. Rare cases of markedly severe early onset developmental delay and congenital ataxia can be due to de novo CACNA1A missense alleles, with variants affecting the S4 transmembrane segments of the channel, some of which are reported to be loss-of-function. Exome sequencing in five individuals with severe early onset ataxia identified one novel variant (p.R1673P), in a girl with global developmental delay and progressive cerebellar atrophy, and a recurrent, de novo p.R1664Q variant, in four individuals with global developmental delay, hypotonia, and ophthalmologic abnormalities. Given the severity of these phenotypes we explored their functional impact in Drosophila. We previously generated null and partial loss-of-function alleles of cac, the homolog of CACNA1A in Drosophila. Here, we created transgenic wild type and mutant genomic rescue constructs with the two noted conserved point mutations. The p.R1673P mutant failed to rescue cac lethality, displayed a gain-of-function phenotype in electroretinograms (ERG) recorded from mutant clones, and evolved a neurodegenerative phenotype in aging flies, based on ERGs and transmission electron microscopy. In contrast, the p.R1664Q variant exhibited loss of function and failed to develop a neurodegenerative phenotype. Hence, the novel R1673P allele produces neurodegenerative phenotypes in flies and human, likely due to a toxic gain of function.


Assuntos
Alelos , Canais de Cálcio/genética , Ataxia Cerebelar/genética , Genoma Humano , Doenças Neurodegenerativas/genética , Animais , Animais Geneticamente Modificados , Ataxia Cerebelar/diagnóstico por imagem , Criança , Pré-Escolar , Drosophila melanogaster/genética , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Microscopia Eletrônica de Transmissão , Mutação de Sentido Incorreto , Neuroimagem , Fenótipo , Mutação Puntual
7.
Genome Med ; 9(1): 26, 2017 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-28327206

RESUMO

BACKGROUND: Given the rarity of most single-gene Mendelian disorders, concerted efforts of data exchange between clinical and scientific communities are critical to optimize molecular diagnosis and novel disease gene discovery. METHODS: We designed and implemented protocols for the study of cases for which a plausible molecular diagnosis was not achieved in a clinical genomics diagnostic laboratory (i.e. unsolved clinical exomes). Such cases were recruited to a research laboratory for further analyses, in order to potentially: (1) accelerate novel disease gene discovery; (2) increase the molecular diagnostic yield of whole exome sequencing (WES); and (3) gain insight into the genetic mechanisms of disease. Pilot project data included 74 families, consisting mostly of parent-offspring trios. Analyses performed on a research basis employed both WES from additional family members and complementary bioinformatics approaches and protocols. RESULTS: Analysis of all possible modes of Mendelian inheritance, focusing on both single nucleotide variants (SNV) and copy number variant (CNV) alleles, yielded a likely contributory variant in 36% (27/74) of cases. If one includes candidate genes with variants identified within a single family, a potential contributory variant was identified in a total of ~51% (38/74) of cases enrolled in this pilot study. The molecular diagnosis was achieved in 30/63 trios (47.6%). Besides this, the analysis workflow yielded evidence for pathogenic variants in disease-associated genes in 4/6 singleton cases (66.6%), 1/1 multiplex family involving three affected siblings, and 3/4 (75%) quartet families. Both the analytical pipeline and the collaborative efforts between the diagnostic and research laboratories provided insights that allowed recent disease gene discoveries (PURA, TANGO2, EMC1, GNB5, ATAD3A, and MIPEP) and increased the number of novel genes, defined in this study as genes identified in more than one family (DHX30 and EBF3). CONCLUSION: An efficient genomics pipeline in which clinical sequencing in a diagnostic laboratory is followed by the detailed reanalysis of unsolved cases in a research environment, supplemented with WES data from additional family members, and subject to adjuvant bioinformatics analyses including relaxed variant filtering parameters in informatics pipelines, can enhance the molecular diagnostic yield and provide mechanistic insights into Mendelian disorders. Implementing these approaches requires collaborative clinical molecular diagnostic and research efforts.


