RESUMEN
Congenital afibrinogenemia is the most severe congenital fibrinogen disorder, characterized by undetectable fibrinogen in circulation. Causative mutations can be divided into two main classes: null mutations with no protein production at all and missense mutations producing abnormal protein chains that are retained inside the cell. The vast majority of cases are due to single base pair mutations or small insertions or deletions in the coding regions or intron-exon junctions of FGB, FGA and FGG. Only a few large rearrangements have been described, all deletions involving FGA. Here we report the characterization of a 403 bp duplication of the FGG exon 8-intron 8 junction accounting for congenital afibrinogenemia in a large consanguineous family from Turkey. This mutation, which had escaped detection by Sanger sequencing of short polymerase chain reaction (PCR) amplicons of coding sequences and splice sites, was identified by studying multiple alignments of reads obtained from whole exome sequencing of a heterozygous individual followed by PCR amplification and sequencing of a larger portion of FGG. Because the mutation duplicates the donor splice site of intron 8, we predicted that the impact of the mutation would be on FGG transcript splicing. Analysis of mRNA produced by cells transiently transfected with normal or mutant minigene constructs showed that the duplication causes production of several aberrant FGG transcripts generating premature truncating codons.
Asunto(s)
Afibrinogenemia , Afibrinogenemia/genética , Consanguinidad , Exones , Fibrinógeno , Humanos , Intrones , Mutación , TurquíaRESUMEN
Arthrogryposis describes the presence of multiple joint-contractures. Clinical severity of this phenotype is variable, and more than 400 causative genes have been proposed. Among these, ERGIC1 is a recently reported candidate encoding a putative transmembrane protein of the ER-Golgi interface. Two homozygous missense variants have been reported in patients with relatively mild non-syndromic arthrogryposis. In a consanguineous family with two affected siblings presenting congenital arthrogryposis and some facial dysmorphism we performed prenatal array-CGH, postnatal targeted exome and genome sequencing. Genome sequencing identified a homozygous 22.6 Kb deletion encompassing the promoter and first exon of ERGIC1. mRNA quantification showed the complete absence of ERGIC1 expression in the two affected siblings and a decrease in heterozygous parents. Our observations validate the pathogenic role of ERGIC1 in congenital arthrogryposis and demonstrate that complete loss of function causes a relatively mild phenotype. These findings will contribute to improve genetic counseling of ERGIC1 mutations.
Asunto(s)
Artrogriposis/genética , Proteínas de Transporte Vesicular/genética , Consanguinidad , Homocigoto , Humanos , Lactante , Mutación con Pérdida de Función , Pérdida de Heterocigocidad , Masculino , Regiones Promotoras Genéticas/genética , Análisis por Matrices de Proteínas , ARN Mensajero , Secuenciación del ExomaRESUMEN
BACKGROUND: Gain-of-function mutations in the GLUD1 gene, encoding for glutamate dehydrogenase (GDH), result in the hyperinsulinism/hyperammonemia HI/HA syndrome. HI/HA patients present with harmful hypoglycemia secondary to protein-induced HI and elevated plasma ammonia levels. These symptoms may be accompanied by seizures and mental retardation. GDH is a mitochondrial enzyme that catalyzes the oxidative deamination of glutamate to α-ketoglutarate, under allosteric regulations mediated by its inhibitor GTP and its activator ADP. The present study investigated the functional properties of the GDH-G446V variant (alias c.1496G > T, p.(Gly499Val) (NM_005271.4)) in patient-derived lymphoblastoid cells. RESULTS: The calculated energy barrier between the opened and closed state of the enzyme was 41% lower in GDH-G446V compared to wild-type GDH, pointing to altered allosteric regulation. Computational analysis indicated conformational changes of GDH-G446V in the antenna region that is crucial for allosteric regulators. Enzymatic activity measured in patient-derived lymphoblastoid cells showed impaired allosteric responses of GDH-G446V to both regulators GTP and ADP. In particular, as opposed to control lymphoblastoid cells, GDH-G446V cells were not responsive to GTP in the lower range of ADP concentrations. Assessment of the metabolic rate revealed higher mitochondrial respiration in response to GDH-dependent substrates in the GDH-G446V lymphoblastoid cells compared to control cells. This indicates a shift toward glutaminolysis for energy provision in cells carrying the GDH-G446V variant. CONCLUSIONS: Substitution of the small amino acid glycine for the hydrophobic branched-chain valine altered the allosteric sensitivity to both inhibitory action of GTP and activation by ADP, rendering cells metabolically responsive to glutamine.
