Leukoencephalopathy due to variants in GFPT1-associated congenital myasthenic syndrome

Neurology ◽  
2019 ◽  
Vol 92 (6) ◽  
pp. e587-e593 ◽  
Author(s):  
Guy Helman ◽  
Suvasini Sharma ◽  
Joanna Crawford ◽  
Bijoy Patra ◽  
Puneet Jain ◽  
...  
Keyword(s):  
Genome Sequencing ◽  
Muscle Weakness ◽  
Genetic Diagnosis ◽  
Clinical Information ◽  
Congenital Myasthenic Syndrome ◽  
Cerebral White Matter ◽  
Repetitive Nerve Stimulation ◽  
Hyperintense Signal ◽  
Biological Parents ◽  
Hexosamine Biosynthesis

ObjectiveTo determine the molecular etiology of disease in 4 individuals from 2 unrelated families who presented with proximal muscle weakness and features suggestive of mitochondrial disease.MethodsClinical information and neuroimaging were reviewed. Genome sequencing was performed on affected individuals and biological parents.ResultsAll affected individuals presented with muscle weakness and difficulty walking. In one family, both children had neonatal respiratory distress while the other family had 2 children with episodic deteriorations. In each family, muscle biopsy demonstrated ragged red fibers. MRI was suggestive of a mitochondrial leukoencephalopathy, with extensive deep cerebral white matter T2 hyperintense signal and selective involvement of the middle blade of the corpus callosum. Through genome sequencing, homozygous GFPT1 missense variants were identified in the affected individuals of each family. The variants detected (p.Arg14Leu and p.Thr151Lys) are absent from population databases and predicted to be damaging by in silico prediction tools. Following the genetic diagnosis, nerve conduction studies were performed and demonstrated a decremental response to repetitive nerve stimulation, confirming the diagnosis of myasthenia. Treatment with pyridostigmine was started in one family with favorable response.ConclusionsGFPT1 encodes a widely expressed protein that controls the flux of glucose into the hexosamine-biosynthesis pathway that produces precursors for glycosylation of proteins. GFPT1 variants and defects in other enzymes of this pathway have previously been associated with congenital myasthenia. These findings identify leukoencephalopathy as a previously unrecognized phenotype in GFPT1-related disease and suggest that mitochondrial dysfunction could contribute to this disorder.

scholarly journals A genome sequencing program for novel undiagnosed diseases

2015 ◽  
Vol 17 (12) ◽  
pp. 995-1001 ◽  
Author(s):  
Cinnamon S. Bloss ◽  
Ashley A. Scott-Van Zeeland ◽  
Sarah E. Topol ◽  
Burcu F. Darst ◽  
Debra L. Boeldt ◽  
...  
Keyword(s):  
Genome Sequencing ◽  
Molecular Diagnosis ◽  
Genetic Disorder ◽  
Molecular Genetic ◽  
Genetic Diagnosis ◽  
Clinical Information ◽  
Case Review ◽  
Novel Gene ◽  
A Genome ◽  
Molecular Genetic Diagnosis

Abstract Purpose: The Scripps Idiopathic Diseases of Man (IDIOM) study aims to discover novel gene–disease relationships and provide molecular genetic diagnosis and treatment guidance for individuals with novel diseases using genome sequencing integrated with clinical assessment and multidisciplinary case review. Here we describe the operational protocol and initial results of the IDIOM study. Methods: A total of 121 cases underwent first-tier review by the principal investigators to determine whether the primary inclusion criteria were satisfied, 59 (48.8%) underwent second-tier review by our clinician–scientist review panel, and 17 patients (14.0%) and their family members were enrolled. Results: 60% of cases resulted in a plausible molecular diagnosis, and 18% of cases resulted in a confirmed molecular diagnosis. Two of three confirmed cases led to the identification of novel gene–disease relationships. In the third confirmed case a previously described but unrecognized disease was revealed. In all three confirmed cases a new clinical management strategy was initiated based on the genetic findings. Conclusion: Genome sequencing provides tangible clinical benefit for individuals with idiopathic genetic disease, not only in the context of molecular genetic diagnosis of known rare conditions but also in cases where prior clinical information regarding a new genetic disorder is lacking. Genet Med 17 12, 995–1001.

