Modeling Glutaric Aciduria Type I in human neuroblastoma cells recapitulates neuronal damage that can be rescued by gene replacement.

Glutaric Aciduria type I (GA1) is a rare neurometabolic disorder caused by mutations in the GDCH gene encoding for glutaryl-CoA dehydrogenase (GCDH) in the catabolic pathway of lysine, hydroxylysine and tryptophan. GCDH deficiency leads to increased concentrations of glutaric acid (GA) and 3-hydroxyglutaric acid (3-OHGA) in body fluids and tissues. These metabolites are the main triggers of brain damage. Mechanistic studies supporting neurotoxicity in mouse models have been conducted. However, the different vulnerability to some stressors between mouse and human brain cells reveals the need to have a reliable human neuronal model to study GA1 pathogenesis. In the present work we generated a GCDH knockout (KO) in the human neuroblastoma cell line SH-SY5Y by CRISPR/Cas9 technology. SH-SY5Y-GCDH KO cells accumulate GA, 3-OHGA, and glutarylcarnitine when exposed to lysine overload. GA or lysine treatment triggered neuronal damage in GCDH deficient cells. SH-SY5Y-GCDH KO cells also displayed features of GA1 pathogenesis such as increased oxidative stress vulnerability. Restoration of the GCDH activity by gene replacement rescued neuronal alterations. Thus, our findings provide a human neuronal cellular model of GA1 to study this disease and show the potential of gene therapy to rescue GCDH deficiency.

An incidental finding in newborn screening leading to the diagnosis of a patient with ECHS1 mutations.

Short-chain enoyl-CoA hydratase (ECHS1) is a mitochondrial beta-oxidation enzyme involved in the metabolism of acyl-CoA fatty acid esters, as well as in valine metabolism. ECHS1 deficiency has multiple manifestations, including Leigh syndrome early at birth or in childhood with poor prognosis, to cutis laxa, exercise-induced dystonia and congenital lactic acidosis. Here we describe the case of a newborn with mutations in ECHS1 that caught our attention after the incidental finding of 3-hydroxy-butyryl\3-hydroxy-isobutyryl\malonylcarnitine (C4OH\C3DC) and tiglylcarnitine (C5:1) on blood spot in the newborn screening (NBS) program. Diagnosis was suspected based on the analysis of organic acids on dried urine spot. A moderate increase of 2-methyl-2,3-dihydroxybutyric acid, was detected, which is a known marker of this disease. Exome analysis showed c.404A>G (p.Asn135Ser) mutation in homozygosis in the ECHS1 gene. The child was therefore admitted to the hospital. Initial examination showed little response to auditory stimuli and mild hypertonia of the extremities. Clinical deterioration was evident at 4 months of age, including neurological and cardiac involvement, and the patient died at 5 months of age. This case illustrates how an incidental detection in the NBS Program can lead to the diagnosis ECHS1 deficiency. Although it is a severe disease, with no treatment available, early detection would allow adequate genetic counseling avoiding the odyssey that suffered most of these families.

Pilot Experience with an External Quality Assurance Scheme for Acylcarnitines in Plasma/Serum.

The analysis of acylcarnitines (AC) in plasma/serum is established as a useful test for the biochemical diagnosis and the monitoring of treatment of organic acidurias and fatty acid oxidation defects. External quality assurance (EQA) for qualitative and quantitative AC is offered by ERNDIM and CDC in dried blood spots but not in plasma/serum samples. A pilot interlaboratory comparison between 14 European laboratories was performed over 3 years using serum/plasma samples from patients with an established diagnosis of an organic aciduria or fatty acid oxidation defect. Twenty-three different samples with a short clinical description were circulated. Participants were asked to specify the method used to analyze diagnostic AC, to give quantitative data for diagnostic AC with the corresponding reference values, possible diagnosis, and advice for further investigations.Although the reference and pathological concentrations of AC varied among laboratories, elevated marker AC for propionic acidemia, isovaleric acidemia, medium-chain acyl-CoA dehydrogenase, very long-chain acyl-CoA dehydrogenase, and multiple acyl-CoA dehydrogenase deficiencies were correctly identified by all participants allowing the diagnosis of these diseases. Conversely, the increased concentrations of dicarboxylic AC were not always identified, and therefore the correct diagnosis was not reach by some participants, as exemplified in cases of malonic aciduria and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency. Misinterpretation occurred in those laboratories that used multiple-reaction monitoring acquisition mode, did not derivatize, or did not separate isomers. However, some of these laboratories suggested further analyses to clarify the diagnosis.This pilot experience highlights the importance of an EQA scheme for AC in plasma.