Asunto(s)
Glutamato Deshidrogenasa/genética , Glutamato Deshidrogenasa/metabolismo , Guanosina Trifosfato/metabolismo , Hiperinsulinismo/patología , Linfocitos/patología , Mutación , Adulto , Regulación Alostérica , Estudios de Casos y Controles , Femenino , Glutamato Deshidrogenasa/química , Humanos , Hiperinsulinismo/genética , Recién Nacido , Linfocitos/metabolismo , Masculino , Persona de Mediana Edad , Conformación ProteicaRESUMEN
MECP2 duplication syndrome (MDS; OMIM 300260) is an X-linked neurodevelopmental disorder caused by nonrecurrent duplications of the Xq28 region involving the gene methyl-CpG-binding protein 2 (MECP2; OMIM 300005). The core phenotype of affected individuals includes infantile hypotonia, severe intellectual disability, very poor-to-absent speech, progressive spasticity, seizures, and recurrent infections. The condition is 100% penetrant in males, with observed variability in phenotypic expression within and between families. Features of MDS in individuals of African descent are not well known. Here, we describe a male patient from Cameroon, with MDS caused by an inherited 610 kb microduplication of Xq28 encompassing the genes MECP2, IRAK1, L1CAM, and SLC6A8. This report supplements the public data on MDS and contributes by highlighting the phenotype of this condition in affected individuals of African descent.
Asunto(s)
Cromosomas Humanos X , Duplicación de Gen , Discapacidad Intelectual Ligada al Cromosoma X/patología , Proteína 2 de Unión a Metil-CpG/genética , Camerún , Preescolar , Humanos , Masculino , Discapacidad Intelectual Ligada al Cromosoma X/genética , FenotipoRESUMEN
Intellectual disability (ID) and autism spectrum disorders are complex neurodevelopmental disorders occurring among all ethnic and socioeconomic groups. Pathogenic variants in the neurite extension and migration factor (NEXMIF) gene (formerly named KIAA2022) on the X chromosome are responsible for ID, autistic behavior, epilepsy, or dysmorphic features in males. Most affected females described had a milder phenotype or were asymptomatic obligate carriers. We report here for the first time mother-to-son transmission of a novel NEXMIF truncating variant without X-inactivation skewing in the blood. Truncating gene variant leads to symptomatic mother to severely affected son transmission. Our findings emphasize that NEXMIF sequencing should be strongly considered in patients with unexplained autism spectrum disorder, ID, and epilepsy, irrespective of gender. Such testing could increase our knowledge of the pathogenicity of NEXMIF variants and improve genetic counseling.
