[McArdle's disease revealed by acute low back pain]. / Une maladie de McArdle révélée par une lombalgie aiguë.

INTRODUCTION: McArdle disease, or glycogen storage disease type V (GSD 5), is a rare metabolic myopathy linked to an autosomal recessive myophosphorylase deficiency. CASE REPORT: We report the case of a 17-year-old male patient who was referred to the emergency department for the management of acute inflammatory low back pain, without traumatic context, associated with an increase of CK at 66,336 UI/L (N<192UI/L) and a CRP at 202mg/L. The immunological assessment was negative and the spinal MRI showed images in favor of necrotizing fasciitis affecting the erector spinae muscles, among others. Faced with the description of difficulties in practicing physical activities since childhood and a non-ischaemic forearm exercise test showing no elevation in lactacidemia, genetic tests were carried out, finding two heterozygous variants in the PYGM gene: c.1963G>A (p.Glu655Lys) class 5 and c.2178-1G>A class 4, confirming the diagnosis of McArdle disease. DISCUSSION: GSD 5 is a disease characterized essentially by muscular fatigability during exercise. The case reported here is original in the clinical circumstances leading to the diagnosis, i.e., inaugural acute low back pain with rhabdomyolysis. This symptomatology had already been described before, but in a patient whose diagnosis was already known. Spinal MRI showed non-specific muscle inflammation and necrosis. Muscle biopsy only found necrosis but no pathological elements typical of the diagnosis. If the symptoms are suggestive, it may be preferable to directly perform a non-ischaemic forearm exercise test, in order to go directly to molecular genetic analysis. There is no specific curative treatment of GSD 5. However, some measures can be implemented to limit the symptoms, such as learning physical exercises, limiting intense efforts and adopting dietary recommendations.

Treatment of hereditary amyotrophic lateral sclerosis.

Currently, only four molecules can be prescribed for amyotrophic lateral sclerosis (ALS), of which only one is approved worldwide for this indication, riluzole. Although progress in the therapeutic field remains unsatisfactory, we have to notice that genetics have undergone impressive improvements over the last three decades and, by extension, our knowledge of ALS cases linked to a pathogenic mutation that accounts for 10% of all cases (either sporadic or familiar) and is currently called hereditary ALS (hALS). In many neurological diseases treatment targeting pathogenic genes have significatively improved the natural profile of the disease: this is perfectly illustrated for familial amyloid neuropathy and spinal muscular atrophy. Because of these findings and the urgent need to find a cure for ALS, many trials have focused on familial ALS targeting the four most important genes linked to the disease: C9orf72, SOD1, TARDBP and FUS. We propose in this review an update on the perspectives of treatment that may be available in mid-term in hALS and will discuss in the last part the potential consequences for asymptomatic relatives of patients with a hALS and for ALS patients.

[Fish odor syndrome: A socially disabling disorder]. / Le « Fish odor syndrome ¼ : une maladie socialement invalidante.

INTRODUCTION: Fish odor syndrome (FOS) is a rare metabolic disorder that manifests as "rotten fish" body odor and is caused by the excretion of trimethylamine (TMA) in body fluids. This disease can have a negative impact on the social life of affected patients. CASE REPORTS: We report the case of two female patients complaining about unpleasant body odor. The diagnosis of FOS was confirmed by the demonstration of trimethylaminuria by NMR spectroscopy and by molecular analysis of the FMO3 gene. A restrictive choline diet combined with digestive decontamination reduced odor symptoms and improved the social life of these 2 patients. CONCLUSIONS: Fish odor syndrome is a rare and unrecognized disease that can affect the quality of life of affected persons. Following laboratory diagnosis, treatment is often effective.

Primary Lateral Sclerosis: Clinical, radiological and molecular features.

Primary Lateral Sclerosis (PLS) is an uncommon motor neuron disorder. Despite the well-recognisable constellation of clinical manifestations, the initial diagnosis can be challenging and therapeutic options are currently limited. There have been no recent clinical trials of disease-modifying therapies dedicated to this patient cohort and awareness of recent research developments is limited. The recent consensus diagnostic criteria introduced the category 'probable' PLS which is likely to curtail the diagnostic journey of patients. Extra-motor clinical manifestations are increasingly recognised, challenging the view of PLS as a 'pure' upper motor neuron condition. The post mortem literature of PLS has been expanded by seminal TDP-43 reports and recent PLS studies increasingly avail of meticulous genetic profiling. Research in PLS has gained unprecedented momentum in recent years generating novel academic insights, which may have important clinical ramifications.

