Metabolite Repair Enzymes Control Metabolic Damage in Glycolysis.

Hundreds of metabolic enzymes work together smoothly in a cell. These enzymes are highly specific. Nevertheless, under physiological conditions, many perform side-reactions at low rates, producing potentially toxic side-products. An increasing number of metabolite repair enzymes are being discovered that serve to eliminate these noncanonical metabolites. Some of these enzymes are extraordinarily conserved, and their deficiency can lead to diseases in humans or embryonic lethality in mice, indicating their central role in cellular metabolism. We discuss how metabolite repair enzymes eliminate glycolytic side-products and prevent negative interference within and beyond this core metabolic pathway. Extrapolating from the number of metabolite repair enzymes involved in glycolysis, hundreds more likely remain to be discovered that protect a wide range of metabolic pathways.

Causes and consequences of impaired methionine synthase activity in acquired and inherited disorders of vitamin B12 metabolism.

Methyl-Cobalamin (Cbl) derives from dietary vitamin B12 and acts as a cofactor of methionine synthase (MS) in mammals. MS encoded by MTR catalyzes the remethylation of homocysteine to generate methionine and tetrahydrofolate, which fuel methionine and cytoplasmic folate cycles, respectively. Methionine is the precursor of S-adenosyl methionine (SAM), the universal methyl donor of transmethylation reactions. Impaired MS activity results from inadequate dietary intake or malabsorption of B12 and inborn errors of Cbl metabolism (IECM). The mechanisms at the origin of the high variability of clinical presentation of impaired MS activity are classically considered as the consequence of the disruption of the folate cycle and related synthesis of purines and pyrimidines and the decreased synthesis of endogenous methionine and SAM. For one decade, data on cellular and animal models of B12 deficiency and IECM have highlighted other key pathomechanisms, including altered interactome of MS with methionine synthase reductase, MMACHC, and MMADHC, endoplasmic reticulum stress, altered cell signaling, and genomic/epigenomic dysregulations. Decreased MS activity increases catalytic protein phosphatase 2A (PP2A) and produces imbalanced phosphorylation/methylation of nucleocytoplasmic RNA binding proteins, including ELAVL1/HuR protein, with subsequent nuclear sequestration of mRNAs and dramatic alteration of gene expression, including SIRT1. Decreased SAM and SIRT1 activity induce ER stress through impaired SIRT1-deacetylation of HSF1 and hypomethylation/hyperacetylation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α), which deactivate nuclear receptors and lead to impaired energy metabolism and neuroplasticity. The reversibility of these pathomechanisms by SIRT1 agonists opens promising perspectives in the treatment of IECM outcomes resistant to conventional supplementation therapies.

An evaluation of untargeted metabolomics methods to characterize inborn errors of metabolism.

Inborn errors of metabolism (IEMs) encompass a diverse group of disorders that can be difficult to classify due to heterogenous clinical, molecular, and biochemical manifestations. Untargeted metabolomics platforms have become a popular approach to analyze IEM patient samples because of their ability to detect many metabolites at once, accelerating discovery of novel biomarkers, and metabolic mechanisms of disease. However, there are concerns about the reproducibility of untargeted metabolomics research due to the absence of uniform reporting practices, data analyses, and experimental design guidelines. Therefore, we critically evaluated published untargeted metabolomic platforms used to characterize IEMs to summarize the strengths and areas for improvement of this technology as it progresses towards the clinical laboratory. A total of 96 distinct IEMs were collectively evaluated by the included studies. However, most of these IEMs were evaluated by a single untargeted metabolomic method, in a single study, with a limited cohort size (55/96, 57%). The goals of the included studies generally fell into two, often overlapping, categories: detecting known biomarkers from many biochemically distinct IEMs using a single platform, and detecting novel metabolites or metabolic pathways. There was notable diversity in the design of the untargeted metabolomic platforms. Importantly, the majority of studies reported adherence to quality metrics, including the use of quality control samples and internal standards in their experiments, as well as confirmation of at least some of their feature annotations with commercial reference standards. Future applications of untargeted metabolomics platforms to the study of IEMs should move beyond single-subject analyses, and evaluate reproducibility using a prospective, or validation cohort.

A review of fatty acid oxidation disorder mouse models.