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Trastorno del Espectro Autista/genética , Secuencia de Bases , Epilepsia/genética , Discapacidad Intelectual/genética , Proteínas del Tejido Nervioso/genética , Eliminación de Secuencia , Adulto , Trastorno del Espectro Autista/diagnóstico , Trastorno del Espectro Autista/fisiopatología , Niño , Epilepsia/diagnóstico , Epilepsia/fisiopatología , Femenino , Expresión Génica , Hemicigoto , Heterocigoto , Humanos , Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/fisiopatología , Masculino , Herencia Materna , Linaje , Índice de Severidad de la Enfermedad , Inactivación del Cromosoma XRESUMEN
Trisomy 21 (T21), Down Syndrome (DS) is the most common genetic cause of dementia and intellectual disability. Modeling DS is beginning to yield pharmaceutical therapeutic interventions for amelioration of intellectual disability, which are currently being tested in clinical trials. DS is also a unique genetic system for investigation of pathological and protective mechanisms for accelerated ageing, neurodegeneration, dementia, cancer, and other important common diseases. New drugs could be identified and disease mechanisms better understood by establishment of well-controlled cell model systems. We have developed a first nonintegration-reprogrammed isogenic human induced pluripotent stem cell (iPSC) model of DS by reprogramming the skin fibroblasts from an adult individual with constitutional mosaicism for DS and separately cloning multiple isogenic T21 and euploid (D21) iPSC lines. Our model shows a very low number of reprogramming rearrangements as assessed by a high-resolution whole genome CGH-array hybridization, and it reproduces several cellular pathologies seen in primary human DS cells, as assessed by automated high-content microscopic analysis. Early differentiation shows an imbalance of the lineage-specific stem/progenitor cell compartments: T21 causes slower proliferation of neural and faster expansion of hematopoietic lineage. T21 iPSC-derived neurons show increased production of amyloid peptide-containing material, a decrease in mitochondrial membrane potential, and an increased number and abnormal appearance of mitochondria. Finally, T21-derived neurons show significantly higher number of DNA double-strand breaks than isogenic D21 controls. Our fully isogenic system therefore opens possibilities for modeling mechanisms of developmental, accelerated ageing, and neurodegenerative pathologies caused by T21.
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Envejecimiento/fisiología , Diferenciación Celular/fisiología , Síndrome de Down/genética , Células Madre Pluripotentes Inducidas/citología , Neuronas/citología , Animales , Células Cultivadas , Fibroblastos/citología , Humanos , Mitocondrias/genéticaRESUMEN
We describe a 6-month-old female with developmental delay, hypotonia, supernumerary nipples, and distinct craniofacial features. Postnatal chromosome analysis revealed an unbalanced karyotype involving a der (5) and array-CGH defined two unbalanced regions with partial 2.3 Mb deletion of 5q35.3 in combination with a large 19.5 Mb duplication of chromosome 10 from q25.3 to q26.3. Parental karyotyping analysis showed that the father was carrier of a balanced t(5;10)(q35;q25). Two cousins of the proband with similar facial features had the same unbalanced karyotype with presence of the der (5) inherited from the malsegregation of the familial translocation. Additionally, three siblings (two deceased and one abortion) manifested a more severe phenotype including congenital heart defect, cleft palate, and agenesis of the corpus callosum and were diagnosed with unbalanced karyotypes inherited from the familial balanced translocation.
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Anomalías Múltiples/diagnóstico , Anomalías Múltiples/genética , Duplicación Cromosómica , Cromosomas Humanos Par 10 , Bandeo Cromosómico , Cromosomas Humanos Par 5 , Hibridación Genómica Comparativa , Síndrome del Maullido del Gato , Facies , Femenino , Humanos , Lactante , Masculino , Linaje , Fenotipo , TrisomíaRESUMEN
Since ten years, the number of amniocenteses or chorionic villous sampling for maternal anxiety has decreased thanks to the first trimester screening of trisomy 21 by ultrasound and maternal serum analysis. Two new tools have recently revolutionized antenatal screening and diagnosis: Analysing fetal DNA in maternal blood for chromosomes 21, 18 and 13 in order to avoid invasive fetal sampling and genomic comparative hybridization in order to diagnose deletions or duplications not detected by conventional caryotyping. These new technologies are dedicated to high-risk pregnancies, and have limitations. They do not replace ultrasound or first trimester screening. Information and ethics are central in antenatal screening and diagnosis.
