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1.
J Neuromuscul Dis ; 6(4): 503-515, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31594245

RESUMO

OBJECTIVE: Spinal muscular atrophy (SMA) is the most common neurodegenerative disease in childhood. The study was conducted to assess the impact of early detection of SMA by newborn screening (NBS) on the clinical course of the disease. METHODS: Screening was performed in two federal states of Germany, Bavaria and North Rhine Westphalia, between January 2018 and February 2019. The incidence in the screening population was calculated as number of detected patients with a homozygous deletion in the SMN1-gene per number of screened patients. To get an idea about the incidence of newly diagnosed SMA in the year prior to screening a survey covering all neuropediatric centers in the state of Bavaria was conducted, identifying all SMA-cases in 2017 and 2018. Following positive NBS and confirmatory diagnostic test, treatment was advised according to the recommendations of the "American SMA NBS Multidisciplinary Working Group". Immediate treatment with Nusinersen was recommended in children with 2 and 3 SMN2 copies and a conservative strict follow-up strategy in children with ≥4 copies. All children underwent regular standardized neuropediatric examination, CHOP INTEND and HINE-2 testing as well as electrophysiological exams every 2-3 months. RESULTS: 165,525 children were screened. 22 cases of SMA were identified, meaning an incidence rate of 1:7524. SMN2 copy number analysis showed 2 SMN2 copies in 45% of patients, 3 SMN2 copies in 19 % and 4 SMN2 copies in 36%. These findings are confirmed in the most recent statistical data-cut from 31st August 2019 (incidence 1:7089, 2 SMN2 copies in 44%, 3 in 15% and 4 in 38%). Comparison with up-to-date German data on SMA incidence and the Bavarian survey give evidence that NBS did not lead to a relevant increase in incidence. 10 patients with 2 or 3 SMN2 copies were treated with Nusinersen, starting between 15- 39 days after birth, in 7/10 patients before onset of symptoms. Presymptomatically treated patients (age at last examination: 1- 12 months, median 8 months) showed no muscle weakness by the age of one month to one year. One child with 4 SMN2 copies became symptomatic at the age of 8 months. CONCLUSIONS: Newborn screening, resulting in presymptomatic treatment, improves outcome in children with genetically proven SMA. Newborn screening for SMA should be introduced in all countries where therapy is available. An immediate therapy in cases with 4 SMN2 copies should be considered.

2.
Nat Commun ; 10(1): 4790, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31636353

RESUMO

Alterations of Ca2+ homeostasis have been implicated in a wide range of neurodegenerative diseases. Ca2+ efflux from the endoplasmic reticulum into the cytoplasm is controlled by binding of inositol 1,4,5-trisphosphate to its receptor. Activated inositol 1,4,5-trisphosphate receptors are then rapidly degraded by the endoplasmic reticulum-associated degradation pathway. Mutations in genes encoding the neuronal isoform of the inositol 1,4,5-trisphosphate receptor (ITPR1) and genes involved in inositol 1,4,5-trisphosphate receptor degradation (ERLIN1, ERLIN2) are known to cause hereditary spastic paraplegia (HSP) and cerebellar ataxia. We provide evidence that mutations in the ubiquitin E3 ligase gene RNF170, which targets inositol 1,4,5-trisphosphate receptors for degradation, are the likely cause of autosomal recessive HSP in four unrelated families and functionally evaluate the consequences of mutations in patient fibroblasts, mutant SH-SY5Y cells and by gene knockdown in zebrafish. Our findings highlight inositol 1,4,5-trisphosphate signaling as a candidate key pathway for hereditary spastic paraplegias and cerebellar ataxias and thus prioritize this pathway for therapeutic interventions.