Fatty acid oxidation disorders (FAODs) are a family of rare, genetic disorders that affect any part of the fatty acid oxidation pathway. Patients present with severe phenotypes, such as hypoketotic hypoglycemia, cardiomyopathy, and rhabdomyolysis, and currently manage these symptoms by the avoidance of fasting and maintaining a low-fat, high-carbohydrate diet. Because knowledge about FAODs is limited due to the small number of patients, rodent models have been crucial in learning more about these disorders, particularly in studying the molecular mechanisms involved in different phenotypes and in evaluating treatments for patients. The purpose of this review is to present the different FAOD mouse models and highlight the benefits and limitations of using these models. Specifically, we discuss the phenotypes of the available FAOD mouse models, the potential molecular causes of prominent FAOD phenotypes that have been studied using FAOD mouse models, and how FAOD mouse models have been used to evaluate treatments for patients.

Screening of 1.17 million newborns for inborn errors of metabolism using tandem mass spectrometry in Shanghai, China: A 19-year report.

BACKGROUND: Inborn errors of metabolism (IEMs) frequently result in progressive and irreversible clinical consequences if not be diagnosed or treated timely. The tandem mass spectrometry (MS/MS)-based newborn screening (NBS) facilitates early diagnosis and treatment of IEMs. The aim of this study was to determine the characteristics of IEMs and the successful deployment and application of MS/MS screening over a 19-year time period in Shanghai, China, to inform national NBS policy. METHODS: The amino acids and acylcarnitines in dried blood spots from 1,176,073 newborns were assessed for IEMs by MS/MS. The diagnosis of IEMs was made through a comprehensive consideration of clinical features, biochemical performance and genetic testing results. The levels of MS/MS testing parameters were compared between various IEM subtypes and genotypes. RESULTS: A total of 392 newborns were diagnosed with IEMs from January 2003 to June 2022. There were 196 newborns with amino acid disorders (50.00%, 1: 5910), 115 newborns with organic acid disorders (29.59%, 1: 10,139), and 81 newborns with fatty acid oxidation disorders (20.41%; 1:14,701). Phenylalanine hydroxylase deficiency, methylmalonic acidemia and primary carnitine deficiency were the three most common disorders. Some hotspot variations in eight IEM genes (PAH, SLC22A5, MMACHC, MMUT, MAT1A, MCCC2, ACADM, ACAD8), 35 novel variants and some genotype-biochemical phenotype associations were identified. CONCLUSIONS: A total of 28 types of IEMs were identified, with an overall incidence of 1: 3000 in Shanghai, China. Our study offered clinical guidance for the implementation of MS/MS-based NBS and genetic counseling for IEMs in this city.

Clinicogenetic characterization of cerebrotendinous xanthomatosis in Brazil.

There are few cerebrotendineous xanthomatosis (CTX) case series and observational studies including a significant number of Latin American patients. We describe a multicenter Brazilian cohort of patients with CTX highlighting their clinical phenotype, recurrent variants and assessing possible genotype-phenotype correlations. We analyzed data from all patients with clinical and molecular or biochemical diagnosis of CTX regularly followed at six genetics reference centers in Brazil between March 2020 and August 2023. We evaluated 38 CTX patients from 26 families, originating from 4 different geographical regions in Brazil. Genetic analysis identified 13 variants in the CYP27A1 gene within our population, including 3 variants that had not been previously described. The most frequent initial symptom of CTX in Brazil was cataract (27%), followed by xanthomas (24%), chronic diarrhea (13.5%), and developmental delay (13.5%). We observed that the median age at loss of ambulation correlates with the age of onset of neurological symptoms, with an average interval of 10 years (interquartile range 6.9 to 11 years). This study represents the largest CTX case series ever reported in South America. We describe phenotypic characteristics and report three new pathogenic or likely pathogenic variants.

Severe Acute Motor Exacerbations (SAME) across Metabolic, Developmental and Genetic Disorders.