Hearing loss in inherited metabolic disorders: A systematic review.

Inherited metabolic disorders (IMDs) have been observed in individuals with hearing loss (HL), but IMDs are rarely the cause of syndromic HL. With early diagnosis, management of HL is more effective and cortical reorganization is possible with hearing aids or cochlear implants. This review describes relationships between IMDs and HL in terms of incidence, etiology of HL, pathophysiology, and treatment. Forty types of IMDs are described in the literature, mainly in case reports. Management and prognosis are noted where existing. We also describe IMDs with HL given age of occurrence of HL. Reviewing the main IMDs that are associated with HL may provide an additional clinical tool with which to better diagnose syndromic HL.

Validation of plasma amino acid profile using UHPLC-mass spectrometer (QDa) as a screening method in a metabolic disorders reference centre: Performance and accreditation concerns.

INTRODUCTION: Amino acid (AA) analysis in plasma is essential for diagnosis and monitoring of inborn errors of metabolism (IEM). The efficacy of patient management is governed by the rapidity of AA profile availability, along with the robustness of the method. French quality guidelines and progress made in analytical techniques have led biologists to develop AA profile exploration via mass spectrometry (MS). OBJECTIVES: The aim of this study was to validate an analytical method with a single quadrupole mass spectrometer (MS) and to suggest reference values in regard to French quality and IEM society recommendations. DESIGN AND METHODS: Plasma samples from patients were deproteinised and derivatised with AccqTag™ reagent. Analysis was performed by reverse-phase chromatography coupled to QDA detector. We evaluated accuracy, intra-days and inter-days precision and limit of quantification by the ß-expectation tolerance interval method for 27 AA. Method comparison was performed with the standard method (ion exchange chromatography, IEC) on Jeol Aminotac® and to tandem MS. Reference values were established on AA concentrations of the cohort of patients who had no IEM. RESULTS: Our method allowed the separations of almost all amino acids with a total run time of 12 min. Separation of isoleucine and alloisoleucine was incomplete (R = 0.55) but without impact on biological interpretation. Precision, accuracy and quantification were satisfactory (intra-days coefficient of variation (CV) was <5%, inter-days precision CV <10% and accuracy <15%). The limits of quantification were validated between 1 and 900 µmol/L. Results were comparable between the new method and IEC. CONCLUSION: Ultimately, we validated a rapid method on plasma for quantifying 27 amino acids that can be used in routine practice, according to French quality laboratories and SFEIM (French Society of Inborn Error of Metabolism) recommendations. Furthermore, estimated reference values were similar to those found in published studies focusing on other methods. Despite a lower specificity compared to tandem MS, the simplicity and rapidity of our method are the main advantage of this technique and place it as a major tool in IEM diagnosis and management.

Behavioral, Hormonal, Inflammatory, and Metabolic Effects Associated with FGF21-Pathway Activation in an ALS Mouse Model.

