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Bramswig NC, Lüdecke HJ, Hamdan FF, Altmüller J, Beleggia F, Elcioglu NH, Freyer C, Gerkes EH, Demirkol YK, Knupp KG, Kuechler A, Li Y, Lowenstein DH, Michaud JL, Park K, Stegmann APA, Veenstra-Knol HE, Wieland T, Wollnik B, Engels H, Strom TM, Kleefstra T, Wieczorek D. Heterozygous HNRNPU variants cause early onset epilepsy and severe intellectual disability. Hum Genet 2017; 136:821-834. [PMID: 28393272 DOI: 10.1007/s00439-017-1795-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 04/06/2017] [Indexed: 11/25/2022]
Abstract
Pathogenic variants in genes encoding subunits of the spliceosome are the cause of several human diseases, such as neurodegenerative diseases. The RNA splicing process is facilitated by the spliceosome, a large RNA-protein complex consisting of small nuclear ribonucleoproteins (snRNPs), and many other proteins, such as heterogeneous nuclear ribonucleoproteins (hnRNPs). The HNRNPU gene (OMIM *602869) encodes the heterogeneous nuclear ribonucleoprotein U, which plays a crucial role in mammalian development. HNRNPU is expressed in the fetal brain and adult heart, kidney, liver, brain, and cerebellum. Microdeletions in the 1q44 region encompassing HNRNPU have been described in patients with intellectual disability (ID) and other clinical features, such as seizures, corpus callosum abnormalities (CCA), and microcephaly. Recently, pathogenic HNRNPU variants were identified in large ID and epileptic encephalopathy cohorts. In this study, we provide detailed clinical information of five novels and review two of the previously published individuals with (likely) pathogenic de novo variants in the HNRNPU gene including three non-sense and two missense variants, one small intragenic deletion, and one duplication. The phenotype in individuals with variants in HNRNPU is characterized by early onset seizures (6/7), severe ID (6/6), severe speech impairment (6/6), hypotonia (6/7), and central nervous system (CNS) (5/6), cardiac (4/6), and renal abnormalities (3/4). In this study, we broaden the clinical and mutational HNRNPU-associated spectrum, and demonstrate that heterozygous HNRNPU variants cause epilepsy, severe ID with striking speech impairment and variable CNS, cardiac, and renal anomalies.
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Wiessner M, Roos A, Munn CJ, Viswanathan R, Whyte T, Cox D, Schoser B, Sewry C, Roper H, Phadke R, Marini Bettolo C, Barresi R, Charlton R, Bönnemann CG, Abath Neto O, Reed UC, Zanoteli E, Araújo Martins Moreno C, Ertl-Wagner B, Stucka R, De Goede C, Borges da Silva T, Hathazi D, Dell’Aica M, Zahedi RP, Thiele S, Müller J, Kingston H, Müller S, Curtis E, Walter MC, Strom TM, Straub V, Bushby K, Muntoni F, Swan LE, Lochmüller H, Senderek J. Mutations in INPP5K, Encoding a Phosphoinositide 5-Phosphatase, Cause Congenital Muscular Dystrophy with Cataracts and Mild Cognitive Impairment. Am J Hum Genet 2017; 100:523-536. [PMID: 28190456 PMCID: PMC5339217 DOI: 10.1016/j.ajhg.2017.01.024] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/12/2017] [Indexed: 12/26/2022] Open
Abstract
Phosphoinositides are small phospholipids that control diverse cellular downstream signaling events. Their spatial and temporal availability is tightly regulated by a set of specific lipid kinases and phosphatases. Congenital muscular dystrophies are hereditary disorders characterized by hypotonia and weakness from birth with variable eye and central nervous system involvement. In individuals exhibiting congenital muscular dystrophy, early-onset cataracts, and mild intellectual disability but normal cranial magnetic resonance imaging, we identified bi-allelic mutations in INPP5K, encoding inositol polyphosphate-5-phosphatase K. Mutations impaired phosphatase activity toward the phosphoinositide phosphatidylinositol (4,5)-bisphosphate or altered the subcellular localization of INPP5K. Downregulation of INPP5K orthologs in zebrafish embryos disrupted muscle fiber morphology and resulted in abnormal eye development. These data link congenital muscular dystrophies to defective phosphoinositide 5-phosphatase activity that is becoming increasingly recognized for its role in mediating pivotal cellular mechanisms contributing to disease.
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Reuter MS, Tawamie H, Buchert R, Hosny Gebril O, Froukh T, Thiel C, Uebe S, Ekici AB, Krumbiegel M, Zweier C, Hoyer J, Eberlein K, Bauer J, Scheller U, Strom TM, Hoffjan S, Abdelraouf ER, Meguid NA, Abboud A, Al Khateeb MA, Fakher M, Hamdan S, Ismael A, Muhammad S, Abdallah E, Sticht H, Wieczorek D, Reis A, Abou Jamra R. Diagnostic Yield and Novel Candidate Genes by Exome Sequencing in 152 Consanguineous Families With Neurodevelopmental Disorders. JAMA Psychiatry 2017; 74:293-299. [PMID: 28097321 DOI: 10.1001/jamapsychiatry.2016.3798] [Citation(s) in RCA: 163] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Autosomal recessive inherited neurodevelopmental disorders are highly heterogeneous, and many, possibly most, of the disease genes are still unknown. OBJECTIVES To promote the identification of disease genes through confirmation of previously described genes and presentation of novel candidates and provide an overview of the diagnostic yield of exome sequencing in consanguineous families. DESIGN, SETTING, AND PARTICIPANTS Autozygosity mapping in families and exome sequencing of index patients were performed in 152 consanguineous families (the parents descended from a same ancestor) with at least 1 offspring with intellectual disability (ID). The study was conducted from July 1, 2008, to June 30, 2015, and data analysis was conducted from July 1, 2015, to August 31, 2016. RESULTS Of the 152 consanguineous families enrolled, 1 child (in 45 families [29.6%]) or multiple children (107 families [70.4%]) had ID; additional features were present in 140 of the families (92.1%). The mean (SD) age of the children was 10.3 (9.0) years, and 171 of 297 (57.6%) were male. In 109 families (71.7%), potentially protein-disrupting and clinically relevant variants were identified. Of these, a clear clinical genetic diagnosis was made in 56 families (36.8%) owing to 57 (likely) pathogenic variants in 50 genes already established in neurodevelopmental disorders (46 autosomal recessive, 2 X-linked, and 2 de novo) or in 7 previously proposed recessive candidates. In 5 of these families, potentially treatable disorders were diagnosed (mutations in PAH, CBS, MTHFR, CYP27A1, and HIBCH), and in 1 family, 2 disease-causing homozygous variants in different genes were identified. In another 48 families (31.6%), 52 convincing recessive variants in candidate genes that were not previously reported in regard to neurodevelopmental disorders were identified. Of these, 14 were homozygous and truncating in GRM7, STX1A, CCAR2, EEF1D, GALNT2, SLC44A1, LRRIQ3, AMZ2, CLMN, SEC23IP, INIP, NARG2, FAM234B, and TRAP1. The diagnostic yield was higher in individuals with severe ID (35 of 77 [45.5%]), in multiplex families (42 of 107 [39.3%]), in patients with additional features (30 of 70 [42.9%]), and in those with remotely related parents (15 of 34 [44.1%]). CONCLUSIONS AND RELEVANCE Because of the high diagnostic yield of 36.8% and the possibility of identifying treatable diseases or the coexistence of several disease-causing variants, using exome sequencing as a first-line diagnostic approach in consanguineous families with neurodevelopmental disorders is recommended. Furthermore, the literature is enriched with 52 convincing candidate genes that are awaiting confirmation in independent families.