Acute presentation of severe motor disorders is a diagnostic and management challenge. We define severe acute motor exacerbations (SAME) as acute/subacute motor symptoms that persist for hours-to-days with a severity that compromise vital signs (temperature, breath, and heart rate) and bulbar function (swallowing/dysphagia). Phenomenology includes dystonia, choreoathetosis, combined movement disorders, weakness, and hemiplegic attacks. SAME can develop in diverse diseases and can be preceded by triggers or catabolic states. Recent descriptions of SAME in complex neurodevelopmental and epileptic encephalopathies have broadened appreciation of this presentation beyond inborn errors of metabolism. A high degree of clinical suspicion is required to identify appropriately targeted investigations and management. We conducted a comprehensive literature analysis of etiologies. Reported triggers are described and classified as per pathophysiological mechanism. A video of six cases displaying multiple SAME with diverse outcomes is provided. We identified 50 different conditions that manifest SAME, some associated with developmental regression. Etiologies include disorders of metabolism: energy substrate, amino acids, complex molecules, vitamins/cofactors, minerals, and neurotransmitters/synaptic vesicle cycling. Non-metabolic neurodegenerative and genetic disorders that present with movement disorders and epilepsy can additionally manifest SAME. A limited number of triggers are grouped here, together with an approach to investigations and general management strategies. Several neurogenetic and neurometabolic disorders manifest SAME. Identifying triggers can help in certain cases narrow the differential diagnosis and guide the expeditious application of targeted therapies to minimize adverse developmental and neurological consequences. This process may inform pathogenesis and eventually improve our understanding of the mechanisms that lead to the development of SAME. © 2024 International Parkinson and Movement Disorder Society.

Metabolic Determinants of Cerebellar Circuit Formation and Maintenance.

Cells configure their metabolism in a synchronized and timely manner to meet their energy demands throughout development and adulthood. Transitions of developmental stages are coupled to metabolic shifts, such that glycolysis is highly active during cell proliferation, whereas oxidative phosphorylation prevails in postmitotic states. In the cerebellum, metabolic transitions are remarkable given its protracted developmental timelines. Such distinctive feature, along with its high neuronal density and metabolic demands, make the cerebellum highly vulnerable to metabolic insults. Despite the expansion of metabolomic approaches to uncover biological mechanisms, little is known about the role of metabolism on cerebellar development and maintenance. To illuminate the intricate connections between metabolism, physiology, and cerebellar disorders, we examined here the impact of metabolism on cerebellar growth, maturation, and adulthood through the lens of inborn errors of metabolism.

When rare meets common: Treatable genetic diseases are enriched in the general psychiatric population.

Mental illnesses are one of the biggest contributors to the global disease burden. Despite the increased recognition, diagnosis and ongoing research of mental health disorders, the etiology and underlying molecular mechanisms of these disorders are yet to be fully elucidated. Moreover, despite many treatment options available, a large subset of the psychiatric patient population is nonresponsive to standard medications and therapies. There has not been a comprehensive study to date examining the burden and impact of treatable genetic disorders (TGDs) that can present with neuropsychiatric features in psychiatric patient populations. In this study, we test the hypothesis that TGDs that present with psychiatric symptoms are more prevalent within psychiatric patient populations compared to the general population by performing targeted next-generation sequencing of 129 genes associated with 108 TGDs in a cohort of 2301 psychiatric patients. In total, 48 putative affected and 180 putative carriers for TGDs were identified, with known or likely pathogenic variants in 79 genes. Despite screening for only 108 genetic disorders, this study showed a two-fold (2.09%) enrichment for genetic disorders within the psychiatric population relative to the estimated 1% cumulative prevalence of all single gene disorders globally. This strongly suggests that the prevalence of these, and most likely all, genetic diseases is greatly underestimated in psychiatric populations. Increasing awareness and ensuring accurate diagnosis of TGDs will open new avenues to targeted treatment for a subset of psychiatric patients.

Biochemical signatures of disease severity in multiple sulfatase deficiency.