Combined Muscle Biopsy and Comprehensive Electrophysiology in General Anesthesia is Valuable in Diagnosis of Neuromuscular Disease in Children

2021 ◽  
Author(s):  
Christina E. Hoei-Hansen ◽  
Marie L. B. Tygesen ◽  
Morten Dunø ◽  
John Vissing ◽  
Martin Ballegaard ◽  
...  
Keyword(s):  
Genetic Testing ◽  
Muscle Biopsy ◽  
Neuromuscular Disease ◽  
Genetic Diagnosis ◽  
Congenital Myasthenic Syndrome ◽  
Diagnostic Quality ◽  
Pathogenic Variants ◽  
Combined Use ◽  
Myasthenic Syndrome ◽  
Size Variability

Abstract Aim The diagnostic workup in patients with delayed motor milestones suspected of having either myopathy or a congenital myasthenic syndrome is complex. Our hypothesis was that performance of a muscle biopsy and neurophysiology including stimulated single-fiber electromyography during an anesthetic procedure, combined with genetic testing has a high diagnostic quality. Materials and Methods Clinical and paraclinical data were retrospectively collected from 24 patients aged from 1 month to 10 years (median: 5.2 years). Results Neurophysiology examination was performed in all patients and was abnormal in 11 of 24. No patients had findings suggestive of a myasthenic syndrome. Muscle biopsy was performed in 21 of 24 and was normal in 16. Diagnostic findings included nemaline rods, inclusion bodies, fiber size variability, and type-II fiber atrophy. Genetic testing with either a gene panel or exome sequencing was performed in 18 of 24 patients, with pathogenic variants detected in ACTA1, NEB, SELENON, GRIN2B, SCN8A, and COMP genes. Conclusion Results supporting a neuromuscular abnormality were found in 15 of 24. In six patients (25%), we confirmed a genetic diagnosis and 12 had a clinical neuromuscular diagnosis. The study suggests that combined use of neurophysiology and muscle biopsy in cases where genetic testing does not provide a diagnosis can be useful in children with delayed motor milestones and clinical evidence of a neuromuscular disease.

scholarly journals Clinical and Genetic Features in 31 Serial Chinese Children With Gitelman Syndrome

2021 ◽  
Vol 9 ◽  
Author(s):  
Lingxia Zhang ◽  
Ke Huang ◽  
Shugang Wang ◽  
Haidong Fu ◽  
Jingjing Wang ◽  
...  
Keyword(s):  
Early Diagnosis ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Muscle Weakness ◽  
Growth Retardation ◽  
Gitelman Syndrome ◽  
Compound Heterozygous ◽  
Whole Genome ◽  
Whole Exome ◽  
Laboratory Test Results

Gitelman syndrome (GS, OMIM 263800) is a genetic congenital tubulopathy associated with salt loss, which is characterized by hypokalemic metabolic toxicity, hypocalciuria, and hypomagnesemia. GS, which is typically detected in adolescence or adulthood, has long been considered a benign tubular lesion; however, the disease is associated with a significant decrease in the quality of life. In this study, we assessed the genotype–phenotype correlations based on the medical histories, clinical symptoms, laboratory test results, and whole-exome sequencing profiles from pediatric patients with GS. Between January 2014 and December 2020, all 31 consecutively enrolled patients complained of fatigue, salt craving, and muscle weakness. Sixteen patients demonstrated growth retardation, and five patients presented with nocturia and constipation. All patients presented with hypokalemic metabolic alkalosis, normal blood pressure, hyperaldosteronism, and a preserved glomerular filtration rate, and 24 of the 31 (77.4%) patients had hypomagnesemia. Homozygous, compound heterozygous, and heterozygous mutations in SLC12A3 were detected in 4, 24, and 3 patients, respectively. GS patients often present with muscle weakness and fatigue caused by hypokalemia and hypomagnesemia. Therefore, early diagnosis of GS is important in young children to reduce the possibility of growth retardation, tetany, and seizures. Next-generation sequencing such as whole-exome or whole-genome sequencing provides a practical tool for the early diagnosis and improvement of GS prognosis. Further whole-genome sequencing is expected to reveal more variants in SLC123A among GS patients with single heterozygous mutations.

scholarly journals Rare variants in the genetic background modulate the expressivity of neurodevelopmental disorders