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Hempel M, Casar Tena T, Diehl T, Burczyk MS, Strom TM, Kubisch C, Philipp M, Lessel D. Compound heterozygous GATA5 mutations in a girl with hydrops fetalis, congenital heart defects and genital anomalies. Hum Genet 2017; 136:339-346. [DOI: 10.1007/s00439-017-1762-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/01/2017] [Indexed: 01/21/2023]
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Anikster Y, Haack TB, Vilboux T, Pode-Shakked B, Thöny B, Shen N, Guarani V, Meissner T, Mayatepek E, Trefz FK, Marek-Yagel D, Martinez A, Huttlin EL, Paulo JA, Berutti R, Benoist JF, Imbard A, Dorboz I, Heimer G, Landau Y, Ziv-Strasser L, Malicdan MCV, Gemperle-Britschgi C, Cremer K, Engels H, Meili D, Keller I, Bruggmann R, Strom TM, Meitinger T, Mullikin JC, Schwartz G, Ben-Zeev B, Gahl WA, Harper JW, Blau N, Hoffmann GF, Prokisch H, Opladen T, Schiff M. Biallelic Mutations in DNAJC12 Cause Hyperphenylalaninemia, Dystonia, and Intellectual Disability. Am J Hum Genet 2017; 100:257-266. [PMID: 28132689 PMCID: PMC5294665 DOI: 10.1016/j.ajhg.2017.01.002] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/22/2016] [Indexed: 01/19/2023] Open
Abstract
Phenylketonuria (PKU, phenylalanine hydroxylase deficiency), an inborn error of metabolism, can be detected through newborn screening for hyperphenylalaninemia (HPA). Most individuals with HPA harbor mutations in the gene encoding phenylalanine hydroxylase (PAH), and a small proportion (2%) exhibit tetrahydrobiopterin (BH4) deficiency with additional neurotransmitter (dopamine and serotonin) deficiency. Here we report six individuals from four unrelated families with HPA who exhibited progressive neurodevelopmental delay, dystonia, and a unique profile of neurotransmitter deficiencies without mutations in PAH or BH4 metabolism disorder-related genes. In these six affected individuals, whole-exome sequencing (WES) identified biallelic mutations in DNAJC12, which encodes a heat shock co-chaperone family member that interacts with phenylalanine, tyrosine, and tryptophan hydroxylases catalyzing the BH4-activated conversion of phenylalanine into tyrosine, tyrosine into L-dopa (the precursor of dopamine), and tryptophan into 5-hydroxytryptophan (the precursor of serotonin), respectively. DNAJC12 was undetectable in fibroblasts from the individuals with null mutations. PAH enzyme activity was reduced in the presence of DNAJC12 mutations. Early treatment with BH4 and/or neurotransmitter precursors had dramatic beneficial effects and resulted in the prevention of neurodevelopmental delay in the one individual treated before symptom onset. Thus, DNAJC12 deficiency is a preventable and treatable cause of intellectual disability that should be considered in the early differential diagnosis when screening results are positive for HPA. Sequencing of DNAJC12 may resolve any uncertainty and should be considered in all children with unresolved HPA.
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Vill K, Müller-Felber W, Alhaddad B, Strom TM, Teusch V, Weigand H, Blaschek A, Meitinger T, Haack TB. A homozygous splice variant in AP4S1 mimicking neurodegeneration with brain iron accumulation. Mov Disord 2017; 32:797-799. [PMID: 28150420 DOI: 10.1002/mds.26922] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 12/02/2016] [Accepted: 12/05/2016] [Indexed: 11/11/2022] Open
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Van Damme T, Gardeitchik T, Mohamed M, Guerrero-Castillo S, Freisinger P, Guillemyn B, Kariminejad A, Dalloyaux D, van Kraaij S, Lefeber DJ, Syx D, Steyaert W, De Rycke R, Hoischen A, Kamsteeg EJ, Wong SY, van Scherpenzeel M, Jamali P, Brandt U, Nijtmans L, Korenke GC, Chung BHY, Mak CCY, Hausser I, Kornak U, Fischer-Zirnsak B, Strom TM, Meitinger T, Alanay Y, Utine GE, Leung PKC, Ghaderi-Sohi S, Coucke P, Symoens S, De Paepe A, Thiel C, Haack TB, Malfait F, Morava E, Callewaert B, Wevers RA. Mutations in ATP6V1E1 or ATP6V1A Cause Autosomal-Recessive Cutis Laxa. Am J Hum Genet 2017; 100:216-227. [PMID: 28065471 DOI: 10.1016/j.ajhg.2016.12.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/08/2016] [Indexed: 02/03/2023] Open
Abstract
Defects of the V-type proton (H+) ATPase (V-ATPase) impair acidification and intracellular trafficking of membrane-enclosed compartments, including secretory granules, endosomes, and lysosomes. Whole-exome sequencing in five families affected by mild to severe cutis laxa, dysmorphic facial features, and cardiopulmonary involvement identified biallelic missense mutations in ATP6V1E1 and ATP6V1A, which encode the E1 and A subunits, respectively, of the V1 domain of the heteromultimeric V-ATPase complex. Structural modeling indicated that all substitutions affect critical residues and inter- or intrasubunit interactions. Furthermore, complexome profiling, a method combining blue-native gel electrophoresis and liquid chromatography tandem mass spectrometry, showed that they disturb either the assembly or the stability of the V-ATPase complex. Protein glycosylation was variably affected. Abnormal vesicular trafficking was evidenced by delayed retrograde transport after brefeldin A treatment and abnormal swelling and fragmentation of the Golgi apparatus. In addition to showing reduced and fragmented elastic fibers, the histopathological hallmark of cutis laxa, transmission electron microscopy of the dermis also showed pronounced changes in the structure and organization of the collagen fibers. Our findings expand the clinical and molecular spectrum of metabolic cutis laxa syndromes and further link defective extracellular matrix assembly to faulty protein processing and cellular trafficking caused by genetic defects in the V-ATPase complex.