Sulfatases catalyze essential cellular reactions, including degradation of glycosaminoglycans (GAGs). All sulfatases are post-translationally activated by the formylglycine generating enzyme (FGE) which is deficient in multiple sulfatase deficiency (MSD), a neurodegenerative lysosomal storage disease. Historically, patients were presumed to be deficient of all sulfatase activities; however, a more nuanced relationship is emerging. Each sulfatase may differ in their degree of post-translational modification by FGE, which may influence the phenotypic spectrum of MSD. Here, we evaluate if residual sulfatase activity and accumulating GAG patterns distinguish cases from controls and stratify clinical severity groups in MSD. We quantify sulfatase activities and GAG accumulation using three complementary methods in MSD participants. Sulfatases differed greatly in their tolerance of reduction in FGE-mediated activation. Enzymes that degrade heparan sulfate (HS) demonstrated lower residual activities than those that act on other GAGs. Similarly, HS-derived urinary GAG subspecies preferentially accumulated, distinguished cases from controls, and correlated with disease severity. Accumulation patterns of specific sulfatase substrates in MSD provide fundamental insights into sulfatase regulation and will serve as much-needed biomakers for upcoming clinical trials. This work highlights that biomarker investigation of an ultra-rare disease can simultaneously inform our understanding of fundamental biology and advance clinical trial readiness efforts.

Targeted ultra performance liquid chromatography tandem mass spectrometry procedures for the diagnosis of inborn errors of metabolism: validation through ERNDIM external quality assessment schemes.

OBJECTIVES: Early diagnosis of inborn errors of metabolism (IEM) is crucial to ensure early detection of conditions which are treatable. This study reports on targeted metabolomic procedures for the diagnosis of IEM of amino acids, acylcarnitines, creatine/guanidinoacetate, purines/pyrimidines and oligosaccharides, and describes its validation through external quality assessment schemes (EQA). METHODS: Analysis was performed on a Waters ACQUITY UPLC H-class system coupled to a Waters Xevo triple-quadrupole (TQD) mass spectrometer, operating in both positive and negative electrospray ionization mode. Chromatographic separation was performed on a CORTECS C18 column (2.1 × 150, 1.6 µm). Data were collected by multiple reaction monitoring. RESULTS: The internal and EQA results were generally adequate, with a few exceptions. We calculated the relative measurement error (RME) and only a few metabolites displayed a RME higher than 30 % (asparagine and some acylcarnitine species). For oligosaccharides, semi-quantitative analysis of an educational panel clearly identified the 8 different diseases included. CONCLUSIONS: Overall, we have validated our analytical system through an external quality control assessment. This validation will contribute to harmonization between laboratories, thus improving identification and management of patients with IEM.

Current status and future directions of liver transplantation for metabolic liver disease in children.

Orthotopic liver transplantation (OLT) in the care of children with inborn errors of metabolism (IEM) is well established and represent the second most common indication for pediatric liver transplantation in most centers worldwide, behind biliary atresia. OLT offers cure of disease when a metabolic defect is confined to the liver, but may still be transformative on a patient's quality of life reducing the chance of metabolic crises causing neurological damage in children be with extrahepatic involvement and no "functional cure." Outcomes post-OLT for inborn errors of metabolism are generally excellent. However, this benefit must be balanced with consideration of a composite risk of morbidity, and commitment to a lifetime of post-transplant chronic disease management. An increasing number of transplant referrals for children with IEM has contributed to strain on graft access in many parts of the world. Pragmatic evaluation of IEM referrals is essential, particularly pertinent in cases where progression of extra-hepatic disease is anticipated, with long-term outcome expected to be poor. Decision to proceed with liver transplantation is highly individualized based on the child's dynamic risk-benefit profile, their family unit, and their treating multidisciplinary team. Also to be considered is the chance of future treatments, such as gene therapies, emerging in the medium term.

Case presentation: a severe case of cobalamin c deficiency presenting with nephrotic syndrome, malignant hypertension and hemolytic anemia.

