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1.
Am J Med Genet A ; 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31633297

RESUMO

Hennekam lymphangiectasia-lymphedema syndrome is an autosomal recessive disorder characterized by congenital lymphedema, intestinal lymphangiectasia, facial dysmorphism, and variable intellectual disability. Known disease genes include CCBE1, FAT4, and ADAMTS3. In a patient with clinically diagnosed Hennekam syndrome but without mutations or copy-number changes in the three known disease genes, we identified a homozygous single-exon deletion affecting FBXL7. Specifically, exon 3, which encodes the F-box domain and several leucine-rich repeats of FBXL7, is eliminated. Our analyses of databases representing >100,000 control individuals failed to identify biallelic loss-of-function variants in FBXL7. Published studies in Drosophila indicate Fbxl7 interacts with Fat, of which human FAT4 is an ortholog, and mutation of either gene yields similar morphological consequences. These data suggest that FBXL7 may be the fourth gene for Hennekam syndrome, acting via a shared pathway with FAT4.

3.
Ann Neurol ; 85(6): 921-926, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30937933

RESUMO

SLC1A2 is a trimeric transporter essential for clearing glutamate from neuronal synapses. Recurrent de novo SLC1A2 missense variants cause a severe, early onset developmental and epileptic encephalopathy via an unclear mechanism. We demonstrate that all 3 variants implicated in this condition localize to the trimerization domain of SLC1A2, and that the Leu85Pro variant acts via a dominant negative mechanism to reduce, but not eliminate, wild-type SLC1A2 protein localization and function. Finally, we demonstrate that treatment of a 20-month-old SLC1A2-related epilepsy patient with the SLC1A2-modulating agent ceftriaxone did not result in a significant change in daily spasm count. ANN NEUROL 2019;85:921-926.

6.
Nat Commun ; 9(1): 4619, 2018 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-30397230

RESUMO

Chromatin remodeling is of crucial importance during brain development. Pathogenic alterations of several chromatin remodeling ATPases have been implicated in neurodevelopmental disorders. We describe an index case with a de novo missense mutation in CHD3, identified during whole genome sequencing of a cohort of children with rare speech disorders. To gain a comprehensive view of features associated with disruption of this gene, we use a genotype-driven approach, collecting and characterizing 35 individuals with de novo CHD3 mutations and overlapping phenotypes. Most mutations cluster within the ATPase/helicase domain of the encoded protein. Modeling their impact on the three-dimensional structure demonstrates disturbance of critical binding and interaction motifs. Experimental assays with six of the identified mutations show that a subset directly affects ATPase activity, and all but one yield alterations in chromatin remodeling. We implicate de novo CHD3 mutations in a syndrome characterized by intellectual disability, macrocephaly, and impaired speech and language.

7.
Am J Med Genet A ; 2018 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-30475435

RESUMO

Polyamines serve a number of vital functions in humans, including regulation of cellular proliferation, intracellular signaling, and modulation of ion channels. Ornithine decarboxylase 1 (ODC1) is the rate-limiting enzyme in endogenous polyamine synthesis. In this report, we present four patients with a distinct neurometabolic disorder associated with de novo heterozygous, gain-of-function variants in the ODC1 gene. This disorder presents with global developmental delay, ectodermal abnormalities including alopecia, absolute or relative macrocephaly, and characteristic facial dysmorphisms. Neuroimaging variably demonstrates white matter abnormalities, prominent Virchow-Robin spaces, periventricular cysts, and abnormalities of the corpus callosum. Plasma clinical metabolomics analysis demonstrates elevation of N-acetylputrescine, the acetylated form of putrescine, with otherwise normal polyamine levels. Therapies aimed at reducing putrescine levels, including ODC1 inhibitors, dietary interventions, and antibiotics to reduce polyamine production by gastrointestinal flora could be considered as disease-modifying therapies. As the ODC1 gene has been implicated in neoplasia, cancer surveillance may be important in this disorder.