Assuntos
Biologia Computacional/métodos , Variações do Número de Cópias de DNA , Doenças Genéticas Inatas/diagnóstico , Genômica/métodos , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA/métodos , ATPases Associadas a Diversas Atividades Celulares , Adenosina Trifosfatases/genética , Proteínas de Ligação a DNA/genética , Exoma , Feminino , Subunidades beta da Proteína de Ligação ao GTP/genética , Doenças Genéticas Inatas/genética , Doenças Genéticas Inatas/metabolismo , Humanos , Masculino , Proteínas de Membrana/genética , Metaloendopeptidases/genética , Proteínas Mitocondriais/genética , Projetos Piloto , Fatores de Transcrição/genética
8.
Nucleic Acids Res ; 45(4): 1633-1648, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-27980096

RESUMO

We developed an algorithm, HMZDelFinder, that uses whole exome sequencing (WES) data to identify rare and intragenic homozygous and hemizygous (HMZ) deletions that may represent complete loss-of-function of the indicated gene. HMZDelFinder was applied to 4866 samples in the Baylor-Hopkins Center for Mendelian Genomics (BHCMG) cohort and detected 773 HMZ deletion calls (567 homozygous or 206 hemizygous) with an estimated sensitivity of 86.5% (82% for single-exonic and 88% for multi-exonic calls) and precision of 78% (53% single-exonic and 96% for multi-exonic calls). Out of 773 HMZDelFinder-detected deletion calls, 82 were subjected to array comparative genomic hybridization (aCGH) and/or breakpoint PCR and 64 were confirmed. These include 18 single-exon deletions out of which 8 were exclusively detected by HMZDelFinder and not by any of seven other CNV detection tools examined. Further investigation of the 64 validated deletion calls revealed at least 15 pathogenic HMZ deletions. Of those, 7 accounted for 17-50% of pathogenic CNVs in different disease cohorts where 7.1-11% of the molecular diagnosis solved rate was attributed to CNVs. In summary, we present an algorithm to detect rare, intragenic, single-exon deletion CNVs using WES data; this tool can be useful for disease gene discovery efforts and clinical WES analyses.


Assuntos
Biologia Computacional/métodos , Variações do Número de Cópias de DNA , Exoma , Doenças Genéticas Inatas/genética , Hemizigoto , Sequenciamento de Nucleotídeos em Larga Escala , Homozigoto , Algoritmos , Processamento Alternativo , Estudos de Coortes , Consanguinidade , Conjuntos de Dados como Assunto , Doenças Genéticas Inatas/diagnóstico , Humanos , Padrões de Herança , Modelos Genéticos , Linhagem , Reprodutibilidade dos Testes , Deleção de Sequência , Fluxo de Trabalho
9.
Am J Hum Genet ; 100(1): 117-127, 2017 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-28017373

RESUMO

From a GeneMatcher-enabled international collaboration, we identified ten individuals affected by intellectual disability, speech delay, ataxia, and facial dysmorphism and carrying a deleterious EBF3 variant detected by whole-exome sequencing. One 9-bp duplication and one splice-site, five missense, and two nonsense variants in EBF3 were found; the mutations occurred de novo in eight individuals, and the missense variant c.625C>T (p.Arg209Trp) was inherited by two affected siblings from their healthy mother, who is mosaic. EBF3 belongs to the early B cell factor family (also known as Olf, COE, or O/E) and is a transcription factor involved in neuronal differentiation and maturation. Structural assessment predicted that the five amino acid substitutions have damaging effects on DNA binding of EBF3. Transient expression of EBF3 mutant proteins in HEK293T cells revealed mislocalization of all but one mutant in the cytoplasm, as well as nuclear localization. By transactivation assays, all EBF3 mutants showed significantly reduced or no ability to activate transcription of the reporter gene CDKN1A, and in situ subcellular fractionation experiments demonstrated that EBF3 mutant proteins were less tightly associated with chromatin. Finally, in RNA-seq and ChIP-seq experiments, EBF3 acted as a transcriptional regulator, and mutant EBF3 had reduced genome-wide DNA binding and gene-regulatory activity. Our findings demonstrate that variants disrupting EBF3-mediated transcriptional regulation cause intellectual disability and developmental delay and are present in ∼0.1% of individuals with unexplained neurodevelopmental disorders.