In amyotrophic lateral sclerosis (ALS), motor neuron degeneration occurs simultaneously with systemic metabolic dysfunction and neuro-inflammation. The fibroblast growth factor 21 (FGF21) plays an important role in the regulation of both phenomena and is a major hormone of energetic homeostasis. In this study, we aimed to determine the relevance of FGF21 pathway stimulation in a male mouse model of ALS (mutated SOD1-G93A mice) by using a pharmacological agonist of FGF21, R1Mab1. Mice (SOD1-WT and mutant SOD1-G93A) were treated with R1Mab1 or vehicle. Longitudinal data about clinical status (motor function, body weight) and biological parameters (including hormonal, immunological, and metabolomics profiles) were collected from the first symptoms to euthanasia at week 20. Multivariate models were performed to identify the main parameters associated with R1Mab1 treatment and to link them with clinical status, and metabolic pathways involving the discriminant metabolites were also determined. A beneficial clinical effect of R1Mab1 was revealed on slow rotarod (p = 0.032), despite a significant decrease in body weight of ALS mice (p < 0.001). We observed a decrease in serum TNF-α, MCP-1, and insulin levels (p = 0.0059, p = 0.003, and p = 0.01, respectively). At 16 weeks, metabolomics analyses revealed a clear discrimination (CV-ANOVA = 0.0086) according to the treatment and the most discriminant pathways, including sphingolipid metabolism, butanoate metabolism, pantothenate and CoA biosynthesis, and the metabolism of amino acids like tyrosine, arginine, proline, glycine, serine, alanine, aspartate, and glutamate. Mice treated with R1Mab1 had mildly higher performance on slow rotarod despite a decrease on body weight and could be linked with the anti-inflammatory effect of R1Mab1. These results indicate that FGF21 pathway is an interesting target in ALS, with a slight improvement in motor function combined with metabolic and anti-inflammatory effects.

The specific metabolome profiling of patients infected by SARS-COV-2 supports the key role of tryptophan-nicotinamide pathway and cytosine metabolism.

The biological mechanisms involved in SARS-CoV-2 infection are only partially understood. Thus we explored the plasma metabolome of patients infected with SARS-CoV-2 to search for diagnostic and/or prognostic biomarkers and to improve the knowledge of metabolic disturbance in this infection. We analyzed the plasma metabolome of 55 patients infected with SARS-CoV-2 and 45 controls by LC-HRMS at the time of viral diagnosis (D0). We first evaluated the ability to predict the diagnosis from the metabotype at D0 in an independent population. Next, we assessed the feasibility of predicting the disease evolution at the 7th and 15th day. Plasma metabolome allowed us to generate a discriminant multivariate model to predict the diagnosis of SARS-CoV-2 in an independent population (accuracy > 74%, sensitivity, specificity > 75%). We identified the role of the cytosine and tryptophan-nicotinamide pathways in this discrimination. However, metabolomic exploration modestly explained the disease evolution. Here, we present the first metabolomic study in SARS-CoV-2 patients which showed a high reliable prediction of early diagnosis. We have highlighted the role of the tryptophan-nicotinamide pathway clearly linked to inflammatory signals and microbiota, and the involvement of cytosine, previously described as a coordinator of cell metabolism in SARS-CoV-2. These findings could open new therapeutic perspectives as indirect targets.

Advances in disease-modifying pharmacotherapies for the treatment of amyotrophic lateral sclerosis.

INTRODUCTION: To date, riluzole and edaravone are the only two drugs that have successfully passed clinical trials for the treatment of Amyotrophic Lateral Sclerosis (ALS). Unfortunately, both drugs exhibit very modest effects. Most other drugs have failed at phase III to show significant effects in phase III when tested in larger cohorts. This pattern necessitates improvements in the approach to ALS pharmacotherapy. AREAS COVERED: The authors discuss the two approved drugs, as well as several examples of drug candidates whose clinical trials did not demonstrate efficacy in phase III. Post-hoc analyses reveal that future clinical trials should include disease-staging procedures, longer-term trials to correctly assess survival, genetic studies of participants to aid in stratification, and more similarity between the protocols on preclinical models and clinical trials. Finally, they discuss the trials in process that demonstrate some of these suggestions and improvements. EXPERT OPINION: The approval of riluzole and edaravone was essentially a desperate attempt to provide urgent pharmacotherapy to the ALS community. To evolve toward more efficient therapies, we must conduct clinical trials with optimal stratification based on rapid/slow progressors and cognitive decline. Pharmaco-metabolomics should allow for the identification of biomarkers that are adapted for a given drug.

Typical bulbar ALS can be linked to GARS mutation.

Background: Amyotrophic lateral sclerosis is the most frequent motor neuron disorders (MND) in adults. The role of genetic factors is worldwide accepted, and currently, more than 30 genes have been linked to this disease. Genetics was also the matter of numerous studies in distal hereditary motor neuropathies (dHMN). GARS is classically linked to a predominant dHMN and, until now, no mutation has been described in GARS in other MND. Case Report: We report the case of a 70-year-old woman who developed a classical bulbar ALS phenotype. Owing to his familial history of ALS, a genetic screening was performed excluding the main genes linked to ALS and revealing a heterozygous missense mutation in GARS gene with a high probability of pathogenicity. Conclusion: This first description of mutation in GARS in ALS, extends once more the genetic overlap between ALS and other MND.