3.
Clin EEG Neurosci ; : 1550059419876518, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31554424

RESUMO

Background. Next-generation sequencing (NGS) describes new powerful techniques of nucleic acid analysis, which allow not only disease gene identification diagnostics but also applications for transcriptome/methylation analysis and meta-genomics. NGS helps identify many monogenic epilepsy syndromes. Pediatric epilepsy patients can be tested using NGS epilepsy panels to diagnose them, thereby influencing treatment choices. The primary objective of this study was to evaluate the impact of genetic testing on clinical decision making in pediatric epilepsy patients. Methods. We completed a single-center retrospective cohort study of 91 patients (43 male) aged 19 years or less undergoing NGS with epilepsy panels differing in size ranging from 5 to 434 genes from October 2013 to September 2017. Results. During a mean time of 3.6 years between symptom onset and genetic testing, subjects most frequently showed epileptic encephalopathy (40%), focal epilepsy (33%), and generalized epilepsy (18%). In 16 patients (18% of the study population), "pathogenic" or "likely pathogenic" results according to ACMG criteria were found. Ten of the 16 patients (63%) experienced changes in clinical management regarding their medication and avoidance of further diagnostic evaluation, that is, presurgical evaluation. Conclusion. NGS epilepsy panels contribute to the diagnosis of pediatric epilepsy patients and may change their clinical management with regard to both preventing unnecessary and potentially harmful diagnostic procedures and management. Thus, the present data support the early implementation in order to adopt clinical management in selected cases and prevent further invasive investigations. Given the relatively small sample size and heterogeneous panels a larger prospective study with more homogeneous panels would be helpful to further determine the impact of NGS on clinical decision making.

4.
Eur J Hum Genet ; 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31363188

RESUMO

Establishing nucleic acid-based assays for genetic newborn screening (NBS) provides the possibility to screen for genetically encoded diseases like spinal muscular atrophy (SMA), best before the onset of symptoms. Such assays should be easily scalable to 384-well reactions that make the screening of up to 2000 samples per day possible. We developed a test procedure based on a cleanup protocol for dried blood spots and a quantitative (q)PCR to screen for a homozygous deletion of exon 7 of the survival of motor neuron 1 gene (SMN1) that is responsible for >95% of SMA patients. Performance of this setup is evaluated in detail and tested on routine samples. Our cleanup method for nucleic acids from dried blood spots yields enough DNA for diverse subsequent qPCR applications. To date, we have applied this approach to test 213,279 samples within 18 months. Thirty patients were identified and confirmed, implying an incidence of 1:7109 for the homozygous deletion. Using our cleanup method, a rapid workflow could be established to prepare nucleic acids from dried blood spot cards. Targeting the exon 7 deletion, no invalid, false-positive, or false-negative results were reported to date. This allows timely identification of the disease and grants access to the recently introduced treatment options, in most cases before the onset of symptoms. Carriers are not identified, thus, there are no concerns of whether to report them.

5.
J Neurol ; 266(12): 2929-2941, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31444560

RESUMO

OBJECTIVE: Childhood arterial ischaemic stroke (AIS) is rare, but causes significant morbidity and mortality. We aimed to investigate incidence, age-dependent clinical presentation, and risk factors and to discuss the medical care situation in Germany. METHODS: This prospective epidemiological study was conducted via ESPED (Erhebungseinheit für Seltene Pädiatrische Erkrankungen in Deutschland), a hospital-based German nation-wide surveillance unit for rare pediatric diseases. Children aged 28 days-18 years with first AIS between January 2015 and December 2017 were included. RESULTS: In the 3-year period, 164 children were reported. Incidence showed peaks in infants, children < 2 years of age, and adolescents (12-18 years), with a significant male predominance observed in adolescents only. Independent of age, most children (91%) presented with focal symptoms, particularly with acute hemiparesis. The occurrence of seizures in infants (57%) and more nonspecific symptoms in school-children and adolescents (54%) is considered noteworthy. Prothrombotic states (34%), cardiac disorders (29%), and arteriopathies (19%) were the most frequently identified risk factors. The majority of children (72/131, thus 55%) were discharged home after acute care phase. At time of discharge, most common neurological symptoms were hemiparesis (42%), facial palsy (15%), and speech disturbance (12%). CONCLUSION: This study provides population-based data of childhood AIS which may be useful for further research. The improvement of acute stroke management is needed for children, but also the standardization of post-stroke care in the outpatient setting has to be structured. Considering the higher stroke incidence in (male) adolescents, it is advisable to combine research activities in adolescents and young adults.