Assuntos
Ataxia/genética , Face/anormalidades , Deficiência Intelectual/genética , Transtornos do Desenvolvimento da Linguagem/genética , Mutação , Transtornos do Neurodesenvolvimento/genética , Fatores de Transcrição/genética , Transcrição Genética/genética , Adolescente , Adulto , Substituição de Aminoácidos , Criança , Pré-Escolar , Cromatina/genética , Cromatina/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/genética , Deficiências do Desenvolvimento/genética , Exoma/genética , Feminino , Regulação da Expressão Gênica/genética , Genes Reporter , Células HEK293 , Humanos , Masculino , Modelos Moleculares , Mosaicismo , Transporte Proteico/genética , Síndrome , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
10.
Genome Med ; 8(1): 106, 2016 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-27799064

RESUMO

BACKGROUND: Mitochondrial presequence proteases perform fundamental functions as they process about 70 % of all mitochondrial preproteins that are encoded in the nucleus and imported posttranslationally. The mitochondrial intermediate presequence protease MIP/Oct1, which carries out precursor processing, has not yet been established to have a role in human disease. METHODS: Whole exome sequencing was performed on four unrelated probands with left ventricular non-compaction (LVNC), developmental delay (DD), seizures, and severe hypotonia. Proposed pathogenic variants were confirmed by Sanger sequencing or array comparative genomic hybridization. Functional analysis of the identified MIP variants was performed using the model organism Saccharomyces cerevisiae as the protein and its functions are highly conserved from yeast to human. RESULTS: Biallelic single nucleotide variants (SNVs) or copy number variants (CNVs) in MIPEP, which encodes MIP, were present in all four probands, three of whom had infantile/childhood death. Two patients had compound heterozygous SNVs (p.L582R/p.L71Q and p.E602*/p.L306F) and one patient from a consanguineous family had a homozygous SNV (p.K343E). The fourth patient, identified through the GeneMatcher tool, a part of the Matchmaker Exchange Project, was found to have inherited a paternal SNV (p.H512D) and a maternal CNV (1.4-Mb deletion of 13q12.12) that includes MIPEP. All amino acids affected in the patients' missense variants are highly conserved from yeast to human and therefore S. cerevisiae was employed for functional analysis (for p.L71Q, p.L306F, and p.K343E). The mutations p.L339F (human p.L306F) and p.K376E (human p.K343E) resulted in a severe decrease of Oct1 protease activity and accumulation of non-processed Oct1 substrates and consequently impaired viability under respiratory growth conditions. The p.L83Q (human p.L71Q) failed to localize to the mitochondria. CONCLUSIONS: Our findings reveal for the first time the role of the mitochondrial intermediate peptidase in human disease. Loss of MIP function results in a syndrome which consists of LVNC, DD, seizures, hypotonia, and cataracts. Our approach highlights the power of data exchange and the importance of an interrelationship between clinical and research efforts for disease gene discovery.


Assuntos
Genes Recessivos/genética , Cardiopatias Congênitas/etiologia , Metaloendopeptidases/genética , Hipotonia Muscular/etiologia , Morte Súbita do Lactente/etiologia , Adulto , Sequência de Aminoácidos , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Linhagem , Fenótipo , Homologia de Sequência de Aminoácidos , Síndrome
11.
Am J Hum Genet ; 99(4): 831-845, 2016 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-27640307