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Baertling F, Alhaddad B, Seibt A, Budaeus S, Meitinger T, Strom TM, Mayatepek E, Schaper J, Prokisch H, Haack TB, Distelmaier F. Neonatal encephalocardiomyopathy caused by mutations in VARS2. Metab Brain Dis 2017; 32:267-270. [PMID: 27502409 DOI: 10.1007/s11011-016-9890-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/01/2016] [Indexed: 12/22/2022]
Abstract
VARS2 encodes a mitochondrial aminoacyl-tRNA-synthetase. Mutations in VARS2 have recently been identified as a cause of mitochondrial encephalomyopathy in three individuals. However, clinical information remained scarce. Exome sequencing lead us to identify compound heterozygous pathogenic VARS2 variants in a boy presenting with severe lactic acidosis, hypertrophic cardiomyopathy, epilepsy, and abnormalities on brain imaging including hypoplasia of corpus callosum and cerebellum as well as a massive lactate peak on MR-spectroscopy. Studies in patient-derived fibroblasts confirmed the functional relevance of the identified VARS2 variants. Our report expands the phenotypic spectrum associated with this rare mitochondrial defect, in that VARS2 deficiency may also cause severe neonatal presentations with cardiac involvement and structural brain abnormalities.
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Bramswig NC, Caluseriu O, Lüdecke HJ, Bolduc FV, Noel NCL, Wieland T, Surowy HM, Christen HJ, Engels H, Strom TM, Wieczorek D. Heterozygosity for ARID2 loss-of-function mutations in individuals with a Coffin-Siris syndrome-like phenotype. Hum Genet 2017; 136:297-305. [PMID: 28124119 DOI: 10.1007/s00439-017-1757-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/13/2017] [Indexed: 12/15/2022]
Abstract
Chromatin remodeling is a complex process shaping the nucleosome landscape, thereby regulating the accessibility of transcription factors to regulatory regions of target genes and ultimately managing gene expression. The SWI/SNF (switch/sucrose nonfermentable) complex remodels the nucleosome landscape in an ATP-dependent manner and is divided into the two major subclasses Brahma-associated factor (BAF) and Polybromo Brahma-associated factor (PBAF) complex. Somatic mutations in subunits of the SWI/SNF complex have been associated with different cancers, while germline mutations have been associated with autism spectrum disorder and the neurodevelopmental disorders Coffin-Siris (CSS) and Nicolaides-Baraitser syndromes (NCBRS). CSS is characterized by intellectual disability (ID), coarsening of the face and hypoplasia or absence of the fifth finger- and/or toenails. So far, variants in five of the SWI/SNF subunit-encoding genes ARID1B, SMARCA4, SMARCB1, ARID1A, and SMARCE1 as well as variants in the transcription factor-encoding gene SOX11 have been identified in CSS-affected individuals. ARID2 is a member of the PBAF subcomplex, which until recently had not been linked to any neurodevelopmental phenotypes. In 2015, mutations in the ARID2 gene were associated with intellectual disability. In this study, we report on two individuals with private de novo ARID2 frameshift mutations. Both individuals present with a CSS-like phenotype including ID, coarsening of facial features, other recognizable facial dysmorphisms and hypoplasia of the fifth toenails. Hence, this study identifies mutations in the ARID2 gene as a novel and rare cause for a CSS-like phenotype and enlarges the list of CSS-like genes.
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Koch J, Mayr JA, Alhaddad B, Rauscher C, Bierau J, Kovacs-Nagy R, Coene KLM, Bader I, Holzhacker M, Prokisch H, Venselaar H, Wevers RA, Distelmaier F, Polster T, Leiz S, Betzler C, Strom TM, Sperl W, Meitinger T, Wortmann SB, Haack TB. CAD mutations and uridine-responsive epileptic encephalopathy. Brain 2016; 140:279-286. [PMID: 28007989 DOI: 10.1093/brain/aww300] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/14/2016] [Accepted: 10/07/2016] [Indexed: 11/14/2022] Open
Abstract
Unexplained global developmental delay and epilepsy in childhood pose a major socioeconomic burden. Progress in defining the molecular bases does not often translate into effective treatment. Notable exceptions include certain inborn errors of metabolism amenable to dietary intervention. CAD encodes a multifunctional enzyme involved in de novo pyrimidine biosynthesis. Alternatively, pyrimidines can be recycled from uridine. Exome sequencing in three families identified biallelic CAD mutations in four children with global developmental delay, epileptic encephalopathy, and anaemia with anisopoikilocytosis. Two died aged 4 and 5 years after a neurodegenerative disease course. Supplementation of the two surviving children with oral uridine led to immediate cessation of seizures in both. A 4-year-old female, previously in a minimally conscious state, began to communicate and walk with assistance after 9 weeks of treatment. A 3-year-old female likewise showed developmental progress. Blood smears normalized and anaemia resolved. We establish CAD as a gene confidently implicated in this neurometabolic disorder, characterized by co-occurrence of global developmental delay, dyserythropoietic anaemia and seizures. While the natural disease course can be lethal in early childhood, our findings support the efficacy of uridine supplementation, rendering CAD deficiency a treatable neurometabolic disorder and therefore a potential condition for future (genetic) newborn screening.