Causative Genes in Amyotrophic Lateral Sclerosis and Protein Degradation Pathways: a Link to Neurodegeneration.

Amyotrophic lateral sclerosis (ALS) is a disease caused by the degeneration of motor neurons (MNs) leading to progressive muscle weakness and atrophy. Several molecular pathways have been implicated, such as glutamate-mediated excitotoxicity, defects in cytoskeletal dynamics and axonal transport, disruption of RNA metabolism, and impairments in proteostasis. ALS is associated with protein accumulation in the cytoplasm of cells undergoing neurodegeneration, which is a hallmark of the disease. In this review, we focus on mechanisms of proteostasis, particularly protein degradation, and discuss how they are related to the genetics of ALS. Indeed, the genetic bases of the disease with the implication of more than 30 genes associated with familial ALS to date, together with the important increase in understanding of endoplasmic reticulum (ER) stress, proteasomal degradation, and autophagy, allow researchers to better understand the mechanisms underlying the selective death of motor neurons in ALS. It is clear that defects in proteostasis are involved in this type of cellular degeneration, but whether or not these mechanisms are primary causes or merely consequential remains to be clearly demonstrated. Novel cellular and animal models allowing chronic expression of mutant proteins, for example, are required. Further studies linking genetic discoveries in ALS to mechanisms of protein clearance will certainly be crucial in order to accelerate translational and clinical research towards new therapeutic targets and strategies.

The combination of four analytical methods to explore skeletal muscle metabolomics: Better coverage of metabolic pathways or a marketing argument?

OBJECTIVES: Metabolomics is an emerging science based on diverse high throughput methods that are rapidly evolving to improve metabolic coverage of biological fluids and tissues. Technical progress has led researchers to combine several analytical methods without reporting the impact on metabolic coverage of such a strategy. The objective of our study was to develop and validate several analytical techniques (mass spectrometry coupled to gas or liquid chromatography and nuclear magnetic resonance) for the metabolomic analysis of small muscle samples and evaluate the impact of combining methods for more exhaustive metabolite covering. DESIGN AND METHODS: We evaluated the muscle metabolome from the same pool of mouse muscle samples after 2 metabolite extraction protocols. Four analytical methods were used: targeted flow injection analysis coupled with mass spectrometry (FIA-MS/MS), gas chromatography coupled with mass spectrometry (GC-MS), liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), and nuclear magnetic resonance (NMR) analysis. We evaluated the global variability of each compound i.e., analytical (from quality controls) and extraction variability (from muscle extracts). We determined the best extraction method and we reported the common and distinct metabolites identified based on the number and identity of the compounds detected with low analytical variability (variation coefficient<30%) for each method. Finally, we assessed the coverage of muscle metabolic pathways obtained. RESULTS: Methanol/chloroform/water and water/methanol were the best extraction solvent for muscle metabolome analysis by NMR and MS, respectively. We identified 38 metabolites by nuclear magnetic resonance, 37 by FIA-MS/MS, 18 by GC-MS, and 80 by LC-HRMS. The combination led us to identify a total of 132 metabolites with low variability partitioned into 58 metabolic pathways, such as amino acid, nitrogen, purine, and pyrimidine metabolism, and the citric acid cycle. This combination also showed that the contribution of GC-MS was low when used in combination with other mass spectrometry methods and nuclear magnetic resonance to explore muscle samples. CONCLUSION: This study reports the validation of several analytical methods, based on nuclear magnetic resonance and several mass spectrometry methods, to explore the muscle metabolome from a small amount of tissue, comparable to that obtained during a clinical trial. The combination of several techniques may be relevant for the exploration of muscle metabolism, with acceptable analytical variability and overlap between methods However, the difficult and time-consuming data pre-processing, processing, and statistical analysis steps do not justify systematically combining analytical methods.

Lipidomics Reveals Cerebrospinal-Fluid Signatures of ALS.