RESUMO

ATPase family AAA-domain containing protein 3A (ATAD3A) is a nuclear-encoded mitochondrial membrane protein implicated in mitochondrial dynamics, nucleoid organization, protein translation, cell growth, and cholesterol metabolism. We identified a recurrent de novo ATAD3A c.1582C>T (p.Arg528Trp) variant by whole-exome sequencing (WES) in five unrelated individuals with a core phenotype of global developmental delay, hypotonia, optic atrophy, axonal neuropathy, and hypertrophic cardiomyopathy. We also describe two families with biallelic variants in ATAD3A, including a homozygous variant in two siblings, and biallelic ATAD3A deletions mediated by nonallelic homologous recombination (NAHR) between ATAD3A and gene family members ATAD3B and ATAD3C. Tissue-specific overexpression of borR534W, the Drosophila mutation homologous to the human c.1582C>T (p.Arg528Trp) variant, resulted in a dramatic decrease in mitochondrial content, aberrant mitochondrial morphology, and increased autophagy. Homozygous null bor larvae showed a significant decrease of mitochondria, while overexpression of borWT resulted in larger, elongated mitochondria. Finally, fibroblasts of an affected individual exhibited increased mitophagy. We conclude that the p.Arg528Trp variant functions through a dominant-negative mechanism that results in small mitochondria that trigger mitophagy, resulting in a reduction in mitochondrial content. ATAD3A variation represents an additional link between mitochondrial dynamics and recognizable neurological syndromes, as seen with MFN2, OPA1, DNM1L, and STAT2 mutations.


Assuntos
Adenosina Trifosfatases/genética , Alelos , Proteínas de Membrana/genética , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Proteínas Mitocondriais/genética , Mutação , Doenças do Sistema Nervoso/genética , ATPases Associadas a Diversas Atividades Celulares , Adulto , Animais , Axônios/patologia , Cardiomiopatias/genética , Criança , Pré-Escolar , Variações do Número de Cópias de DNA/genética , Deficiências do Desenvolvimento/genética , Drosophila melanogaster/genética , Feminino , Fibroblastos , Homozigoto , Humanos , Lactente , Recém-Nascido , Masculino , Hipotonia Muscular/genética , Músculos/patologia , Doenças do Sistema Nervoso/metabolismo , Doenças do Sistema Nervoso/patologia , Neurônios/patologia , Atrofia Óptica/genética , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Síndrome , Adulto Jovem
12.
Am J Hum Genet ; 99(4): 886-893, 2016 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-27616478

RESUMO

Disruption of the establishment of left-right (L-R) asymmetry leads to situs anomalies ranging from situs inversus totalis (SIT) to situs ambiguus (heterotaxy). The genetic causes of laterality defects in humans are highly heterogeneous. Via whole-exome sequencing (WES), we identified homozygous mutations in PKD1L1 from three affected individuals in two unrelated families. PKD1L1 encodes a polycystin-1-like protein and its loss of function is known to cause laterality defects in mouse and medaka fish models. Family 1 had one fetus and one deceased child with heterotaxy and complex congenital heart malformations. WES identified a homozygous splicing mutation, c.6473+2_6473+3delTG, which disrupts the invariant splice donor site in intron 42, in both affected individuals. In the second family, a homozygous c.5072G>C (p.Cys1691Ser) missense mutation was detected in an individual with SIT and congenital heart disease. The p.Cys1691Ser substitution affects a highly conserved cysteine residue and is predicted by molecular modeling to disrupt a disulfide bridge essential for the proper folding of the G protein-coupled receptor proteolytic site (GPS) motif. Damaging effects associated with substitutions of this conserved cysteine residue in the GPS motif have also been reported in other genes, namely GPR56, BAI3, and PKD1 in human and lat-1 in C. elegans, further supporting the likely pathogenicity of p.Cys1691Ser in PKD1L1. The identification of bi-allelic PKD1L1 mutations recapitulates previous findings regarding phenotypic consequences of loss of function of the orthologous genes in mice and medaka fish and further expands our understanding of genetic contributions to laterality defects in humans.


Assuntos
Alelos , Lateralidade Funcional/genética , Proteínas de Membrana/genética , Mutação , Situs Inversus/genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Animais , Caenorhabditis elegans/genética , Cisteína/genética , Exoma/genética , Feminino , Doenças Fetais/genética , Cardiopatias Congênitas/genética , Síndrome de Heterotaxia , Homozigoto , Humanos , Recém-Nascido , Íntrons/genética , Masculino , Proteínas de Membrana/química , Camundongos , Pessoa de Meia-Idade , Modelos Moleculares , Mutação de Sentido Incorreto , Oryzias/genética , Linhagem , Processamento de RNA/genética
14.
Am J Hum Genet ; 99(3): 704-710, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27523599