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Diagnóstico Prenatal/tendencias , Análisis Químico de la Sangre , Hibridación Genómica Comparativa , Femenino , Humanos , Cariotipificación/métodos , Cariotipificación/tendencias , Selección de Paciente , Embarazo/sangre , Diagnóstico Prenatal/métodosRESUMEN
AIMS OF THE STUDY: The European Society of Medical Oncology (ESMO) recommends that countries should have reference centres to provide adequate diagnosis and treatment of gestational trophoblastic disease. A trophoblastic disease centre in the French-speaking part of Switzerland was inaugurated in 2009. The objectives of this study were to report the activity of the centre during the last 10 years and analyse gestational trophoblastic disease outcomes. METHODS: This was a retrospective study with data collected from all cases of gestational trophoblastic disease referred to the centre from 2009 to 2018. All histological specimens as well as data for treatment and follow-up of gestational trophoblastic disease and neoplasia were reviewed. Clinical features, including age, prognostic score and International Federation of Gynecology and Obstetrics (FIGO) stages (in the case of gestational trophoblastic neoplasia), human chorionic gonadotropin (hCG) follow-up, treatment and outcome were reported. RESULTS: The centre registered 354 patients, and these patients presented 156 cases of partial hydatidiform moles, 163 cases of complete hydatidiform moles and 14 cases of gestational trophoblastic neoplasia. During follow-up, 35 gestational trophoblastic neoplasms were diagnosed after hCG persistence. After pathology review, the overall agreement rates between our centre and a participating provider hospital was 82%. Methotrexate was the first line of single-agent chemotherapy for most patients, with resistance rates of 23%. Multi-agent chemotherapy was used as first-line treatment for five patients. None of the patients followed up by the centre died from gestational trophoblastic disease. CONCLUSIONS: This study reflects the activity of the Swiss trophoblastic disease centre from the French-speaking part of Switzerland created in 2009, and its role as local and national reference centre, in terms of global health, for women with gestational trophoblastic disease.
Asunto(s)
Enfermedad Trofoblástica Gestacional , Mola Hidatiforme , Gonadotropina Coriónica , Femenino , Enfermedad Trofoblástica Gestacional/diagnóstico , Enfermedad Trofoblástica Gestacional/tratamiento farmacológico , Enfermedad Trofoblástica Gestacional/epidemiología , Humanos , Embarazo , Estudios Retrospectivos , Suiza/epidemiologíaRESUMEN
Turner syndrome, caused by partial or complete loss of one copy of X-chromosome (45,X), is the most common sex chromosome abnormality in women with an incidence of 1 in 2500 female births. Here, we report the generation and characterization of induced pluripotent stem cells (iPSCs) carrying X-monosomy anomaly, with isogenic control iPSCs. Among the iPSC lines generated from 46XX-fibroblasts, one spontaneously lost a copy of X-chromosome following the reprogramming process, establishing the 45X-iPSC line.
RESUMEN
Ongoing chromosomal instability in neoplasia (CIN) generates intratumor genomic heterogeneity and limits the efficiency of oncotherapeutics. Neoplastic human cells utilizing the alternative lengthening of telomeres (ALT)-pathway, display extensive structural and numerical CIN. To unravel patterns of genome evolution driven by oncogene-replication stress, telomere dysfunction, or genotoxic therapeutic interventions, we examined by comparative genomic hybridization five karyotypically-diverse outcomes of the ALT osteosarcoma cell line U2-OS. These results demonstrate a high tendency of the complex cancer genome to perpetuate specific genomic imbalances despite the karyotypic evolution, indicating an ongoing process of genome dosage maintenance. Molecular karyotyping in four ALT human cell lines showed that mitotic cells with low levels of random structural CIN display frequent evidence of whole genome doubling (WGD), suggesting that WGD may protect clonal chromosome aberrations from hypermutation. We tested this longstanding hypothesis in ALT cells exposed to gamma irradiation or to inducible DNA replication stress under overexpression of p21. Single-cell cytogenomic analyses revealed that although polyploidization promotes genomic heterogeneity, it also protects the complex cancer genome and hence confers genotoxic therapy resistance by generating identical extra copies of driver chromosomal aberrations, which can be spared in the process of tumor evolution if they undergo unstable or unfit rearrangements.
RESUMEN
Dermal fibroblasts isolated from an apparently healthy 50-year-old man were successfully transformed into induced pluripotent stem cells (iPSCs) by using the integration-free CytoTune-iPS Sendai Reprogramming method. The generated iPSC line has been expanded under feeder-free conditions and displayed all hallmarks of a standard pluripotent stem cell line such as a normal karyotype, expression of pluripotent factors and differentiation capacity into the three germ layers.