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Zech M, Boesch S, Maier EM, Borggraefe I, Vill K, Laccone F, Pilshofer V, Ceballos-Baumann A, Alhaddad B, Berutti R, Poewe W, Haack TB, Haslinger B, Strom TM, Winkelmann J. Haploinsufficiency of KMT2B, Encoding the Lysine-Specific Histone Methyltransferase 2B, Results in Early-Onset Generalized Dystonia. Am J Hum Genet 2016; 99:1377-1387. [PMID: 27839873 DOI: 10.1016/j.ajhg.2016.10.010] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 10/25/2016] [Indexed: 12/26/2022] Open
Abstract
Early-onset generalized dystonia represents the severest form of dystonia, a hyperkinetic movement disorder defined by involuntary twisting postures. Although frequently transmitted as a single-gene trait, the molecular basis of dystonia remains largely obscure. By whole-exome sequencing a parent-offspring trio in an Austrian kindred affected by non-familial early-onset generalized dystonia, we identified a dominant de novo frameshift mutation, c.6406delC (p.Leu2136Serfs∗17), in KMT2B, encoding a lysine-specific methyltransferase involved in transcriptional regulation via post-translational modification of histones. Whole-exome-sequencing-based exploration of a further 30 German-Austrian individuals with early-onset generalized dystonia uncovered another three deleterious mutations in KMT2B-one de novo nonsense mutation (c.1633C>T [p.Arg545∗]), one de novo essential splice-site mutation (c.7050-2A>G [p.Phe2321Serfs∗93]), and one inherited nonsense mutation (c.2428C>T [p.Gln810∗]) co-segregating with dystonia in a three-generation kindred. Each of the four mutations was predicted to mediate a loss-of-function effect by introducing a premature termination codon. Suggestive of haploinsufficiency, we found significantly decreased total mRNA levels of KMT2B in mutant fibroblasts. The phenotype of individuals with KMT2B loss-of-function mutations was dominated by childhood lower-limb-onset generalized dystonia, and the family harboring c.2428C>T (p.Gln810∗) showed variable expressivity. In most cases, dystonic symptoms were accompanied by heterogeneous non-motor features. Independent support for pathogenicity of the mutations comes from the observation of high rates of dystonic presentations in KMT2B-involving microdeletion syndromes. Our findings thus establish generalized dystonia as the human phenotype associated with haploinsufficiency of KMT2B. Moreover, we provide evidence for a causative role of disordered histone modification, chromatin states, and transcriptional deregulation in dystonia pathogenesis.
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Kuechler A, Czeschik JC, Graf E, Grasshoff U, Hüffmeier U, Busa T, Beck-Woedl S, Faivre L, Rivière JB, Bader I, Koch J, Reis A, Hehr U, Rittinger O, Sperl W, Haack TB, Wieland T, Engels H, Prokisch H, Strom TM, Lüdecke HJ, Wieczorek D. Bainbridge-Ropers syndrome caused by loss-of-function variants in ASXL3: a recognizable condition. Eur J Hum Genet 2016; 25:183-191. [PMID: 27901041 DOI: 10.1038/ejhg.2016.165] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/29/2016] [Accepted: 10/13/2016] [Indexed: 01/06/2023] Open
Abstract
Truncating ASXL3 mutations were first identified in 2013 by Bainbridge et al. as a cause of syndromic intellectual disability in four children with similar phenotypes using whole-exome sequencing. The clinical features - postulated by Bainbridge et al. to be overlapping with Bohring-Opitz syndrome - were developmental delay, severe feeding difficulties, failure to thrive and neurological abnormalities. This condition was included in OMIM as 'Bainbridge-Ropers syndrome' (BRPS, #615485). To date, a total of nine individuals with BRPS have been published in the literature in four reports (Bainbridge et al., Dinwiddie et al, Srivastava et al. and Hori et al.). In this report, we describe six unrelated patients with newly diagnosed heterozygous de novo loss-of-function variants in ASXL3 and concordant clinical features: severe muscular hypotonia with feeding difficulties in infancy, significant motor delay, profound speech impairment, intellectual disability and a characteristic craniofacial phenotype (long face, arched eyebrows with mild synophrys, downslanting palpebral fissures, prominent columella, small alae nasi, high, narrow palate and relatively little facial expression). The majority of key features characteristic for Bohring-Opitz syndrome were absent in our patients (eg, the typical posture of arms, intrauterine growth retardation, microcephaly, trigonocephaly, typical facial gestalt with nevus flammeus of the forehead and exophthalmos). Therefore we emphasize that BRPS syndrome, caused by ASXL3 loss-of-function variants, is a clinically distinct intellectual disability syndrome with a recognizable phenotype distinguishable from that of Bohring-Opitz syndrome.
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Bramswig NC, Lüdecke HJ, Pettersson M, Albrecht B, Bernier RA, Cremer K, Eichler EE, Falkenstein D, Gerdts J, Jansen S, Kuechler A, Kvarnung M, Lindstrand A, Nilsson D, Nordgren A, Pfundt R, Spruijt L, Surowy HM, de Vries BBA, Wieland T, Engels H, Strom TM, Kleefstra T, Wieczorek D. Identification of new TRIP12 variants and detailed clinical evaluation of individuals with non-syndromic intellectual disability with or without autism. Hum Genet 2016; 136:179-192. [PMID: 27848077 DOI: 10.1007/s00439-016-1743-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 10/28/2016] [Indexed: 01/28/2023]
Abstract
The ubiquitin pathway is an enzymatic cascade including activating E1, conjugating E2, and ligating E3 enzymes, which governs protein degradation and sorting. It is crucial for many physiological processes. Compromised function of members of the ubiquitin pathway leads to a wide range of human diseases, such as cancer, neurodegenerative diseases, and neurodevelopmental disorders. Mutations in the thyroid hormone receptor interactor 12 (TRIP12) gene (OMIM 604506), which encodes an E3 ligase in the ubiquitin pathway, have been associated with autism spectrum disorder (ASD). In addition to autistic features, TRIP12 mutation carriers showed intellectual disability (ID). More recently, TRIP12 was postulated as a novel candidate gene for intellectual disability in a meta-analysis of published ID cohorts. However, detailed clinical information characterizing the phenotype of these individuals was not provided. In this study, we present seven novel individuals with private TRIP12 mutations including two splice site mutations, one nonsense mutation, three missense mutations, and one translocation case with a breakpoint in intron 1 of the TRIP12 gene and clinically review four previously published cases. The TRIP12 mutation-positive individuals presented with mild to moderate ID (10/11) or learning disability [intelligence quotient (IQ) 76 in one individual], ASD (8/11) and some of them with unspecific craniofacial dysmorphism and other anomalies. In this study, we provide detailed clinical information of 11 TRIP12 mutation-positive individuals and thereby expand the clinical spectrum of the TRIP12 gene in non-syndromic intellectual disability with or without ASD.