8.
Mol Genet Metab ; 125(1-2): 118-126, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30031689

RESUMO

Folate metabolism in the brain is critically important and serves a number of vital roles in nucleotide synthesis, single carbon metabolism/methylation, amino acid metabolism, and mitochondrial translation. Genetic defects in almost every enzyme of folate metabolism have been reported to date, and most have neurological sequelae. We report 2 patients presenting with a neurometabolic disorder associated with biallelic variants in the MTHFS gene, encoding 5,10-methenyltetrahydrofolate synthetase. Both patients presented with microcephaly, short stature, severe global developmental delay, progressive spasticity, epilepsy, and cerebral hypomyelination. Baseline CSF 5-methyltetrahydrolate (5-MTHF) levels were in the low-normal range. The first patient was treated with folinic acid, which resulted in worsening cerebral folate deficiency. Treatment in this patient with a combination of oral L-5-methyltetrahydrofolate and intramuscular methylcobalamin was able to increase CSF 5-MTHF levels, was well tolerated over a 4 month period, and resulted in subjective mild improvements in functioning. Measurement of MTHFS enzyme activity in fibroblasts confirmed reduced activity. The direct substrate of the MTHFS reaction, 5-formyl-THF, was elevated 30-fold in patient fibroblasts compared to control, supporting the hypothesis that the pathophysiology of this disorder is a manifestation of toxicity from this metabolite.

9.
Mov Disord Clin Pract ; 5(2): 149-155, 2018 Mar-Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29930972

RESUMO

Background: Movement disorders are a significant clinical problem in lysosomal storage diseases (LSD) and account for substantial morbidity. The spectrum of movement disorders in childhood-onset LSD, however, remains poorly defined. Objectives: To define the spectrum of movement disorders in a well-characterized cohort of children with LSD. Methods: A retrospective chart review at a single tertiary care center (Boston Children's Hospital, Boston, MA, USA). Patients up to the age of 18 years with a clinical, genetic and/or biochemical diagnosis of an LSD and at least one predefined movement disorder (parkinsonism, dystonia, ataxia, tremor, chorea, myoclonus, ballism, restless leg syndrome) were included. Results: 96 patients were identified and 76 patients had a sufficiently document biochemical and/or genetic diagnosis. Of these, 18 patients met inclusion criteria (mean age: 10.3±5.8 (SD) years, range: 3-18 years; 72% male). The most common LSD associated with a movement disorder was Niemann-Pick disease type C (NPC), followed by several types of neuronal ceroid lipofuscinosis (NCL) and different mucopolysaccharidoses. The most common movement disorder was ataxia followed by rest tremor, dystonia and myoclonus. The other predefined movement disorders were rare. The majority of patients presented with more than one movement disorder. The movement disorder was slowly progressive in all patients. Brain MRI changes included diffuse cerebral volume loss, white matter abnormalities with thinning of the corpus callosum, and cerebellar atrophy. Conclusions: Movement disorders develop in a significant number of LSD patients. Ataxia, often in patients with NPC and NCL, is the most common phenotype but significant heterogeneity exists within and between different LSD.

10.
Mol Genet Metab ; 124(2): 161-167, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29685658

RESUMO

Congenital disorders of manganese metabolism are rare occurrences in children, and medical management of these disorders is complex and challenging. Homozygous exonic mutations in the manganese transporter SLC39A14 have recently been associated with a pediatric-onset neurodegenerative disorder characterized by brain manganese accumulation and clinical signs of manganese neurotoxicity, including parkinsonism-dystonia. We performed whole exome sequencing on DNA samples from two unrelated female children from the United Arab Emirates with progressive movement disorder and brain mineralization, identified a novel homozygous intronic mutation in SLC39A14 in both children, and demonstrated that the mutation leads to aberrant splicing. Both children had consistently elevated serum manganese levels and were diagnosed with SLC39A14-associated manganism. Over a four-year period, we utilized a multidisciplinary management approach for Patient 1 combining decreased manganese dietary intake and chelation with symptomatic management of dystonia. Our treatment strategy appeared to slow disease progression, but did not lead to a cure or reversal of already established deficits. Clinicians should consider testing for noncoding mutations in the diagnosis of congenital disorders of manganese metabolism and utilizing multidisciplinary approaches in the management of these disorders.

12.
Ann Neurol ; 83(6): 1089-1095, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29518281

RESUMO

VPS13 protein family members VPS13A through VPS13C have been associated with various recessive movement disorders. We describe the first disease association of rare recessive VPS13D variants including frameshift, missense, and partial duplication mutations with a novel complex, hyperkinetic neurological disorder. The clinical features include developmental delay, a childhood onset movement disorder (chorea, dystonia, or tremor), and progressive spastic ataxia or paraparesis. Characteristic brain magnetic resonance imaging shows basal ganglia or diffuse white matter T2 hyperintensities as seen in Leigh syndrome and choreoacanthocytosis. Muscle biopsy in 1 case showed mitochondrial aggregates and lipidosis, suggesting mitochondrial dysfunction. These findings underline the importance of the VPS13 complex in neurological diseases and a possible role in mitochondrial function. Ann Neurol 2018;83:1089-1095.