7.
Hum Genet ; 137(11-12): 911-919, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30460542

RESUMO

Mutations in the SACS gene have been initially reported in a rare autosomal recessive cerebellar ataxia syndrome featuring prominent cerebellar atrophy, spasticity and peripheral neuropathy as well as retinal abnormalities in some cases (autosomal recessive spastic ataxia of Charlevoix-Saguenay, ARSACS). In the past few years, the phenotypic spectrum has broadened, mainly owing to the availability and application of high-throughput genetic testing methods. We identified nine patients (three sib pairs, three singleton cases) with isolated, non-syndromic hereditary motor and sensory neuropathy (HMSN) who carried pathogenic SACS mutations, either in the homozygous or compound heterozygous state. None of the patients displayed spasticity or pyramidal signs. Ataxia, which was noted in only three patients, was consistent with a sensory ataxia. Nerve conduction and nerve biopsy studies showed mixed demyelinating and axonal neuropathy. Brain MRI scans were either normal or revealed isolated upper vermis atrophy of the cerebellum. Our findings confirm the broad clinical spectrum associated with SACS mutations, including pure polyneuropathy without characteristic clinical and brain imaging manifestations of ARSACS.

8.
Klin Padiatr ; 230(6): 319-325, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30304740

RESUMO

HINTERGRUND: Die zeitliche Verzögerung zwischen Symptombeginn und Diagnose ist eine Herausforderung in der Behandlung von Kindern mit arteriell ischämischem Schlaganfall. Frühere Studien zur klinischen Präsentation beschäftigten sich v. a. mit kumulativen Symptomen. ZIELSETZUNG: Ziel dieser Studie ist es, mögliche Symptommuster aufzuzeigen. METHODEN: In einer aktiven Beobachtungsstudie zwischen 01/2015 und 12/2016 (ESPED-Studie) wurden Kinder mit Erstdiagnose eines arteriell ischämischen Schlaganfalls eingeschlossen. Isoliert auftretende Erstsymptome wurden verschiedenen Symptomkombinationen gegenübergestellt. Zudem wurde untersucht, inwieweit ein als "akut" oder "progredient" klassifiziertes Auftreten der Symptome Rückschlüsse auf die zugrundeliegende Ätiologie erlaubt. ERGEBNISSE: Es wurden 99 Kinder in die Studie eingeschlossen. Unabhängig vom Alter traten überwiegend fokale Symptome auf (86%). Krampfanfälle als Initialsymptom wurden insbesondere bei Säuglingen beschrieben (67%), wohin-gegen diffuse, unspezifische Symptome vor allem bei Vorschulkindern (38%) und älteren Kindern (59%) auftraten. Isoliert traten fokale Symptome bei 37 Kindern auf, 48 Kinder zeigten zusätzlich unspezifische Symptome, darunter auch 9 Kinder mit Krampfanfällen. Isolierte unspezifische Symptome zeigten sich lediglich bei 7 Kindern, 2 Kinder wurden nur mit Krampfanfällen symptomatisch. Die Akuität des Symptombeginns wurde bei 53/78 als "akut" und bei "25/78 Fällen als "progredient" klassifiziert, lieferte jedoch keinen Hinweis auf die zugrundeliegende Ätiologie. SCHLUSSFOLGERUNG: Jedes neue fokal neurologische Defizit sollte unabhängig vom Auftreten (isoliert oder kombiniert, akut oder progredient) an einen kindlichen Schlaganfall denken lassen. BACKGROUND: Time delay between onset of clinical symptoms and diagnosis is a challenge in childhood arterial ischemic stroke. Most previous studies reported cumulative symptoms. OBJECTIVE: We attempted to identify typical symptom patterns and assessed their emergence in childhood stroke. METHODS: Prospective active surveillance in ESPED, a hospital based Pediatric Surveillance Unit for rare diseases in Germany, between January 2015 and December 2016. Case definition: first diagnosis of a radiologically confirmed arterial ischemic stroke. Symptom patterns were identified as occurring in isolation or in combination. We distinguished acute vs. progressive onset. We ascertained risk factors to identify the possible etiology. RESULTS: 99 children with childhood arterial ischemic stroke were reported. Focal symptoms were the predominant presenting feature (86%), independent of age. Seizures were more often seen in infants < 1 year (67%), whereas diffuse symptoms were more present in pre-school children (38%) and older children (59%). 37 children had focal features alone and 48 additional non-specific features, including 9 with seizures. Isolated non-specific features accounted for 7 cases, and 2 children had (focal) seizures as the only symptom. In 77% of all cases at least one risk factor was identified. The emergence of symptoms was acute in 53/78 cases and progressive in 25/78 cases. The pattern of emergence was unrelated to the underlying etiology. CONCLUSIONS: Any new focal neurological deficit in isolation, or associated with seizures or further non-specific symptoms should alert to childhood stroke.