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Dennert N, Engels H, Cremer K, Becker J, Wohlleber E, Albrecht B, Ehret JK, Lüdecke HJ, Suri M, Carignani G, Renieri A, Kukuk GM, Wieland T, Andrieux J, Strom TM, Wieczorek D, Dieux-Coëslier A, Zink AM. De novo microdeletions and point mutations affecting SOX2 in three individuals with intellectual disability but without major eye malformations. Am J Med Genet A 2016; 173:435-443. [PMID: 27862890 DOI: 10.1002/ajmg.a.38034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 10/10/2016] [Indexed: 01/04/2023]
Abstract
Loss-of-function mutations and deletions of the SOX2 gene are known to cause uni- and bilateral anophthalmia and microphthalmia as well as related disorders such as anophthalmia-esophageal-genital syndrome. Thus, anophthalmia/microphthalmia is the primary indication for targeted, "phenotype first" analyses of SOX2. However, SOX2 mutations are also associated with a wide range of non-ocular abnormalities, such as postnatal growth retardation, structural brain anomalies, hypogenitalism, and developmental delay. The present report describes three patients without anophthalmia/microphthalmia and loss-of-function mutations or microdeletions of SOX2 who had been investigated in a "genotype first" manner due to intellectual disability/developmental delay using whole exome sequencing or chromosomal microarray analyses. This result prompted us to perform SOX2 Sanger sequencing in 192 developmental delay/intellectual disability patients without anophthalmia or microphthalmia. No additional SOX2 loss-of-function mutations were detected in this cohort, showing that SOX2 is clearly not a major cause of intellectual disability without anophthalmia/microphthalmia. In our three patients and four further, reported "genotype first" SOX2 microdeletion patients, anophthalmia/microphthalmia was present in less than half of the patients. Thus, SOX2 is another example of a gene whose clinical spectrum is broadened by the generation of "genotype first" findings using hypothesis-free, genome-wide methods. © 2016 Wiley Periodicals, Inc.
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Kremer LS, Danhauser K, Herebian D, Petkovic Ramadža D, Piekutowska-Abramczuk D, Seibt A, Müller-Felber W, Haack TB, Płoski R, Lohmeier K, Schneider D, Klee D, Rokicki D, Mayatepek E, Strom TM, Meitinger T, Klopstock T, Pronicka E, Mayr JA, Baric I, Distelmaier F, Prokisch H. NAXE Mutations Disrupt the Cellular NAD(P)HX Repair System and Cause a Lethal Neurometabolic Disorder of Early Childhood. Am J Hum Genet 2016; 99:894-902. [PMID: 27616477 DOI: 10.1016/j.ajhg.2016.07.018] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 07/14/2016] [Indexed: 11/29/2022] Open
Abstract
To safeguard the cell from the accumulation of potentially harmful metabolic intermediates, specific repair mechanisms have evolved. APOA1BP, now renamed NAXE, encodes an epimerase essential in the cellular metabolite repair for NADHX and NADPHX. The enzyme catalyzes the epimerization of NAD(P)HX, thereby avoiding the accumulation of toxic metabolites. The clinical importance of the NAD(P)HX repair system has been unknown. Exome sequencing revealed pathogenic biallelic mutations in NAXE in children from four families with (sub-) acute-onset ataxia, cerebellar edema, spinal myelopathy, and skin lesions. Lactate was elevated in cerebrospinal fluid of all affected individuals. Disease onset was during the second year of life and clinical signs as well as episodes of deterioration were triggered by febrile infections. Disease course was rapidly progressive, leading to coma, global brain atrophy, and finally to death in all affected individuals. NAXE levels were undetectable in fibroblasts from affected individuals of two families. In these fibroblasts we measured highly elevated concentrations of the toxic metabolite cyclic-NADHX, confirming a deficiency of the mitochondrial NAD(P)HX repair system. Finally, NAD or nicotinic acid (vitamin B3) supplementation might have therapeutic implications for this fatal disorder.
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Daniil G, Fernandes-Rosa FL, Chemin J, Blesneac I, Beltrand J, Polak M, Jeunemaitre X, Boulkroun S, Amar L, Strom TM, Lory P, Zennaro MC. CACNA1H Mutations Are Associated With Different Forms of Primary Aldosteronism. EBioMedicine 2016; 13:225-236. [PMID: 27729216 PMCID: PMC5264314 DOI: 10.1016/j.ebiom.2016.10.002] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 09/22/2016] [Accepted: 10/03/2016] [Indexed: 01/10/2023] Open
Abstract
Primary aldosteronism (PA) is the most common form of secondary hypertension. Mutations in KCNJ5, ATP1A1, ATP2B3 and CACNA1D are found in aldosterone producing adenoma (APA) and familial hyperaldosteronism (FH). A recurrent mutation in CACNA1H (coding for Cav3.2) was identified in a familial form of early onset PA. Here we performed whole exome sequencing (WES) in patients with different types of PA to identify new susceptibility genes. Four different heterozygous germline CACNA1H variants were identified. A de novo Cav3.2 p.Met1549Ile variant was found in early onset PA and multiplex developmental disorder. Cav3.2 p.Ser196Leu and p.Pro2083Leu were found in two patients with FH, and p.Val1951Glu was identified in one patient with APA. Electrophysiological analysis of mutant Cav3.2 channels revealed significant changes in the Ca2+ current properties for all mutants, suggesting a gain of function phenotype. Transfections of mutant Cav3.2 in H295R-S2 cells led to increased aldosterone production and/or expression of genes coding for steroidogenic enzymes after K+ stimulation. Identification of CACNA1H mutations associated with early onset PA, FH, and APA suggests that CACNA1H might be a susceptibility gene predisposing to PA with different phenotypic presentations, opening new perspectives for genetic diagnosis and management of patients with PA.