13.
Eur J Paediatr Neurol ; 22(3): 544-547, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29500071

RESUMO

GLUT1 deficiency syndrome (GLUT1DS) is a well described neurometabolic disorder that results from impaired glucose transport into the central nervous system. GLUT1DS classically presents with infantile-onset epilepsy, progressive microcephaly, developmental delay, ataxia, dystonia, and spasticity, but a minority of patients may manifest with paroxysmal non-epileptic phenomena including hemiparesis (Wang et al., 2002). We report for the first time cerebral perfusion changes during an acute episode of hemiparesis in a 9 year old child with GLUT1DS. The patient presented as a code stroke with her second episode of acute-onset left hemiparesis and altered mental status. Emergency MRI of brain demonstrated normal diffusion-weighted imaging, but arterial spin label perfusion weighted imaging (ASL-PWI) showed regional hypoperfusion of the right cerebral hemisphere and magnetic resonance angiography (MRA) revealed distally restricted flow related enhancement in the right MCA. The patient's deficits resolved entirely within several hours from onset. Repeat MRI one month later was normal. Our report suggests that GLUT1DS-related hemiplegic events are associated with transient lateralized cerebrovascular hypoperfusion similar to that described in hemiplegic migraine and other pediatric stroke mimics. The underlying pathophysiology for this phenomenon in GLUT1DS is not known, but may relate to cortical energy failure or abnormal cerebral microvasculature.


Assuntos
Isquemia Encefálica/etiologia , Erros Inatos do Metabolismo dos Carboidratos/complicações , Hemiplegia/etiologia , Proteínas de Transporte de Monossacarídeos/deficiência , Isquemia Encefálica/fisiopatologia , Erros Inatos do Metabolismo dos Carboidratos/fisiopatologia , Criança , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Hemiplegia/fisiopatologia , Humanos
14.
Epilepsia ; 59(2): 389-402, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29315614

RESUMO

OBJECTIVE: Pathogenic SLC6A1 variants were recently described in patients with myoclonic atonic epilepsy (MAE) and intellectual disability (ID). We set out to define the phenotypic spectrum in a larger cohort of SCL6A1-mutated patients. METHODS: We collected 24 SLC6A1 probands and 6 affected family members. Four previously published cases were included for further electroclinical description. In total, we reviewed the electroclinical data of 34 subjects. RESULTS: Cognitive development was impaired in 33/34 (97%) subjects; 28/34 had mild to moderate ID, with language impairment being the most common feature. Epilepsy was diagnosed in 31/34 cases with mean onset at 3.7 years. Cognitive assessment before epilepsy onset was available in 24/31 subjects and was normal in 25% (6/24), and consistent with mild ID in 46% (11/24) or moderate ID in 17% (4/24). Two patients had speech delay only, and 1 had severe ID. After epilepsy onset, cognition deteriorated in 46% (11/24) of cases. The most common seizure types were absence, myoclonic, and atonic seizures. Sixteen cases fulfilled the diagnostic criteria for MAE. Seven further patients had different forms of generalized epilepsy and 2 had focal epilepsy. Twenty of 31 patients became seizure-free, with valproic acid being the most effective drug. There was no clear-cut correlation between seizure control and cognitive outcome. Electroencephalography (EEG) findings were available in 27/31 patients showing irregular bursts of diffuse 2.5-3.5 Hz spikes/polyspikes-and-slow waves in 25/31. Two patients developed an EEG pattern resembling electrical status epilepticus during sleep. Ataxia was observed in 7/34 cases. We describe 7 truncating and 18 missense variants, including 4 recurrent variants (Gly232Val, Ala288Val, Val342Met, and Gly362Arg). SIGNIFICANCE: Most patients carrying pathogenic SLC6A1 variants have an MAE phenotype with language delay and mild/moderate ID before epilepsy onset. However, ID alone or associated with focal epilepsy can also be observed.