9.
Acta Neurol Scand ; 138(6): 475-481, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30259965

RESUMO

OBJECTIVES: Neuropsychological sequelae are a feature of benign epilepsy with centrotemporal spikes (BECTS) in children. A correlation between the frequency of interictal EEG discharges and the cognitive as well as behavioral profile of the patients has been suspected but not proven. MATERIALS AND METHODS: Children with BECTS that had not yet been treated were included into a randomized controlled trial. In the initial visit, EEGs were recorded. The frequency of interictal discharges was quantified. Correlations between the discharge frequency and the performance in a neuropsychological test battery were examined. RESULTS: The cognitive test results were within or slightly above normal range (Culture-free intelligence test: 99.4%-confidence interval [CI]: [50.3, 59.9], test standardized to a population mean of 50). Parent-reported behavioral abnormalities were statistically significantly increased (CBCL total score CI: [51.9, 61.9], population mean as above). Correlations between the frequency of interictal epileptic discharges and the test results could not be identified (lowest encountered P-value: 0.034, not significant after correction for multiple testing). CONCLUSION: The data do not support the hypothesis that the frequency of the interictal EEG discharges influences the neurocognitive performance or behavioral parameters of children with BECTS.

10.
Front Pediatr ; 6: 182, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29988546

RESUMO

Objective: Acute childhood stroke is an emergency requiring a high level of awareness among first-line healthcare providers. This survey serves as an indicator of the awareness of, the interest in, and knowledge of childhood stroke of German pediatricians. Methods: Thousand six hundred and ninety-seven physicians of pediatric in- and outpatient facilities in Bavaria, Germany, were invited via email to an online-survey about childhood stroke. Results: The overall participation rate was 14%. Forty-six percent of participants considered a diagnosis of childhood stroke at least once during the past year, and 47% provide care for patients who have suffered childhood stroke. The acronym FAST (Face-Arm-Speech-Time-Test) was correctly cited in 27% of the questionnaires. Most commonly quoted symptoms of childhood stroke were hemiparesis (90%), speech disorder (58%), seizure (44%), headache (40%), and impaired consciousness (33%). Migraine (63%), seizure (39%), and infections of the brain (31%) were most frequently named as stroke mimics. Main diagnostic measures indicated were magnetic resonance imaging (MRI) (96%) and computer tomography (CT) (55%). Main therapeutic strategies were thrombolysis (80%), anticoagulation (41%), neuroprotective measures, and thrombectomies (15% each). Thirty-nine percent of participants had taken part in training sessions, 61% studied literature, 37% discussed with colleagues, and 25% performed internet research on childhood stroke. Ninety-three percent of participants approve skill enhancement, favoring training sessions (80%), publications (43%), and web based offers (35%). Consent for offering a flyer on the topic to caregivers in facilities was given in 49%. Conclusion: Childhood stroke constitutes a topic of clinical importance to pediatricians. Participants demonstrate a considerable level of comprehension concerning the subject, but room for improvement remains. A multi-modal approach encompassing an elaborate training program, regular educational publications in professional journals, and web based offers could reach a broad range of health care providers. Paired with a public adult and childhood stroke awareness campaign, these efforts could contribute to optimize the care for children suffering from stroke.