2018 ◽  
Author(s):  
Lucilla Pizzo ◽  
Matthew Jensen ◽  
Andrew Polyak ◽  
Jill A. Rosenfeld ◽  
Katrin Mannik ◽  
...  
Keyword(s):  
Family History ◽  
Genetic Background ◽  
Rare Variants ◽  
De Novo ◽  
Genetic Diagnosis ◽  
Clinical Information ◽  
Disease Genes ◽  
Complete Evaluation ◽  
Rare Cnvs ◽  
Complex Disorders

AbstractPurposeTo assess the contribution of rare variants in the genetic background towards variability of neurodevelopmental phenotypes in individuals with rare copy-number variants (CNVs) and gene-disruptive mutations.MethodsWe analyzed quantitative clinical information, exome-sequencing, and microarray data from 757 probands and 233 parents and siblings who carry disease-associated mutations.ResultsThe number of rare secondary mutations in functionally intolerant genes (second-hits) correlated with the expressivity of neurodevelopmental phenotypes in probands with 16p12.1 deletion (n=23, p=0.004) and in probands with autism carrying gene-disruptive mutations (n=184, p=0.03) compared to their carrier family members. Probands with 16p12.1 deletion and a strong family history presented more severe clinical features (p=0.04) and higher burden of second-hits compared to those with mild/no family history (p=0.001). The number of secondary variants also correlated with the severity of cognitive impairment in probands carrying pathogenic rare CNVs (n=53) or de novo mutations in disease genes (n=290), and negatively correlated with head size among 80 probands with 16p11.2 deletion. These second-hits involved known disease-associated genes such as SETD5, AUTS2, and NRXN1, and were enriched for genes affecting cellular and developmental processes.ConclusionAccurate genetic diagnosis of complex disorders will require complete evaluation of the genetic background even after a candidate gene mutation is identified.

scholarly journals A combined RNA-seq and whole genome sequencing approach for identification of non-coding pathogenic variants in single families

2020 ◽  
Vol 29 (6) ◽  
pp. 967-979 ◽  
Author(s):  
Revital Bronstein ◽  
Elizabeth E Capowski ◽  
Sudeep Mehrotra ◽  
Alex D Jansen ◽  
Daniel Navarro-Gomez ◽  
...  
Keyword(s):  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Genetic Diagnosis ◽  
Genetic Diagnostics ◽  
Whole Genome ◽  
Unique Challenge ◽  
Coding Regions ◽  
Pathogenic Variants ◽  
Number Of Patients ◽  
Coding Variants

Abstract Inherited retinal degenerations (IRDs) are at the focus of current genetic therapeutic advancements. For a genetic treatment such as gene therapy to be successful, an accurate genetic diagnostic is required. Genetic diagnostics relies on the assessment of the probability that a given DNA variant is pathogenic. Non-coding variants present a unique challenge for such assessments as compared to coding variants. For one, non-coding variants are present at much higher number in the genome than coding variants. In addition, our understanding of the rules that govern the non-coding regions of the genome is less complete than our understanding of the coding regions. Methods that allow for both the identification of candidate non-coding pathogenic variants and their functional validation may help overcome these caveats allowing for a greater number of patients to benefit from advancements in genetic therapeutics. We present here an unbiased approach combining whole genome sequencing (WGS) with patient-induced pluripotent stem cell (iPSC)-derived retinal organoids (ROs) transcriptome analysis. With this approach, we identified and functionally validated a novel pathogenic non-coding variant in a small family with a previously unresolved genetic diagnosis.

scholarly journals Congenital myasthenic syndrome due to a TOR1AIP1 mutation: a new disease pathway for impaired synaptic transmission

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Judith Cossins ◽  
Richard Webster ◽  
Susan Maxwell ◽  
Pedro M Rodríguez Cruz ◽  
Ravi Knight ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Synaptic Transmission ◽  
Muscle Weakness ◽  
Nuclear Membrane ◽  
Nerve Stimulation ◽  
Neuromuscular Junctions ◽  
Synaptic Function ◽  
Inherited Disorders ◽  
Repetitive Nerve Stimulation ◽  
Nuclear Membrane Protein