Assuntos
Epilepsias Mioclônicas/fisiopatologia , Proteínas da Membrana Plasmática de Transporte de GABA/genética , Deficiência Intelectual/fisiopatologia , Transtornos do Desenvolvimento da Linguagem/fisiopatologia , Adolescente , Adulto , Anticonvulsivantes/uso terapêutico , Ataxia/complicações , Ataxia/genética , Ataxia/fisiopatologia , Criança , Pré-Escolar , Estudos de Coortes , Eletroencefalografia , Epilepsias Mioclônicas/complicações , Epilepsias Mioclônicas/tratamento farmacológico , Epilepsias Mioclônicas/genética , Epilepsias Parciais/complicações , Epilepsias Parciais/tratamento farmacológico , Epilepsias Parciais/genética , Epilepsias Parciais/fisiopatologia , Epilepsia Generalizada/complicações , Epilepsia Generalizada/tratamento farmacológico , Epilepsia Generalizada/genética , Epilepsia Generalizada/fisiopatologia , Feminino , Estudos de Associação Genética , Humanos , Deficiência Intelectual/complicações , Deficiência Intelectual/genética , Transtornos do Desenvolvimento da Linguagem/complicações , Transtornos do Desenvolvimento da Linguagem/genética , Masculino , Mutação , Mutação de Sentido Incorreto , Transtornos do Neurodesenvolvimento/complicações , Transtornos do Neurodesenvolvimento/genética , Fenótipo , Resultado do Tratamento , Ácido Valproico/uso terapêutico , Adulto Jovem
15.
Pediatr Emerg Care ; 34(6): e115-e119, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29135898

RESUMO

Inborn errors of metabolism (IEMs) are genetic disorders that disrupt enzyme activity, cellular transport, or energy production. They are individually rare but collectively have an incidence of 1:1000. Most patients with IEMs are followed up by a physician with expertise in biochemical genetics (metabolism), but may present outside this setting. Because IEMs can present acutely with life-threatening crises that require specific interventions, it is critical for the emergency physician, internist, and critical care physician as well as the biochemical geneticist to have information on the initial assessment and management of patients with these disorders. Appropriate early care can be lifesaving. This protocol is not designed to replace the expert consultation of a biochemical geneticist, but rather to improve early care and increase the level of comfort of the acute care physician with initial management of urea cycle disorders until specialty consultation is obtained.


Assuntos
Cuidados Críticos/métodos , Distúrbios Congênitos do Ciclo da Ureia/terapia , Doença Aguda/terapia , Gerenciamento Clínico , Humanos , Médicos , Guias de Prática Clínica como Assunto , Encaminhamento e Consulta
16.
JIMD Rep ; 40: 17-22, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-28887792

RESUMO

Ornithine transcarbamylase deficiency (OTCD) is an X-linked urea cycle disorder with variable expressivity in heterozygous females. While liver function testing is often abnormal in patients with OTCD, liver failure is uncommon on presentation. A 13-month-old female with no significant past medical history presented with irritability, right arm weakness, and decreased appetite. Initial workup revealed hepatic dysfunction with an INR of 3.4, ammonia level of 75 µmol/L, and abnormal brain MRI with gyral edema with restricted diffusion, and patchy signal abnormality in basal ganglia. The MRI findings led to a putative diagnosis of acute disseminated encephalomyelitis prompting corticosteroid treatment. As steroid treatment was begun, she developed significant hepatocellular dysfunction with ALT 2,222 U/L, AST 630 U/L, prolonged INR, and elevated ammonia (213 µmol/L). Neurologic signs resolved and her ammonia level decreased (43 µmol/L) without further intervention; however, she had ongoing acute liver failure with coagulopathy and episodic irritability, managed as seronegative autoimmune hepatitis with partial response to corticosteroid therapy. At 18 months of age she presented with severe irritability with markedly increased ammonia (417 µmol/L). Plasma amino acids obtained several days prior to this acute episode demonstrated elevation in glutamine (2,725 µmol/L) and alanine (1,459 µmol/L). Biochemical testing demonstrated elevation of urine orotic acid (>240.6 mmol/mol creatinine). Genetic testing confirmed a heterozygous nonsense mutation in the OTC gene (c.958C>T, R320X). After treatment with ammonia scavengers and a protein-restricted diet, hepatic function normalized and irritability resolved. The diagnosis of a urea cycle disorder should be considered in patients with unexplained hepatic dysfunction.