Amyotrophic lateral sclerosis (ALS), the commonest adult-onset motor neuron disorder, is characterized by a survival span of only 2-5 years after onset. Relevant biomarkers or specific metabolic signatures would provide powerful tools for the management of ALS. The main objective of this study was to investigate the cerebrospinal fluid (CSF) lipidomic signature of ALS patients by mass spectrometry to evaluate the diagnostic and predictive values of the profile. We showed that ALS patients (n = 40) displayed a highly significant specific CSF lipidomic signature compared to controls (n = 45). Phosphatidylcholine PC(36:4), higher in ALS patients (p = 0.0003) was the most discriminant molecule, and ceramides and glucosylceramides were also highly relevant. Analysis of targeted lipids in the brain cortex of ALS model mice confirmed the role of some discriminant lipids such as PC. We also obtained good models for predicting the variation of the ALSFRS-r score from the lipidome baseline, with an accuracy of 71% in an independent set of patients. Significant predictions of clinical evolution were found to be correlated to sphingomyelins and triglycerides with long-chain fatty acids. Our study, which shows extensive lipid remodelling in the CSF of ALS patients, provides a new metabolic signature of the disease and its evolution with good predictive performance.

Low IDL-B and high LDL-1 subfraction levels in serum of ALS patients.

INTRODUCTION: Converging evidence highlights that lipid metabolism plays a key role in ALS pathophysiology. Dyslipidemia has been described in ALS patients and may be protective but peripheral lipoprotein subclasses have never been studied. MATERIAL AND METHODS: We collected sera from 30 ALS patients and 30 gender and age-matched controls. We analyzed 11 distinct lipoprotein subclasses by linear polyacrylamide gel electrophoresis (Lipoprint, Quantimetrix Corporation, USA). We also measured lipoprotein (a), apolipoprotein B, and apolipoprotein E levels. RESULTS: ALS patients had significant higher total cholesterol, HDL-cholesterol, and LDL-cholesterol levels than controls (p<0.0001, p=0.0007, and p=0.0065, respectively). The LDL-1 subfraction concentration was higher (1.03±0.41 vs. 0.71±0.28mmol/L; p=0.0006) and the IDL-B subfraction lower (6.5±2% vs. 8.0±2%; p=0.001) in ALS patients than controls. DISCUSSION: Our preliminary work confirmed the association between ALS and dyslipidemia. The low IDL-B levels may explain the hepatic steatosis frequently reported in ALS. The high levels of the cholesterol-rich LDL-1 subfraction is consistent with previously reported hypercholesterolemia. CONCLUSION: This study describes, for the first time, the distribution of serum lipoproteins in ALS patients, with low IDL-B and high LDL-1 subfraction level.

Genetics of amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease characterized by upper and lower motor neuron damage in the bulbar and spinal territories. Although the pathophysiology of ALS is still unknown, the involvement of genetic factors is no longer a subject of debate. Familial ALS (fALS) accounts for 10-20% of cases. Since the identification of the SOD1 gene, more than 20 genes have been described, of which four can explain >50% of familial cases. This review is an update focused on major aspects of the field of ALS genetics concerning both causative and susceptibility factors.

A decrease in blood cholesterol after gastrostomy could impact survival in ALS.

Although the global benefits of gastrostomy have been proven in amyotrophic lateral sclerosis (ALS), the impact on biological parameters has not been explored yet. The aim of this preliminary work was to evaluate the modification of biological parameters in patients with ALS undergoing gastrostomy. We retrospectively collected clinical and biological data from 44 patients having undergone gastrostomy at three time points (T0, T1 and T2: before, at the time of and after gastrostomy). We examined the relationship between the biological parameters and disease progression. Variations of the concentrations of total cholesterol significantly differed before (T1-T0) vs those after gastrostomy (T2-T1; P=0.0044). The variations of total cholesterol and low-density lipoprotein cholesterol concentrations after gastrostomy were negatively associated with survival (P=0.0002). This study showed for the first time that patients with ALS fed quite exclusively by gastrostomy had decreased blood cholesterol after gastrostomy. We suggest that a restoration of normal lipid metabolism should be planned in patients with ALS.