Rare Late-Onset Presentation of Glutaric Aciduria Type I in a 16-Year-Old Woman with a Novel GCDH Mutation.

Glutaric acidemia type I (GA-I) is a treatable autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism caused by glutaryl-CoA dehydrogenase (GCDH) deficiency. Presentation and progression of disease are variable ranging from asymptomatic carrier state to catastrophic encephalopathy. GA-I usually presents before age 18 months, usually triggered by childhood infection, with mild or severe acute encephalopathy, striatal degeneration, and movement disorder, most often acute dystonia. At a presymptomatic stage diagnosis is suggested clinically by macrocephaly, radiologically by widened Sylvian fissures and biochemically by the presence of excess 3-hydroxyglutaric acid and glutaric acid in urine. Treatment consists of lysine-restricted diet and carnitine supplementation, specific diet restrictions, as well as symptomatic and anticatabolic treatment of intercurrent illness. Presymptomatic diagnosis and treatment are essential to prognosis. We report the case of 16-year-old macrocephalic female with late-onset GA-I and unusual paucisymptomatic presentation with fainting after exercise and widespread white matter signal changes at MRI. She was compound heterozygote for a novel mutation (IVS10-2A>G) affecting splicing at GCDH and a common missense mutation (c. 1240C>T; p.Arg402Trp, R402W). Interestingly, the site of the novel mutation is the nucleotide position of a common mutation found almost exclusively in patients of Chinese/Taiwanese origin (IVS10-2A>C).

Clinical and biochemical outcome after hydroxocobalamin dose escalation in a series of patients with cobalamin C deficiency.

BACKGROUND: CblC deficiency produces a combination of methylmalonic aciduria (MMA) and homocystinuria (HCU), and is the most common error of cobalamin metabolism. Patients present a wide spectrum of symptoms, ranging from early severe multisystemic forms, to milder late-onset phenotypes. Cognitive and visual impairment are nearly constant. Hydroxocobalamin (OHCbl), betaine, folinic acid, levocarnitine and eventually dietary protein restriction are the main therapeutic approaches. Although early introduction of OHCbl is crucial, no standardized protocols regarding dose adaptation exist. No reports on long-term outcomes after high doses of this vitamin have been published. METHODS: In this study five patients with CblC deficiency (early severe forms) were treated with high doses of OHCbl for 18 to 30months. Clinical examinations, neurological assessment, and biochemical studies (plasma total homocysteine (tHcy), amino acids, hydroxocobalamin, and methylmalonic acid in urine) were periodically performed. RESULTS: Variable clinical and biochemical outcomes were observed in patients treated with high doses of OHCbl. The best biochemical response was observed in those children with the worse metabolic control. By contrast, those patients with a concentration of tHcy around 50µmol/l or less showed only minor changes. Clinically, a considerable improvement was observed in those patients with severe problems in communication, expressive language and behavior. CONCLUSIONS: According to our study, high OHCbl doses in CblC deficiency could have a greater benefit in those children with a prior history of suboptimal metabolic control, and also in those with severe neurological phenotypes. More specifically, we observed improvements in communication skills and behavior. These results should encourage further prospective trials to determine the optimal OHCbl regimen and to generate protocols and guidelines in this rare disorder.

Analysis of coenzyme Q(10) in lymphocytes by HPLC-MS/MS.

Coenzyme Q(10) (CoQ(10)) deficiency syndromes are potentially treatable disorders. Skeletal muscle is the most widely accepted tissue for their study, but sampling is an invasive procedure. Cultured skin fibroblasts seem to improve the biochemical diagnosis, but their growth requires a certain period of time. Our aim was to set up a minimally invasive, fast and reliable analytical procedure to measure CoQ(10) in lymphocytes, to prevent any delay in diagnosing primary CoQ(10) deficiency. HPLC-MS/MS analysis of CoQ(10) showed high sensitivity and specificity. The reference range was established in apparently healthy volunteers (n=33); the mean of CoQ(10) in lymphocytes was 107nmol/g protein (95% confidence interval: 105-120) and 2.0nmol/UCS (95% confidence interval: 2.06-2.46). Therefore, the range was narrower when normalized to units of citrate synthase (UCS) than when normalized to grams of protein. The method was linear from 0.01 to 1µM with a good precision and sensitivity (limit of quantification 0.01µM). Intra-assay and inter-assay coefficients of variation were lower than 13%. Recovery was higher than 95%. In our hands, lymphocytes seem to be a reliable matrix as they reflect intracellular content of CoQ(10). In addition, they can be obtained by a minimally invasive procedure (venipuncture).