17.
JIMD Rep ; 39: 45-54, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-28726122

RESUMO

Beta-ketothiolase (mitochondrial acetoacetyl-CoA thiolase) deficiency is a genetic disorder characterized by impaired isoleucine catabolism and ketone body utilization that predisposes to episodic ketoacidosis. It results from biallelic pathogenic variants in the ACAT1 gene, encoding mitochondrial beta-ketothiolase. We report two cases of beta-ketothiolase deficiency presenting with acute ketoacidosis and "metabolic stroke." The first patient presented at 28 months of age with metabolic acidosis and pallidal stroke in the setting of a febrile gastrointestinal illness. Although 2-methyl-3-hydroxybutyric acid and trace quantities of tiglylglycine were present in urine, a diagnosis of glutaric acidemia type I was initially suspected due to the presence of glutaric and 3-hydroxyglutaric acids. A diagnosis of beta-ketothiolase deficiency was ultimately made through whole exome sequencing which revealed compound heterozygous variants in ACAT1. Fibroblast studies for beta-ketothiolase enzyme activity were confirmatory. The second patient presented at 6 months of age with ketoacidosis, and was found to have elevations of urinary 2-methyl-3-hydroxybutyric acid, 2-methylacetoacetic acid, and tiglylglycine. Sequencing of ACAT1 demonstrated compound heterozygous presumed causative variants. The patient exhibited choreoathethosis 2 months after the acute metabolic decompensation. These cases highlight that, similar to a number of other organic acidemias and mitochondrial disorders, beta-ketothiolase deficiency can present with metabolic stroke. They also illustrate the variability in clinical presentation, imaging, and biochemical evaluation that make screening for and diagnosis of this rare disorder challenging, and further demonstrate the value of whole exome sequencing in the diagnosis of metabolic disorders.

18.
Pediatr Emerg Care ; 34(1): 64-67, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29095391

RESUMO

Inborn errors of metabolism (IEMs) are genetic disorders that disrupt enzyme activity, cellular transport, or energy production. They are individually rare but collectively have an incidence of 1:1000. Most patients with IEMs are followed up by a physician with expertise in biochemical genetics (metabolism), but may present outside this setting. Because IEMs can present acutely with life-threatening crises that require specific interventions, it is critical for the emergency medicine physician, pediatrician, internist, and critical care physician as well as the biochemical geneticist to have information on the initial assessment and management of patients with these disorders. Appropriate early care can be lifesaving. This protocol is not designed to replace the expert consultation of a biochemical geneticist, but rather to improve early care and increase the level of comfort of the acute care physician with initial management of maple syrup urine disease until specialty consultation is obtained.


Assuntos
Doença Aguda/terapia , Doença da Urina de Xarope de Bordo/terapia , Algoritmos , Medicina de Emergência/métodos , Humanos , Doença da Urina de Xarope de Bordo/complicações , Monitorização Fisiológica/métodos
19.
Clin Chem ; 63(11): 1771-1773, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29089323
20.
Pediatr Neurol ; 76: 47-53, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28985901

RESUMO

OBJECTIVE: Pyridoxine is converted to its biologically active form pyridoxal-5-phosphate (P5P) by the enzyme pyridox(am)ine 5'-phosphate oxidase and serves as a cofactor in nearly 200 reactions in the central nervous system. Pyridox(am)ine 5'-phosphate oxidase deficiency leads to P5P dependent epilepsy, typically a neonatal- or infantile-onset epileptic encephalopathy treatable with P5P or in some cases, pyridoxine. Following identification of retinopathy in a patient with pyridox(am)ine 5'-phosphate oxidase deficiency that was reversible with P5P therapy, we describe the systemic manifestations of pyridox(am)ine 5'-phosphate oxidase deficiency. METHODS: A series of six patients with homozygous mutations of PNPO, the gene coding pyridox(am)ine 5'-phosphate oxidase, were evaluated in our center over the course of two years for phenotyping of neurological and systemic manifestations. RESULTS: Five of six were born prematurely, three had anemia and failure to thrive, and two had elevated alkaline phosphatase. A movement disorder was observed in two children, and a reversible retinopathy was observed in the most severely affected infant. All patients had neonatal-onset epilepsy and were on a continuum of developmental delay to profound encephalopathy. Electroencephalographic features included background slowing and disorganization, absent sleep features, and multifocal and generalized epileptiform discharges. All the affected probands carried a homozygous PNPO mutation (c.674 G>T, c.686 G>A and c.352G>A). CONCLUSION: In addition to the well-described epileptic encephalopathy, pyridox(am)ine 5'-phosphate oxidase deficiency causes a range of neurological and systemic manifestations. A movement disorder, developmental delay, and encephalopathy, as well as retinopathy, anemia, and failure to thrive add to the broadening clinical spectrum of P5P dependent epilepsy.


Assuntos
Encefalopatias Metabólicas/complicações , Epilepsia/etiologia , Hipóxia-Isquemia Encefálica/complicações , Piridoxaminafosfato Oxidase/deficiência , Convulsões/complicações , Encefalopatias Metabólicas/diagnóstico por imagem , Eletroencefalografia , Feminino , Humanos , Hipóxia-Isquemia Encefálica/diagnóstico por imagem , Recém-Nascido , Imagem por Ressonância Magnética , Masculino , Mutação/genética , Fosfato de Piridoxal/líquido cefalorraquidiano , Fosfato de Piridoxal/genética , Retina/patologia , Convulsões/diagnóstico por imagem
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