RESUMO

GNB5 encodes the G protein ß subunit 5 and is involved in inhibitory G protein signaling. Here, we report mutations in GNB5 that are associated with heart-rate disturbance, eye disease, intellectual disability, gastric problems, hypotonia, and seizures in nine individuals from six families. We observed an association between the nature of the variants and clinical severity; individuals with loss-of-function alleles had more severe symptoms, including substantial developmental delay, speech defects, severe hypotonia, pathological gastro-esophageal reflux, retinal disease, and sinus-node dysfunction, whereas related heterozygotes harboring missense variants presented with a clinically milder phenotype. Zebrafish gnb5 knockouts recapitulated the phenotypic spectrum of affected individuals, including cardiac, neurological, and ophthalmological abnormalities, supporting a direct role of GNB5 in the control of heart rate, hypotonia, and vision.


Assuntos
Bradicardia/genética , Bradicardia/fisiopatologia , Deficiências do Desenvolvimento/genética , Subunidades beta da Proteína de Ligação ao GTP/genética , Genes Recessivos/genética , Mutação/genética , Nó Sinoatrial/fisiopatologia , Adolescente , Animais , Criança , Deficiências do Desenvolvimento/fisiopatologia , Feminino , Subunidades beta da Proteína de Ligação ao GTP/deficiência , Refluxo Gastroesofágico/genética , Refluxo Gastroesofágico/fisiopatologia , Deleção de Genes , Frequência Cardíaca/genética , Heterozigoto , Humanos , Masculino , Hipotonia Muscular/genética , Mutação de Sentido Incorreto/genética , Linhagem , Fenótipo , Doenças Retinianas/genética , Doenças Retinianas/fisiopatologia , Convulsões/genética , Síndrome , Adulto Jovem , Peixe-Zebra/genética , Peixe-Zebra/fisiologia
15.
Am J Hum Genet ; 98(3): 562-570, 2016 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-26942288

RESUMO

The paradigm of a single gene associated with one specific phenotype and mode of inheritance has been repeatedly challenged. Genotype-phenotype correlations can often be traced to different mutation types, localization of the variants in distinct protein domains, or the trigger of or escape from nonsense-mediated decay. Using whole-exome sequencing, we identified homozygous variants in EMC1 that segregated with a phenotype of developmental delay, hypotonia, scoliosis, and cerebellar atrophy in three families. In addition, a de novo heterozygous EMC1 variant was seen in an individual with a similar clinical and MRI imaging phenotype. EMC1 encodes a member of the endoplasmic reticulum (ER)-membrane protein complex (EMC), an evolutionarily conserved complex that has been proposed to have multiple roles in ER-associated degradation, ER-mitochondria tethering, and proper assembly of multi-pass transmembrane proteins. Perturbations of protein folding and organelle crosstalk have been implicated in neurodegenerative processes including cerebellar atrophy. We propose EMC1 as a gene in which either biallelic or monoallelic variants might lead to a syndrome including intellectual disability and preferential degeneration of the cerebellum.


Assuntos
Atrofia/genética , Deficiências do Desenvolvimento/genética , Variação Genética , Hipotonia Muscular/genética , Proteínas/genética , Escoliose/genética , Adolescente , Alelos , Sequência de Aminoácidos , Atrofia/diagnóstico , Cerebelo/patologia , Criança , Pré-Escolar , Deficiências do Desenvolvimento/diagnóstico , Degradação Associada com o Retículo Endoplasmático , Feminino , Estudos de Associação Genética , Heterozigoto , Humanos , Imagem por Ressonância Magnética , Masculino , Dados de Sequência Molecular , Hipotonia Muscular/diagnóstico , Mutação , Linhagem , Dobramento de Proteína , Proteínas/metabolismo , Escoliose/diagnóstico
16.
Am J Hum Genet ; 98(2): 347-57, 2016 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-26805781