Relevance of expanded neonatal screening of medium-chain acyl co-a dehydrogenase deficiency: outcome of a decade in galicia (Spain).

Neonatal screening of medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is of major importance due to the significant morbidity and mortality in undiagnosed patients. MCADD screening has been performed routinely in Galicia since July 2000, and until now 199,943 newborns have been screened. We identified 11 cases of MCADD, which gives an incidence of 1/18,134. During this period, no false negative screens have been detected. At diagnosis, all identified newborns were asymptomatic. Our data showed that octanoylcarnitine (C8) and C8/C10 ratio are the best markers for screening of MCADD. C8 was increased in all patients and C8/C10 was increased in all but one patient.The common mutation, c.985A > G, was found in homozygosity in seven newborns and in compound heterozygosity in three, while one patient did not carry the common mutation at all. In addition, two novel mutations c.245G > C (p.W82S) and c.542A > G (p.D181G) were identified. Ten of the 11 identified newborns did not experience any episodes of decompensation. The patient with the highest level of medium chain acylcarnitines at diagnosis, who was homozygous for the c.985A > G mutation, died at the age of 2 years due to a severe infection.This is the first report of the results from neonatal screening for MCADD in Spain. Our data provide further evidence of the benefits of MCADD screening and contribute to better understanding of this disease.

Response to creatine analogs in fibroblasts and patients with creatine transporter deficiency.

Creatine transporter (CRTR) deficiency is one of the most frequent causes of X-linked mental retardation. The lack of an effective treatment for this disease, in contrast to creatine (Cr) biosynthesis disorders that respond to Cr monohydrate (CM), led us to analyze the efficacy of a lipophilic molecule derived from Cr, creatine ethyl ester (CEE), in fibroblasts and patients with CRTR deficiency. CM and CEE uptake studies were performed in six controls and four fibroblast cell lines from patients. We found a significant increase in Cr uptake after 72 h of incubation with CEE (500 micromol/L) in patients and control fibroblasts compared to incubation with CM. Subsequently, we assayed the clinical effect of CEE administration in four patients with CRTR deficiency. After 1 year of treatment, a lack of significant improvement in neuropsychological assessment or changes in Cr level in brain (1)H MRS was observed, and CEE was discontinued. In conclusion, this 12-month trial with CEE did not increase the brain concentration of Cr. Our in vitro data lend support to the idea of a certain passive transport of CEE in both pathological and control cells, although more lipophilic molecules or other cell systems that mimic the BBB should be used for a better approach to the in vivo system.

Classic and late-onset neurological disease in two siblings with glutaryl-CoA dehydrogenase deficiency.

Late-onset neurological disease has rarely been reported in patients with glutaryl-CoA dehydrogenase (GCDH) deficiency. We present two siblings with GCDH deficiency. One of them presented with the classic neurological disease (patient 1). Routine investigation of family members revealed that her apparently unharmed 13-year-old sister was also affected (patient 2). Patient 2 started to have academic difficulties in the months prior to our assessment. Her clinical examination was normal, with the exception of a cranial circumference of 57 cm (slightly over the 98 th centile). A severe leukoencephalopathy was demonstrated on MRI. Neuropsychological assessment showed an IQ within the normal-low range and a mild impairment of memory and executive function. Previous reports on late-onset neurological disease in GCDH deficiency have revealed that progressive leukoencephalopathy develops over time. Following the recently published guideline for the diagnosis and management of GCDH deficiency, both patients are receiving dietary treatment in combination with L-carnitine supplementation. We emphasize the need to search for chronic neurological changes of late-onset type in apparently unaffected GCDH deficiency cases diagnosed in routine family investigations.

Aciduria glutárica tipo I con fenotipo bioquímico de baja excreción asociado a una nueva mutación / Glutaric aciduria type I with a low-excretion biochemical phenotype associated to a new mutation

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[Glutaric aciduria type I. Clinical, biochemical and molecular findings in six patients in Venezuela]. / Aciduria glutárica tipo I. Hallazgos clínicos, bioquímicos y moleculares en seis pacientes venezolanos.