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Zech M, Boesch S, Jochim A, Weber S, Meindl T, Schormair B, Wieland T, Lunetta C, Sansone V, Messner M, Mueller J, Ceballos-Baumann A, Strom TM, Colombo R, Poewe W, Haslinger B, Winkelmann J. Clinical exome sequencing in early-onset generalized dystonia and large-scale resequencing follow-up. Mov Disord 2016; 32:549-559. [PMID: 27666935 DOI: 10.1002/mds.26808] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Revised: 08/23/2016] [Accepted: 08/28/2016] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Dystonia is clinically and genetically heterogeneous. Despite being a first-line testing tool for heterogeneous inherited disorders, whole-exome sequencing has not yet been evaluated in dystonia diagnostics. We set up a pilot study to address the yield of whole-exome sequencing for early-onset generalized dystonia, a disease subtype enriched for monogenic causation. METHODS Clinical whole-exome sequencing coupled with bioinformatics analysis and detailed phenotyping of mutation carriers was performed on 16 consecutive cases with genetically undefined early-onset generalized dystonia. Candidate pathogenic variants were validated and tested for cosegregation. The whole-exome approach was complemented by analyzing 2 mutated yet unestablished causative genes in another 590 dystonia cases. RESULTS Whole-exome sequencing detected clinically relevant mutations of known dystonia-related genes in 6 generalized dystonia cases (37.5%), among whom 3 had novel variants. Reflecting locus heterogeneity, identified unique variants were distributed over 5 genes (GCH1, THAP1, TOR1A, ANO3, ADCY5), of which only 1 (ANO3) was mutated recurrently. Three genes (GCH1, THAP1, TOR1A) were associated with isolated generalized dystonia, whereas 2 (ANO3, ADCY5) gave rise to combined dystonia-myoclonus phenotypes. Follow-up screening of ANO3 and ADCY5 revealed a set of distinct variants of interest, the pathogenicity of which was supported by bioinformatics testing and cosegregation work. CONCLUSIONS Our study identified whole-exome sequencing as an effective strategy for molecular diagnosis of early-onset generalized dystonia and offers insights into the heterogeneous genetic architecture of this condition. Furthermore, it provides confirmatory evidence for a dystonia-relevant role of ANO3 and ADCY5, both of which likely associate with a broader spectrum of dystonic expressions than previously thought. © 2016 International Parkinson and Movement Disorder Society.
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Ferreira PG, Oti M, Barann M, Wieland T, Ezquina S, Friedländer MR, Rivas MA, Esteve-Codina A, Rosenstiel P, Strom TM, Lappalainen T, Guigó R, Sammeth M. Sequence variation between 462 human individuals fine-tunes functional sites of RNA processing. Sci Rep 2016; 6:32406. [PMID: 27617755 PMCID: PMC5019111 DOI: 10.1038/srep32406] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/03/2016] [Indexed: 12/23/2022] Open
Abstract
Recent advances in the cost-efficiency of sequencing technologies enabled the combined DNA- and RNA-sequencing of human individuals at the population-scale, making genome-wide investigations of the inter-individual genetic impact on gene expression viable. Employing mRNA-sequencing data from the Geuvadis Project and genome sequencing data from the 1000 Genomes Project we show that the computational analysis of DNA sequences around splice sites and poly-A signals is able to explain several observations in the phenotype data. In contrast to widespread assessments of statistically significant associations between DNA polymorphisms and quantitative traits, we developed a computational tool to pinpoint the molecular mechanisms by which genetic markers drive variation in RNA-processing, cataloguing and classifying alleles that change the affinity of core RNA elements to their recognizing factors. The in silico models we employ further suggest RNA editing can moonlight as a splicing-modulator, albeit less frequently than genomic sequence diversity. Beyond existing annotations, we demonstrate that the ultra-high resolution of RNA-Seq combined from 462 individuals also provides evidence for thousands of bona fide novel elements of RNA processing-alternative splice sites, introns, and cleavage sites-which are often rare and lowly expressed but in other characteristics similar to their annotated counterparts.
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Haack TB, Ignatius E, Calvo-Garrido J, Iuso A, Isohanni P, Maffezzini C, Lönnqvist T, Suomalainen A, Gorza M, Kremer LS, Graf E, Hartig M, Berutti R, Paucar M, Svenningsson P, Stranneheim H, Brandberg G, Wedell A, Kurian MA, Hayflick SA, Venco P, Tiranti V, Strom TM, Dichgans M, Horvath R, Holinski-Feder E, Freyer C, Meitinger T, Prokisch H, Senderek J, Wredenberg A, Carroll CJ, Klopstock T. Absence of the Autophagy Adaptor SQSTM1/p62 Causes Childhood-Onset Neurodegeneration with Ataxia, Dystonia, and Gaze Palsy. Am J Hum Genet 2016; 99:735-743. [PMID: 27545679 PMCID: PMC5010644 DOI: 10.1016/j.ajhg.2016.06.026] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/27/2016] [Indexed: 11/17/2022] Open
Abstract
SQSTM1 (sequestosome 1; also known as p62) encodes a multidomain scaffolding protein involved in various key cellular processes, including the removal of damaged mitochondria by its function as a selective autophagy receptor. Heterozygous variants in SQSTM1 have been associated with Paget disease of the bone and might contribute to neurodegeneration in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Using exome sequencing, we identified three different biallelic loss-of-function variants in SQSTM1 in nine affected individuals from four families with a childhood- or adolescence-onset neurodegenerative disorder characterized by gait abnormalities, ataxia, dysarthria, dystonia, vertical gaze palsy, and cognitive decline. We confirmed absence of the SQSTM1/p62 protein in affected individuals' fibroblasts and found evidence of a defect in the early response to mitochondrial depolarization and autophagosome formation. Our findings expand the SQSTM1-associated phenotypic spectrum and lend further support to the concept of disturbed selective autophagy pathways in neurodegenerative diseases.