11.
Neuropediatrics ; 49(5): 330-338, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29940663

RESUMO

BACKGROUND: Primary microcephaly and profound global developmental delay have been considered the core clinical phenotype in patients with bi-allelic PRUNE1 mutations. METHODS: Linkage analysis and whole-exome sequencing (WES) in a multiplex family and extraction of further cases from a WES repository containing 571 children with severe developmental disabilities and neurologic symptoms. RESULTS: We identified bi-allelic PRUNE1 mutations in twelve children from six unrelated families. All patients who survived beyond the first 6 months of life had early-onset global developmental delay, bilateral spastic paresis, dysphagia and difficult-to-treat seizures, while congenital or later-evolving microcephaly was not a consistent finding. Brain MRI showed variable anomalies with progressive cerebral and cerebellar atrophies and T2-hyperintense brain stem lesions. Peripheral neuropathy was documented in five cases. Disease course was progressive in all patients and eight children died in the first or early second decade of life. In addition to the previously reported missense mutation p.(Asp106Asn), we observed a novel homozygous missense variant p.(Leu172Pro) and a homozygous contiguous gene deletion encompassing most of the PRUNE1 gene and part of the neighboring BNIPL gene. CONCLUSIONS: PRUNE1 deficiency causes severe early-onset disease affecting the central and peripheral nervous systems. Microcephaly is probably not a universal feature.

12.
Eur J Paediatr Neurol ; 22(3): 507-515, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29551660

RESUMO

OBJECTIVE: The objective of our study was to evaluate the knowledge about fetal alcohol spectrum disorders (FASD) and the implementation of the German guideline for FASD among different professionals in the health and social system and among parents with children with FASD. METHODS: A questionnaire about FASD, containing 20 items, was sent by post to all children's hospitals (n = 287), all hospitals for child and adolescent psychiatry (n = 173), all social paediatric centres (n = 162), all neuropaediatricians (n = 129) and all youth welfare offices (n = 672) in Germany. Furthermore a link to the questionnaire as online version was put in the member's newsletter by 14 relevant professional societies. Besides, the questionnaire was distributed personally to the attendees of the annual national FASD conference (n = 363). RESULTS: Altogether 428 persons took part in the survey. 273 participants were professionals and 155 parents of children with FASD. More than 95% of the professionals and parents knew that alcohol consumption during pregnancy constitutes a risk for the child. The prevalence of maternal alcohol consumption and of FASD was underestimated. Although approx. 70% of the professionals knew which disorders belong to FASD just a few could tell their specific deficits. Questions regarding effective intervention for children with FASD and the long-term outcome were only partially answered correctly. DISCUSSION: Professionals in the German health and social system are aware of FASD but underestimate the level of damage and the impact on every day functioning of the affected people.


Assuntos
Transtornos do Espectro Alcoólico Fetal , Fidelidade a Diretrizes/estatística & dados numéricos , Conhecimentos, Atitudes e Prática em Saúde , Pessoal de Saúde , Pais , Adolescente , Criança , Feminino , Transtornos do Espectro Alcoólico Fetal/epidemiologia , Alemanha , Humanos , Masculino , Gravidez , Prevalência , Inquéritos e Questionários
13.
Seizure ; 56: 115-120, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29475094

RESUMO

PURPOSE: BECTS (benign childhood epilepsy with centrotemporal spikes) is associated with characteristic EEG findings. This study examines the influence of anti-convulsive treatment on the EEG. METHODS: In a randomized controlled trial including 43 children with BECTS, EEGs were performed prior to treatment with either Sulthiame or Levetiracetam as well as three times under treatment. Using the spike-wave-index, the degree of EEG pathology was quantified. The EEG before and after initiation of treatment was analyzed. Both treatment arms were compared and the EEG of the children that were to develop recurrent seizures was compared with those that were successfully treated. RESULTS: Regardless of the treatment agent, the spike-wave-index was reduced significantly under treatment. There were no differences between the two treatment groups. In an additional analysis, the EEG characteristics of the children with recurrent seizures differed statistically significant from those that did not have any further seizures. CONCLUSION: Both Sulthiame and Levetiracetam influence the EEG of children with BECTS. Persistent EEG pathologies are associated with treatment failures.