Asunto(s)
Células Madre Pluripotentes Inducidas , Diferenciación Celular , Reprogramación Celular , Fibroblastos , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Disorders/differences of sex development (DSD) cause profound psychological and reproductive consequences for the affected individuals, however, most are still unexplained at the molecular level. Here, we present a novel gene, 3-hydroxy-3-methylglutaryl coenzyme A synthase 2 (HMGCS2), encoding a metabolic enzyme in the liver important for energy production from fatty acids, that shows an unusual expression pattern in developing fetal mouse gonads. Shortly after gonadal sex determination it is up-regulated in the developing testes following a very similar spatial and temporal pattern as the male-determining gene Sry in Sertoli cells before switching to ovarian enriched expression. To test if Hmgcs2 is important for gonad development in mammals, we pursued two lines of investigations. Firstly, we generated Hmgcs2-null mice using CRISPR/Cas9 and found that these mice had gonads that developed normally even on a sensitized background. Secondly, we screened 46,XY DSD patients with gonadal dysgenesis and identified two unrelated patients with a deletion and a deleterious missense variant in HMGCS2 respectively. However, both variants were heterozygous, suggesting that HMGCS2 might not be the causative gene. Analysis of a larger number of patients in the future might shed more light into the possible association of HMGCS2 with human gonadal development.
Asunto(s)
Trastornos del Desarrollo Sexual/genética , Disgenesia Gonadal/genética , Gónadas/crecimiento & desarrollo , Hidroximetilglutaril-CoA Sintasa/genética , Adolescente , Animales , Trastornos del Desarrollo Sexual/patología , Femenino , Regulación del Desarrollo de la Expresión Génica/genética , Disgenesia Gonadal/patología , Gónadas/patología , Heterocigoto , Humanos , Masculino , Ratones , Mutación Missense/genética , Ovario/crecimiento & desarrollo , Ovario/patología , Células de Sertoli/metabolismo , Proteína de la Región Y Determinante del Sexo/genética , Testículo/crecimiento & desarrollo , Testículo/patologíaRESUMEN
Mucopolysaccharidosis type I-Hurler (MPS1-H) is the most severe form of inherited metabolic diseases caused by mutations in the IDUA gene. The resulting deficiency of alpha L-iduronidase enzyme leads to a progressive accumulation of glycosaminoglycans in lysosomes which damages multiple organs and highly reduces life expectancy of affected children. Skin fibroblasts of a 2-year-old MPS1-H male, carrying two mutations in each IDUA alleles (H358_T364del; W402X), were reprogrammed into induced pluripotent stem cells (iPSCs) using the CytoTune-iPS Sendai Reprogramming method applying Yamanaka-factors (OCT4, SOX2, KLF4, c-MYC). iPSCs expressed pluripotency transcription factors while iPSC-derived embryoid bodies reveal markers of the three germ layers.
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Diferenciación Celular , Fibroblastos/patología , Iduronidasa/genética , Células Madre Pluripotentes Inducidas/patología , Mucopolisacaridosis I/genética , Mucopolisacaridosis I/patología , Mutación , Células Cultivadas , Reprogramación Celular , Preescolar , Cuerpos Embrioides/metabolismo , Cuerpos Embrioides/patología , Fibroblastos/metabolismo , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Factor 4 Similar a Kruppel , MasculinoRESUMEN
Aneuploidy is a major source of gene dosage imbalance due to copy number alterations (CNA), and viable human trisomies are model disorders of altered gene expression. We study gene and allele-specific expression (ASE) of 9668 single-cell fibroblasts from trisomy 21 (T21) discordant twins and from mosaic T21, T18, T13 and T8. We examine 928 single cells with deep scRNAseq. Expected and observed overexpression of trisomic genes in trisomic vs. diploid bulk RNAseq is not detectable in trisomic vs. diploid single cells. Instead, for trisomic genes with low-to-average expression, their altered gene dosage is mainly due to the higher fraction of trisomic cells simultaneously expressing these genes, in agreement with a stochastic 2-state burst-like model of transcription. These results, confirmed in a further analysis of 8740 single fibroblasts with shallow scRNAseq, suggest that the specific transcriptional profile of each gene contributes to the phenotypic variability of trisomies. We propose an improved model to understand the effects of CNA and, generally, of gene regulation on gene dosage imbalance.