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Ronchi CL, Di Dalmazi G, Faillot S, Sbiera S, Assié G, Weigand I, Calebiro D, Schwarzmayr T, Appenzeller S, Rubin B, Waldmann J, Scaroni C, Bartsch DK, Mantero F, Mannelli M, Kastelan D, Chiodini I, Bertherat J, Reincke M, Strom TM, Fassnacht M, Beuschlein F. Genetic Landscape of Sporadic Unilateral Adrenocortical Adenomas Without PRKACA p.Leu206Arg Mutation. J Clin Endocrinol Metab 2016; 101:3526-38. [PMID: 27389594 DOI: 10.1210/jc.2016-1586] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Adrenocortical adenomas (ACAs) are among the most frequent human neoplasias. Genetic alterations affecting the cAMP/protein kinase A signaling pathway are common in cortisol-producing ACAs, whereas activating mutations in the gene encoding β-catenin (CTNNB1) have been reported in a subset of both benign and malignant adrenocortical tumors. However, the molecular pathogenesis of most ACAs is still largely unclear. OBJECTIVE The aim of the study was to define the genetic landscape of sporadic unilateral ACAs. DESIGN AND SETTING Next-generation whole-exome sequencing was performed on fresh-frozen tumor samples and corresponding normal tissue samples. PATIENTS Ninety-nine patients with ACAs (74 cortisol-producing and 25 endocrine inactive) negative for p.Leu206Arg PRKACA mutation. MAIN OUTCOME MEASURES Identification of known and/or new genetic alterations potentially involved in adrenocortical tumorigenesis and autonomous hormone secretion, genotype-phenotype correlation. RESULTS A total of 706 somatic protein-altering mutations were detected in 88 of 99 tumors (median, six per tumor). We identified several mutations in genes of the cAMP/protein kinase A pathway, including three novel mutations in PRKACA, associated with female sex and Cushing's syndrome. We also found genetic alterations in different genes involved in the Wnt/β-catenin pathway, associated with larger tumors and endocrine inactivity, and notably, in many genes of the Ca(2+)-signaling pathway. Finally, by comparison of our genetic data with those available in the literature, we describe a comprehensive genetic landscape of unilateral ACAs. CONCLUSIONS This study provides the largest sequencing effort on ACAs to date. We thereby identified somatic alterations affecting known and novel pathways potentially involved in adrenal tumorigenesis.
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Kenna KP, van Doormaal PTC, Dekker AM, Ticozzi N, Kenna BJ, Diekstra FP, van Rheenen W, van Eijk KR, Jones AR, Keagle P, Shatunov A, Sproviero W, Smith BN, van Es MA, Topp SD, Kenna A, Miller JW, Fallini C, Tiloca C, McLaughlin RL, Vance C, Troakes C, Colombrita C, Mora G, Calvo A, Verde F, Al-Sarraj S, King A, Calini D, de Belleroche J, Baas F, van der Kooi AJ, de Visser M, Ten Asbroek ALMA, Sapp PC, McKenna-Yasek D, Polak M, Asress S, Muñoz-Blanco JL, Strom TM, Meitinger T, Morrison KE, Lauria G, Williams KL, Leigh PN, Nicholson GA, Blair IP, Leblond CS, Dion PA, Rouleau GA, Pall H, Shaw PJ, Turner MR, Talbot K, Taroni F, Boylan KB, Van Blitterswijk M, Rademakers R, Esteban-Pérez J, García-Redondo A, Van Damme P, Robberecht W, Chio A, Gellera C, Drepper C, Sendtner M, Ratti A, Glass JD, Mora JS, Basak NA, Hardiman O, Ludolph AC, Andersen PM, Weishaupt JH, Brown RH, Al-Chalabi A, Silani V, Shaw CE, van den Berg LH, Veldink JH, Landers JE. NEK1 variants confer susceptibility to amyotrophic lateral sclerosis. Nat Genet 2016; 48:1037-42. [PMID: 27455347 PMCID: PMC5560030 DOI: 10.1038/ng.3626] [Citation(s) in RCA: 173] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/24/2016] [Indexed: 12/11/2022]
Abstract
To identify genetic factors contributing to amyotrophic lateral sclerosis (ALS), we conducted whole-exome analyses of 1,022 index familial ALS (FALS) cases and 7,315 controls. In a new screening strategy, we performed gene-burden analyses trained with established ALS genes and identified a significant association between loss-of-function (LOF) NEK1 variants and FALS risk. Independently, autozygosity mapping for an isolated community in the Netherlands identified a NEK1 p.Arg261His variant as a candidate risk factor. Replication analyses of sporadic ALS (SALS) cases and independent control cohorts confirmed significant disease association for both p.Arg261His (10,589 samples analyzed) and NEK1 LOF variants (3,362 samples analyzed). In total, we observed NEK1 risk variants in nearly 3% of ALS cases. NEK1 has been linked to several cellular functions, including cilia formation, DNA-damage response, microtubule stability, neuronal morphology and axonal polarity. Our results provide new and important insights into ALS etiopathogenesis and genetic etiology.