Assuntos
Anticonvulsivantes/uso terapêutico , Ondas Encefálicas/efeitos dos fármacos , Epilepsia Rolândica/tratamento farmacológico , Piracetam/análogos & derivados , Tiazinas/uso terapêutico , Criança , Método Duplo-Cego , Eletroencefalografia , Feminino , Alemanha , Humanos , Levetiracetam , Masculino , Piracetam/uso terapêutico , Estudos Retrospectivos , Estatísticas não Paramétricas , Resultado do Tratamento
14.
Eur J Paediatr Neurol ; 22(3): 380-386, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29370976

RESUMO

OBJECTIVE: Acute treatment of childhood arterial ischaemic stroke and prevention strategies for recurrent stroke episodes depend strongly on each child's individual risk profile. The aim of this study is to characterize risk factors for childhood stroke, their occurrence in isolation or combination, and to identify possible common risk factor patterns. METHODS: This population-based study was conducted via ESPED, a surveillance unit for rare paediatric diseases in Germany. Children aged >28days and <18 years with an acute arterial ischaemic stroke occurring between January 2015 and December 2016 were included. RESULTS: Among 99 reported children with arterial ischaemic stroke, 56 children were male. Male predominance was significant in adolescents from 12 years old onward. Arterial ischaemic stroke was more common in very young children <2 years of age and in adolescence. No risk factor was identified in 27 children. Hypercoagulable states (29%), cardiac disorders (24%), and arteriopathies (21%) were the most common risk factors. Some risk factor categories were more likely to be identified in isolation (i.e. cardiac disorders, prothrombotic abnormalities and chronic head and neck disorders) than others. The number of risk factors (n = 0-4) per patient and risk factor categories did not differ by age. CONCLUSION: Although we could not identify common patterns of risk factor combinations, several risk factors occurred more likely in isolation than others. Further research should focus on the impact of isolated presumed childhood stroke risk factors like certain prothrombotic abnormalities, migraine or a patent foramen ovale. With regard to different age groups, stroke mechanisms in male adolescents require particular attention.


Assuntos
Acidente Vascular Cerebral/etiologia , Adolescente , Criança , Pré-Escolar , Feminino , Alemanha , Humanos , Lactente , Recém-Nascido , Masculino , Fatores de Risco , Acidente Vascular Cerebral/epidemiologia
15.
Eur J Paediatr Neurol ; 22(1): 72-81, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28927886

RESUMO

To investigate frequency and phenotype of TNFRSF1A and MEFV mutations in childhood-onset multiple sclerosis (MS). Twenty-nine clinically well characterized patients were investigated for mutations in exons 2, 3, 4, and 6 of the TNFRSF1A gene and in exons 2, 3, 9, 10 of the MEFV gene. Standardized morbidity ratio (SMR) was used to assess whether the number of observed mutations was higher than expected. Eleven out of 29 patients tested positive for mutations. Heterozygosity for the TNFRSF1A R92Q (rs4149584) variant was found in 6/11 mutation-positive patients. The SMR for R92Q in our pediatric MS population was 4.6 (95% CI 1.7-10.0), 7.0 (95% CI 2.6-15.2), and 13.6 (95% CI 5.0-29.7), depending on reference population. Six patients carried at least one heterozygous MEFV mutation with SMRs of 21.4 (95% CI 7.9-46.6) and 14.6 (95% CI 5.4-31.9). Clinical characteristics of childhood MS patients with or without mutations did not differ significantly. Conclusion One third of our childhood MS patients had a heterozygous mutation in the TNFRSF1A and/or MEFV gene. This proportion by far exceeds the number of mutations expected and was higher than in adult MS patients, suggesting that these mutations might contribute to the pathogenesis of childhood MS.


Assuntos
Esclerose Múltipla/genética , Pirina/genética , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Adolescente , Idade de Início , Criança , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Masculino , Mutação
20.
Am J Hum Genet ; 99(6): 1377-1387, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27839873

RESUMO

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.


Assuntos
Distúrbios Distônicos/genética , Haploinsuficiência/genética , Histona-Lisina N-Metiltransferase/genética , Lisina/metabolismo , Adolescente , Adulto , Idade de Início , Sequência de Bases , Criança , Feminino , Humanos , Masculino , Linhagem , Adulto Jovem
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