Abstract Congenital myasthenic syndromes are inherited disorders characterized by fatiguable muscle weakness resulting from impaired signal transmission at the neuromuscular junction. Causative mutations have been identified in genes that can affect the synaptic function or structure. We identified a homozygous frameshift deletion c.127delC, p. Pro43fs in TOR1AIP1 in two siblings with limb-girdle weakness and impaired transmission at the neuromuscular synapse. TOR1AIP1 encodes the inner nuclear membrane protein lamin-associated protein 1. On muscle biopsy from the index case, lamin-associated protein 1 was absent from myonuclei. A mouse model with lamin-associated protein 1 conditionally knocked out in striated muscle was used to analyse the role of lamin-associated protein 1 in synaptic dysfunction. Model mice develop fatiguable muscle weakness as demonstrated by using an inverted screen hang test. Electromyography on the mice revealed a decrement on repetitive nerve stimulation. Ex vivo analysis of hemi-diaphragm preparations showed both miniature and evoked end-plate potential half-widths were prolonged which was associated with upregulation of the foetal acetylcholine receptor γ subunit. Neuromuscular junctions on extensor digitorum longus muscles were enlarged and fragmented, and the number of subsynaptic nuclei was significantly increased. Following these findings, electromyography was performed on cases of other nuclear envelopathies caused by mutations in LaminA/C or emerin, but decrement on repetitive nerve stimulation or other indications of defective neuromuscular transmission were not seen. Thus, this report highlights the first nuclear membrane protein in which defective function can lead to impaired synaptic transmission.

scholarly journals Clinical Application of Whole Exome Sequencing to Identify Rare but Remediable Neurologic Disorders

2020 ◽  
Vol 9 (11) ◽  
pp. 3724
Author(s):  
Min-Jee Kim ◽  
Mi-Sun Yum ◽  
Go Hun Seo ◽  
Yena Lee ◽  
Han Na Jang ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Whole Exome Sequencing ◽  
Genetic Diagnosis ◽  
Intractable Epilepsy ◽  
Episodic Ataxia ◽  
Treatment Modalities ◽  
Congenital Myasthenic Syndrome ◽  
Early Application ◽  
Whole Exome ◽  
Neurologic Disorders

Background: The aim of this study was to describe the application of whole exome sequencing (WES) in the accurate genetic diagnosis and personalized treatment of extremely rare neurogenetic disorders. Methods: From 2017 to 2019, children with neurodevelopmental symptoms were evaluated using WES in the pediatric neurology clinic and medical genetics center. The clinical presentation, laboratory findings including the genetic results from WES, and diagnosis-based treatment and outcomes of the four patients are discussed. Results: A total of 376 children with neurodevelopmental symptom were evaluated by WES, and four patients (1.1%) were diagnosed with treatable neurologic disorders. Patient 1 (Pt 1) showed global muscle hypotonia, dysmorphic facial features, and multiple anomalies beginning in the perinatal period. Pt 1 was diagnosed with congenital myasthenic syndrome 22 of PREPL deficiency. Pt 2 presented with hypotonia and developmental arrest and was diagnosed with autosomal recessive dopa-responsive dystonia due to TH deficiency. Pt 3, who suffered from intractable epilepsy and progressive cognitive decline, was diagnosed with epileptic encephalopathy 47 with a heterozygous FGF12 mutation. Pt 4 presented with motor delay and episodic ataxia and was diagnosed with episodic ataxia type II (heterozygous CACNA1A mutation). The patients’ major neurologic symptoms were remarkably relieved with pyridostigmine (Pt 1), levodopa (Pt 2), sodium channel blocker (Pt 3), and acetazolamide (Pt 4), and most patients regained developmental milestones in the follow-up period (0.4 to 3 years). Conclusions: The early application of WES helps in the identification of extremely rare genetic diseases, for which effective treatment modalities exist. Ultimately, WES resulted in optimal clinical outcomes of affected patients.

scholarly journals Clinical and genetic characterization of congenital hyperinsulinism in Spain

2016 ◽  
Vol 174 (6) ◽  
pp. 717-726 ◽  
Author(s):  
R Martínez ◽  
C Fernández-Ramos ◽  
A Vela ◽  
T Velayos ◽  
A Aguayo ◽  
...  
Keyword(s):  
Mutational Analysis ◽  
Genetic Diagnosis ◽  
Clinical Information ◽  
Severe Hypoglycemia ◽  
Compound Heterozygous ◽  
Congenital Hyperinsulinism ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Lower Blood ◽  
Design And Methods