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Variaciones en el Número de Copia de ADN , Dosificación de Gen , Modelos Genéticos , Transcriptoma/genética , Trisomía/genética , Alelos , Cromosomas Humanos Par 13/genética , Cromosomas Humanos Par 18/genética , Cromosomas Humanos Par 8/genética , Síndrome de Down/genética , Femenino , Fibroblastos , Perfilación de la Expresión Génica , Humanos , Masculino , Mosaicismo , Fenotipo , RNA-Seq , Análisis de la Célula IndividualRESUMEN
BACKGROUND: Hirschsprung Disease (HSCR) is a congenital defect of the intestinal innervations characterized by complex inheritance. Many susceptibility genes including RET, the major HSCR gene, and several linked regions and associated loci have been shown to contribute to disease pathogenesis. Nonetheless, a proportion of patients still remains unexplained. Copy Number Variations (CNVs) have already been involved in HSCR, and for this reason we performed Comparative Genomic Hybridization (CGH), using a custom array with high density probes. RESULTS: A total of 20 HSCR candidate regions/genes was tested in 55 sporadic patients and four patients with already known chromosomal aberrations. Among 83 calls, 12 variants were experimentally validated, three of which involving the HSCR crucial genes SEMA3A/3D, NRG1, and PHOX2B. Conversely RET involvement in HSCR does not seem to rely on the presence of CNVs while, interestingly, several gains and losses did co-occur with another RET defect, thus confirming that more than one predisposing event is necessary for HSCR to develop. New loci were also shown to be involved, such as ALDH1A2, already found to play a major role in the enteric nervous system. Finally, all the inherited CNVs were of maternal origin. CONCLUSIONS: Our results confirm a wide genetic heterogeneity in HSCR occurrence and support a role of candidate genes in expression regulation and cell signaling, thus contributing to depict further the molecular complexity of the genomic regions involved in the Enteric Nervous System development. The observed maternal transmission bias for HSCR associated CNVs supports the hypothesis that in females these variants might be more tolerated, requiring additional alterations to develop HSCR disease.
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Variaciones en el Número de Copia de ADN/genética , Enfermedad de Hirschsprung/genética , Familia de Aldehído Deshidrogenasa 1/genética , Aberraciones Cromosómicas , Hibridación Genómica Comparativa , Femenino , Heterogeneidad Genética , Predisposición Genética a la Enfermedad , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Polimorfismo de Nucleótido Simple , Retinal-Deshidrogenasa/genéticaRESUMEN
There is emerging evidence for the involvement of reactive oxygen species (ROS) in the regulation of stem cells and cellular differentiation. Absence of the ROS-generating NADPH oxidase NOX2 in chronic granulomatous disease (CGD) patients, predominantly manifests as immune deficiency, but has also been associated with decreased cognition. Here, we investigate the role of NOX enzymes in neuronal homeostasis in adult mouse brain and in neural cells derived from human induced pluripotent stem cells (iPSC). High levels of NOX2 were found in mouse adult neurogenic regions. In NOX2-deficient mice, neurogenic regions showed diminished redox modifications, as well as decrease in neuroprecursor numbers and in expression of genes involved in neural differentiation including NES, BDNF and OTX2. iPSC from healthy subjects and patients with CGD were used to study the role of NOX2 in human in vitro neuronal development. Expression of NOX2 was low in undifferentiated iPSC, upregulated upon neural induction, and disappeared during neuronal differentiation. In human neurospheres, NOX2 protein and ROS generation were polarized within the inner cell layer of rosette structures. NOX2 deficiency in CGD-iPSCs resulted in an abnormal neural induction in vitro, as revealed by a reduced expression of neuroprogenitor markers (NES, BDNF, OTX2, NRSF/REST), and a decreased generation of mature neurons. Vector-mediated NOX2 expression in NOX2-deficient iPSCs rescued neurogenesis. Taken together, our study provides novel evidence for a regulatory role of NOX2 during early stages of neurogenesis in mouse and human.