RESUMO

The underlying genetic etiology of rhabdomyolysis remains elusive in a significant fraction of individuals presenting with recurrent metabolic crises and muscle weakness. Using exome sequencing, we identified bi-allelic mutations in TANGO2 encoding transport and Golgi organization 2 homolog (Drosophila) in 12 subjects with episodic rhabdomyolysis, hypoglycemia, hyperammonemia, and susceptibility to life-threatening cardiac tachyarrhythmias. A recurrent homozygous c.460G>A (p.Gly154Arg) mutation was found in four unrelated individuals of Hispanic/Latino origin, and a homozygous ∼34 kb deletion affecting exons 3-9 was observed in two families of European ancestry. One individual of mixed Hispanic/European descent was found to be compound heterozygous for c.460G>A (p.Gly154Arg) and the deletion of exons 3-9. Additionally, a homozygous exons 4-6 deletion was identified in a consanguineous Middle Eastern Arab family. No homozygotes have been reported for these changes in control databases. Fibroblasts derived from a subject with the recurrent c.460G>A (p.Gly154Arg) mutation showed evidence of increased endoplasmic reticulum stress and a reduction in Golgi volume density in comparison to control. Our results show that the c.460G>A (p.Gly154Arg) mutation and the exons 3-9 heterozygous deletion in TANGO2 are recurrent pathogenic alleles present in the Latino/Hispanic and European populations, respectively, causing considerable morbidity in the homozygotes in these populations.


Assuntos
Arritmias Cardíacas/genética , Debilidade Muscular/genética , Rabdomiólise/genética , Alelos , Árabes/genética , Arritmias Cardíacas/diagnóstico , Sequência de Bases , Criança , Pré-Escolar , Estresse do Retículo Endoplasmático/genética , Grupo com Ancestrais do Continente Europeu/genética , Exoma , Éxons , Feminino , Deleção de Genes , Complexo de Golgi/genética , Complexo de Golgi/metabolismo , Hispano-Americanos/genética , Homozigoto , Humanos , Lactente , Masculino , Dados de Sequência Molecular , Debilidade Muscular/diagnóstico , Linhagem , Rabdomiólise/diagnóstico
17.
Am J Hum Genet ; 97(6): 904-13, 2015 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-26637980

RESUMO

Meier-Gorlin syndrome (MGS) is a genetically heterogeneous primordial dwarfism syndrome known to be caused by biallelic loss-of-function mutations in one of five genes encoding pre-replication complex proteins: ORC1, ORC4, ORC6, CDT1, and CDC6. Mutations in these genes cause disruption of the origin of DNA replication initiation. To date, only an autosomal-recessive inheritance pattern has been described in individuals with this disorder, with a molecular etiology established in about three-fourths of cases. Here, we report three subjects with MGS and de novo heterozygous mutations in the 5' end of GMNN, encoding the DNA replication inhibitor geminin. We identified two truncating mutations in exon 2 (the 1(st) coding exon), c.16A>T (p.Lys6(∗)) and c.35_38delTCAA (p.Ile12Lysfs(∗)4), and one missense mutation, c.50A>G (p.Lys17Arg), affecting the second-to-last nucleotide of exon 2 and possibly RNA splicing. Geminin is present during the S, G2, and M phases of the cell cycle and is degraded during the metaphase-anaphase transition by the anaphase-promoting complex (APC), which recognizes the destruction box sequence near the 5' end of the geminin protein. All three GMNN mutations identified alter sites 5' to residue Met28 of the protein, which is located within the destruction box. We present data supporting a gain-of-function mechanism, in which the GMNN mutations result in proteins lacking the destruction box and hence increased protein stability and prolonged inhibition of replication leading to autosomal-dominant MGS.


Assuntos
Microtia Congênita/genética , Nanismo/genética , Geminina/genética , Transtornos do Crescimento/genética , Micrognatismo/genética , Mutação , Patela/anormalidades , Adolescente , Sequência de Aminoácidos , Sequência de Bases , Ciclo Celular/genética , Pré-Escolar , Microtia Congênita/metabolismo , Nanismo/metabolismo , Nanismo/patologia , Éxons , Feminino , Geminina/metabolismo , Expressão Gênica , Genes Dominantes , Transtornos do Crescimento/metabolismo , Heterozigoto , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Padrões de Herança , Masculino , Micrognatismo/metabolismo , Dados de Sequência Molecular , Patela/metabolismo , Linhagem , Estabilidade Proteica , Proteólise , Processamento de RNA , Alinhamento de Sequência
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