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Colin E, Daniel J, Ziegler A, Wakim J, Scrivo A, Haack TB, Khiati S, Denommé AS, Amati-Bonneau P, Charif M, Procaccio V, Reynier P, Aleck KA, Botto LD, Herper CL, Kaiser CS, Nabbout R, N'Guyen S, Mora-Lorca JA, Assmann B, Christ S, Meitinger T, Strom TM, Prokisch H, Miranda-Vizuete A, Hoffmann GF, Lenaers G, Bomont P, Liebau E, Bonneau D. Biallelic Variants in UBA5 Reveal that Disruption of the UFM1 Cascade Can Result in Early-Onset Encephalopathy. Am J Hum Genet 2016; 99:695-703. [PMID: 27545681 DOI: 10.1016/j.ajhg.2016.06.030] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/28/2016] [Indexed: 01/10/2023] Open
Abstract
Via whole-exome sequencing, we identified rare autosomal-recessive variants in UBA5 in five children from four unrelated families affected with a similar pattern of severe intellectual deficiency, microcephaly, movement disorders, and/or early-onset intractable epilepsy. UBA5 encodes the E1-activating enzyme of ubiquitin-fold modifier 1 (UFM1), a recently identified ubiquitin-like protein. Biochemical studies of mutant UBA5 proteins and studies in fibroblasts from affected individuals revealed that UBA5 mutations impair the process of ufmylation, resulting in an abnormal endoplasmic reticulum structure. In Caenorhabditis elegans, knockout of uba-5 and of human orthologous genes in the UFM1 cascade alter cholinergic, but not glutamatergic, neurotransmission. In addition, uba5 silencing in zebrafish decreased motility while inducing abnormal movements suggestive of seizures. These clinical, biochemical, and experimental findings support our finding of UBA5 mutations as a pathophysiological cause for early-onset encephalopathies due to abnormal protein ufmylation.
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Kurth I, Baumgartner M, Schabhüttl M, Tomni C, Windhager R, Strom TM, Wieland T, Gremel K, Auer-Grumbach M. Whole exome sequencing in congenital pain insensitivity identifies a novel causative intronic NTRK1-mutation due to uniparental disomy. Am J Med Genet B Neuropsychiatr Genet 2016; 171:875-8. [PMID: 27184211 DOI: 10.1002/ajmg.b.32458] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 05/04/2016] [Indexed: 01/01/2023]
Abstract
Congenital insensitivity to pain and anhidrosis (CIPA), also known as hereditary sensory and autonomic neuropathy type IV (HSAN IV), is characterized by recurrent episodes of unexplained high fever, loss of pain perception and temperature sensation, absent sweating, repeated traumatic and thermal injuries, and mild mental retardation. After exclusion of obviously pathogenic mutations in NTRK1, the most common cause of CIPA, whole exome sequencing (WES) was carried out in a CIPA patient with unrelated parents. No mutations in known HSAN genes were identified. However, filtering for genes carrying two rare sequence variations detected 13 homozygous single nucleotide variants (SNV), all being located on chromosome 1. Further analysis strongly suggested that this finding might be best explained by uniparental disomy of chromosome 1. Because NTRK1 is also located on chromosome 1, we re-evaluated WES data and detected a novel intronic sequence variation at position c.2188-12 C>A, homozygously because of uniparental disomy. Subsequent analysis of NTRK1 transcripts in peripheral blood cells of the patient revealed an influence of the variant on mRNA splicing. The C>A transversion generated a novel splice-site, which led to the incorporation of 10 intronic bases into the NTRK1 mRNA and consequently to a non-functional gene product. © 2016 Wiley Periodicals, Inc.
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Calebiro D, Grassi ES, Eszlinger M, Ronchi CL, Godbole A, Bathon K, Guizzardi F, de Filippis T, Krohn K, Jaeschke H, Schwarzmayr T, Bircan R, Gozu HI, Sancak S, Niedziela M, Strom TM, Fassnacht M, Persani L, Paschke R. Recurrent EZH1 mutations are a second hit in autonomous thyroid adenomas. J Clin Invest 2016; 126:3383-8. [PMID: 27500488 DOI: 10.1172/jci84894] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 06/16/2016] [Indexed: 12/22/2022] Open
Abstract
Autonomous thyroid adenomas (ATAs) are a frequent cause of hyperthyroidism. Mutations in the genes encoding the TSH receptor (TSHR) or the Gs protein α subunit (GNAS) are found in approximately 70% of ATAs. The involvement of other genes and the pathogenesis of the remaining cases are presently unknown. Here, we performed whole-exome sequencing in 19 ATAs that were paired with normal DNA samples and identified a recurrent hot-spot mutation (c.1712A>G; p.Gln571Arg) in the enhancer of zeste homolog 1 (EZH1) gene, which codes for a catalytic subunit of the polycomb complex. Targeted screening in an independent cohort confirmed that this mutation occurs with high frequency (27%) in ATAs. EZH1 mutations were strongly associated with known (TSHR, GNAS) or presumed (adenylate cyclase 9 [ADCY9]) alterations in cAMP pathway genes. Furthermore, functional studies revealed that the p.Gln571Arg EZH1 mutation caused increased histone H3 trimethylation and increased proliferation of thyroid cells. In summary, this study revealed that a hot-spot mutation in EZH1 is the second most frequent genetic alteration in ATAs. The association between EZH1 and TSHR mutations suggests a 2-hit model for the pathogenesis of these tumors, whereby constitutive activation of the cAMP pathway and EZH1 mutations cooperate to induce the hyperproliferation of thyroid cells.
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Kopajtich R, Murayama K, Janecke AR, Haack TB, Breuer M, Knisely AS, Harting I, Ohashi T, Okazaki Y, Watanabe D, Tokuzawa Y, Kotzaeridou U, Kölker S, Sauer S, Carl M, Straub S, Entenmann A, Gizewski E, Feichtinger RG, Mayr JA, Lackner K, Strom TM, Meitinger T, Müller T, Ohtake A, Hoffmann GF, Prokisch H, Staufner C. Biallelic IARS Mutations Cause Growth Retardation with Prenatal Onset, Intellectual Disability, Muscular Hypotonia, and Infantile Hepatopathy. Am J Hum Genet 2016; 99:414-22. [PMID: 27426735 DOI: 10.1016/j.ajhg.2016.05.027] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/25/2016] [Indexed: 12/29/2022] Open
Abstract
tRNA synthetase deficiencies are a growing group of genetic diseases associated with tissue-specific, mostly neurological, phenotypes. In cattle, cytosolic isoleucyl-tRNA synthetase (IARS) missense mutations cause hereditary weak calf syndrome. Exome sequencing in three unrelated individuals with severe prenatal-onset growth retardation, intellectual disability, and muscular hypotonia revealed biallelic mutations in IARS. Studies in yeast confirmed the pathogenicity of identified mutations. Two of the individuals had infantile hepatopathy with fibrosis and steatosis, leading in one to liver failure in the course of infections. Zinc deficiency was present in all affected individuals and supplementation with zinc showed a beneficial effect on growth in one.
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