INTRODUCTION: Glutaric aciduria type I is an autosomal recessive inborn error of metabolism that is due to a deficiency of the enzyme glutaryl-CoA dehydrogenase, which gives rise to an accumulation of glutaric and 3-hydroxyglutaric acids in biological fluids. Clinical features present as a sudden-onset severe neurological disorder, characterised by extrapyramidal signs (dystonia-dyskinesia), hypotonia, irritability, macrocephaly and degeneration of the basal ganglia; it may also manifest with unspecific symptoms, such as hypotonia and psychomotor retardation. AIMS: To describe the clinical, biochemical, neuroimaging and molecular aspects in six Venezuelan patients and to highlight the importance of an early diagnosis of glutaric aciduria type I so as to be able to establish early treatment and thus prevent the neurological damage produced by this disease. CASE REPORTS: Two patients were referred because of macrocephaly, hypotonia and psychomotor retardation, and four more following an encephalopathic crisis. In all of them, neuroimaging studies showed delays in myelination, bilateral frontotemporal hypoplasia and symmetric widening of the Sylvian fissures with poor opercularisation. Urinary organic acid analyses showed raised levels of glutaric and 3-hydroxyglutaric acids, and a molecular analysis confirmed the diagnosis. CONCLUSIONS: Organic acid analysis should be indicated in all patients who present macrocephaly, hypotonia, psychomotor retardation or an encephalopathic crisis of unknown causation. This study allowed us to determine the behaviour of the disease in Venezuela, since no epidemiological data exist in the country.

Aciduria glutárica tipo I. Hallazgos clínicos, bioquímicos y moleculares en seis pacientes venezolanos / Glutaric aciduria type I. Clinical, biochemical and molecular findings in six patients in Venezuela

Introducción. La aciduria glutárica tipo I es un error congénito del metabolismo, con herencia autosómica recesiva, debido a la deficiencia de la enzima glutaril-CoA deshidrogenasa, que da lugar a la acumulación de ácido glutárico y 3-hidroxiglutárico en fluidos biológicos. El cuadro clínico se presenta como un trastorno neurológico grave, de inicio súbito, caracterizado por signos extrapiramidales (distonía-discinesia), hipotonía, irritabilidad, macrocefalia y degeneración de los ganglios basales; o puede manifestarse con síntomas inespecíficos, como hipotonía y retraso psicomotor. Objetivos. Describir los aspectos clínicos, bioquímicos, de neuroimagen y moleculares en seis pacientes venezolanos y resaltar la importancia del diagnóstico precoz de la aciduria glutárica tipo I para instaurar tratamiento temprano y evitar el daño neurológico que esta enfermedad produce. Casos clínicos. Se remitieron dos pacientes por macrocefalia, hipotonía y retraso psicomotor, y cuatro posteriores a una crisis encefalopática. Los estudios de neuroimagen mostraron en todos ellos retraso en la mielinización, hipoplasia frontotemporal bilateral y ensanchamiento simétrico de las cisuras de Silvio con pobre opercularización. El análisis de ácidos orgánicos en orina mostró niveles incrementados de los ácidos glutárico y 3-hidroxiglutárico, y el análisis molecular permitió la confirmación del diagnóstico. Conclusiones. En todo paciente que se presenta con macrocefalia, hipotonía, retraso psicomotor o una crisis encefalopática sin causa determinada debe indicarse el análisis de ácidos orgánicos. Este estudio permitió conocer el comportamiento de la enfermedad en Venezuela, ya que no existen datos epidemiológicos en el país

Introduction. Glutaric aciduria type I is an autosomal recessive inborn error of metabolism that is due to a deficiency of the enzyme glutaryl-CoA dehydrogenase, which gives rise to an accumulation of glutaric and 3-hydroxyglutaric acids in biological fluids. Clinical features present as a sudden-onset severe neurological disorder, characterised by extrapyramidal signs (dystonia-dyskinesia), hypotonia, irritability, macrocephaly and degeneration of the basal ganglia; it may also manifest with unspecific symptoms, such as hypotonia and psychomotor retardation. Aims. To describe the clinical, biochemical, neuroimaging and molecular aspects in six Venezuelan patients and to highlight the importance of an early diagnosis of glutaric aciduria type I so as to be able to establish early treatment and thus prevent the neurological damage produced by this disease. Case reports. Two patients were referred because of macrocephaly, hypotonia and psychomotor retardation, and four more following an encephalopathic crisis. In all of them, neuroimaging studies showed delays in myelination, bilateral frontotemporal hypoplasia and symmetric widening of the Sylvian fissures with poor opercularisation. Urinary organic acid analyses showed raised levels of glutaric and 3-hydroxyglutaric acids, and a molecular analysis confirmed the diagnosis. Conclusions. Organic acid analysis should be indicated in all patients who present macrocephaly, hypotonia, psychomotor retardation or an encephalopathic crisis of unknown causation. This study allowed us to determine the behaviour of the disease in Venezuela, since no epidemiological data exist in the country