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Encéfalo/citología , Enfermedad Granulomatosa Crónica/metabolismo , Células Madre Pluripotentes Inducidas/citología , NADPH Oxidasa 2/genética , Células-Madre Neurales/citología , Neurogénesis , Animales , Encéfalo/metabolismo , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Células Cultivadas , Enfermedad Granulomatosa Crónica/patología , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Ratones , NADPH Oxidasa 2/metabolismo , Nestina/genética , Nestina/metabolismo , Células-Madre Neurales/metabolismo , Factores de Transcripción Otx/genética , Factores de Transcripción Otx/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Proteínas Represoras/genética , Proteínas Represoras/metabolismoRESUMEN
Genetic generalized epilepsy (GGE), formerly known as idiopathic generalized epilepsy, is the most common form of epilepsy and is thought to have predominant genetic etiology. GGE are clinically characterized by absence, myoclonic, or generalized tonic-clonic seizures with electroencephalographic pattern of bilateral, synchronous, and symmetrical spike-and-wave discharges. Despite their strong heritability, the genetic basis of generalized epilepsies remains largely elusive. Nevertheless, recent advances in genetic technology have led to the identification of numerous genes and genomic defects in various types of epilepsies in the past few years. In the present study, we performed whole-exome sequencing in a family with GGE consistent with the diagnosis of eyelid myoclonia with absences. We found a nonsense variant (c.196C>T/p.(Arg66*)) in RORB, which encodes the beta retinoid-related orphan nuclear receptor (RORß), in four affected family members. In addition, two de novo variants (c.218T>C/p.(Leu73Pro); c.1249_1251delACG/p.(Thr417del)) were identified in sporadic patients by trio-based exome sequencing. We also found two de novo deletions in patients with behavioral and cognitive impairment and epilepsy: a 52-kb microdeletion involving exons 5-10 of RORB and a larger 9q21-microdeletion. Furthermore, we identified a patient with intellectual disability and a balanced translocation where one breakpoint truncates RORB and refined the phenotype of a recently reported patient with RORB deletion. Our data support the role of RORB gene variants/CNVs in neurodevelopmental disorders including epilepsy, and especially in generalized epilepsies with predominant absence seizures.
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Discapacidades del Desarrollo/genética , Epilepsia Generalizada/genética , Miembro 2 del Grupo F de la Subfamilia 1 de Receptores Nucleares/genética , Adulto , Niño , Puntos de Rotura del Cromosoma , Deleción Cromosómica , Codón sin Sentido , Discapacidades del Desarrollo/diagnóstico , Epilepsia Generalizada/diagnóstico , Exoma , Exones , Femenino , Humanos , Masculino , Linaje , Síndrome , Translocación GenéticaRESUMEN
Williams-Beuren syndrome (WBS) is a rare neurodevelopmental condition caused by a recurrent chromosomal microdeletion involving about 28 contiguous genes at 7q11.23. Most patients display a specific congenital heart defect, characteristic facial features, a particular behavior, and intellectual disability. Cases from sub-Saharan Africa have been seldom reported. The present study describes 3 Cameroonian patients affected by WBS, aged 19 months, 13 and 14 years, in whom the diagnosis was confirmed by fluorescent in situ hybridization (FISH) and comparative genomic hybridization (CGH). The first patient presented with a congenital heart defect, the second and third with learning difficulties as well as developmental and behavioral issues. In the latter 2 cases, the facial phenotypes were similar to those of the unaffected population with the same ethnic background. However, the cardiovascular anomalies and friendly behavioral attitudes led to suspicion of WBS. FISH revealed the deletion of the WBS critical region in the first patient, and array-CGH detected a heterozygous â¼1.4-Mb deletion in the 7q11.23 region in the second and third patient. This preliminary report suggests that for sub-Saharan Africans clinical suspicion of WBS could be mostly based on behavioral phenotype and structural heart defects, and less on the classical facial dysmorphic signs.