Context Congenital hyperinsulinism (CHI) is a clinically and genetically heterogeneous disease characterized by severe hypoglycemia caused by inappropriate insulin secretion by pancreatic β-cells. Objective To characterize clinically and genetically CHI patients in Spain. Design and methods We included 50 patients with CHI from Spain. Clinical information was provided by the referring clinicians. Mutational analysis was carried out for KCNJ11, ABCC8, and GCK genes. The GLUD1, HNF4A, HNF1A, UCP2, and HADH genes were sequenced depending on the clinical phenotype. Results We identified the genetic etiology in 28 of the 50 CHI patients tested: 21 had a mutation in KATP channel genes (42%), three in GLUD1 (6%), and four in GCK (8%). Most mutations were found in ABCC8 (20/50). Half of these patients (10/20) were homozygous or compound heterozygous, with nine being unresponsive to diazoxide treatment. The other half had heterozygous mutations in ABCC8, six of them being unresponsive to diazoxide treatment and four being responsive to diazoxide treatment. We identified 22 different mutations in the KATP channel genes, of which ten were novel. Notably, patients with ABCC8 mutations were diagnosed earlier, with lower blood glucose levels and required higher doses of diazoxide than those without a genetic diagnosis. Conclusions Genetic analysis revealed mutations in 56% of the CHI patients. ABCC8 mutations are the most frequent cause of CHI in Spain. We found ten novel mutations in the KATP channel genes. The genetic diagnosis is more likely to be achieved in patients with onset within the first week of life and in those who fail to respond to diazoxide treatment.

scholarly journals The NSIGHT1 Randomized Controlled Trial: Rapid Whole Genome Sequencing for Accelerated Etiologic Diagnosis in Critically Ill Infants

2017 ◽  
Author(s):  
Josh E. Petrikin ◽  
Julie A. Cakici ◽  
Michelle M. Clark ◽  
Laurel K. Willig ◽  
Nathaly M. Sweeney ◽  
...  
Keyword(s):  
Intensive Care ◽  
Whole Genome Sequencing ◽  
Intensive Care Units ◽  
Genome Sequencing ◽  
Genetic Diagnosis ◽  
Pediatric Intensive Care ◽  
Genomic Sequencing ◽  
Whole Genome ◽  
Randomized Controlled ◽  
Standard Tests

AbstractImportanceGenetic disorders, including congenital anomalies, are a leading cause of morbidity and mortality in infants, especially in neonatal and pediatric intensive care units (NICU and PICU). While genomic sequencing is useful for diagnosis of genetic diseases, results are usually reported too late to guide inpatient management.ObjectiveTo test the hypothesis that rapid whole genome sequencing (rWGS) increases the proportion of infants in NICUs and PICUs receiving a genetic diagnosis within 28 days.DesignAn investigator-initiated, partially blinded, pragmatic, randomized controlled study with enrollment from October 2014 - June 2016, and follow up until December 2016.SettingA regional neonatal and pediatric intensive care unit in a tertiary referral childrens hospital.ParticipantsSixty five of 129 screened families with infants aged less than four months, in neonatal and pediatric intensive care units, and with illnesses of unknown etiology, completed the study.InterventionParent and infant trio rWGS.Main Outcome and MeasureThe hypothesis and end-points were formulated a priori. The primary end-point was rate of genetic diagnosis within 28 days of enrollment or first standard test order.ResultsTwenty six female proband infants, 37 male infants, and two infants of undetermined sex were randomized to receive rWGS plus standard tests (n=32, cases) or standard tests alone (n=33, controls). The study was terminated early due to loss of equipoise: 63% (21) controls received genomic sequencing as standard tests. Nevertheless, intention to treat analysis showed the rate of genetic diagnosis within 28 days to be higher in cases (31%, ten of 32) than controls (3%, one of 33; difference, 28% [95% CI, 10% to 46%]; p=0.003). Among infants enrolled in the first 25 days of life, the rate of neonatal diagnosis was higher in cases (32%, seven of 22) than controls (0%, zero of 23; difference, 32% [95% CI, 11% to 53%]; p=0.004). Age at diagnosis (median in cases 25 days, range 14-90 days vs median in controls 130 days, range 37-451) and time to diagnosis (median in cases thirteen days, range 1-84 days vs median in controls 107 days, range 21-429 days) were significantly less in cases than controls (p=0.04).CONCLUSIONSrWGS increased the proportion of infants in a regional NICU and PICU who received a timely diagnosis of a genetic disease. Additional, adequately powered studies are needed to determine whether accelerated diagnosis is associated with improved outcomes in this setting. ClinicalTrials.gov Identifier: NCT02225522.

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