BACKGROUND: The etiology of nephrotic syndrome can vary, with underlying metabolic diseases being a potential factor. Cobalamin C (cblC) defect is an autosomal recessive inborn error of metabolism caused by mutations in the MMACHC gene, resulting in impaired vitamin B12 processing. While cblC defect typically manifests with hematological and neurological symptoms, renal involvement is increasingly recognized but remains rare. CASE PRESENTATION: We describe a 7-month-old male patient presenting with fatigue and edema. His first laboratory findings showed anemia, thrombocytopenia, hypoalbuminemia and proteinuria and further examinations reveals hemolysis in peripheric blood smear. During his follow up respiratory distress due to pleural effusion in the right hemithorax was noticed. And fluid leakage to the third spaces supported nephrotic syndrome diagnosis. The patient's condition deteriorated, leading to intensive care admission due to, hypertensive crisis, and respiratory distress. High total plasma homocysteine and low methionine levels raised suspicion of cobalamin metabolism disorders. Genetic testing confirmed biallelic MMACHC gene mutations, establishing the diagnosis of cblC defect. Treatment with hydroxycobalamin, folic acid, and betaine led to remarkable clinical improvement. DISCUSSION/CONCLUSION: This case underscores the significance of recognizing metabolic disorders like cblC defect in atypical presentations of nephrotic syndrome. Early diagnosis and comprehensive management are vital to prevent irreversible renal damage. While cblC defects are more commonly associated with atypical hemolytic uremic syndrome, this case highlights the importance of considering cobalamin defects in the differential diagnosis of nephrotic syndrome, especially when associated with accompanying findings such as hemolysis. Our case, which has one of the highest homocysteine levels reported in the literature, emphasizes this situation again.

Retrospective analysis of reference intervals for dried blood spot based ms/ms newborn screening programs in Chinese preterm neonates: a nationwide study.

OBJECTIVES: Although recent discoveries regarding the biomarkers of newborn screening (NBS) programs by tandem mass spectrometry (MS/MS) highlight the critical need to establish reference intervals (RIs) specifically for preterm infants, no such RIs has been formally published yet. This study addressed the gap by offering a comprehensive set of reference intervals (RIs) for preterm neonates, and illustrating the dynamic changes of each biomarker with age. DESIGN AND METHODS: The NBS data of 199,693 preterm newborns (< 37 weeks of gestation) who met the inclusion and exclusion criteria from the NNSCP database were included in study analysis. The birth weight stratified dynamic trend of each biomarker were captured by their concentrations over age. Reference partitions were determined by the method of Harris and Boyd. RIs, corresponding to the 2.5th and 97.5th percentiles, as well as the 0.5th, 25th, 50th, 75th and 99.5th percentiles were calculated using a non-parametric rank approach. RESULTS: Increasing birth weight is associated with an elevation in the levels of arginine, citrulline, glycine, leucine and isobarics, methionine, ornithine, phenylalanine, and valine, whereas the levels of alanine, proline and tyrosine decrease. Additionally, two short-chain acylcarnitines (butyrylcarnitine + isobutyrylcarnitine and isovalerylcarnitine + methylbutyrylcarnitine) and a median-chain acylcarnitine (octenoylcarnitine) decrease, while four long-chain acylcarnitines (tetradecanoylcarnitine, palmitoylcarnitine, palmitoleylcarnitine and oleoylcarnitine) increase with increasing birth weight. Age impacts the levels of all MS/MS NBS biomarkers, while sex only affects the level of malonylcarnitine + 3-hydroxybutyrylcarnitine (C3-DC + C4-OH) in very low birth weight preterm neonates. CONCLUSION: The current study developed reference intervals (RIs) specific to birth weight, age, and/or sex for 35 MS/MS biomarkers, which can help in the timely evaluation of the health and disease of preterm neonates.

Seizure Characteristics and EEG Features in Intoxication Type and Energy Deficiency Neurometabolic Disorders in the Pediatric Intensive Care Unit: Single-Center Experience Over 10 Years.

BACKGROUND: Acute metabolic crises in inborn errors of metabolism (such as urea cycle disorders, organic acidemia, maple syrup urine disease, and mitochondrial disorders) are neurological emergencies requiring management in the pediatric intensive care unit (PICU). There is a paucity of data pertaining to electroencephalograms (EEG) characteristics in this cohort. We hypothesized that the incidence of background abnormalities and seizures in this cohort would be high. Neuromonitoring data from our center's PICU over 10 years are presented in this article. METHODS: Data were collected by retrospective chart review for patients with the aforementioned disorders who were admitted to the PICU at our institution because of metabolic/neurologic symptoms from 2008 to 2018. Descriptive statistics (χ2 test or Fisher's exact test) were used to study the association between EEG parameters and outcomes. RESULTS: Our cohort included 40 unique patients (8 with urea cycle disorder, 7 with organic acidemia, 3 with maple syrup urine disease, and 22 with mitochondrial disease) with 153 admissions. Presenting symptoms included altered mentation (36%), seizures (41%), focal weakness (5%), and emesis (28%). Continuous EEG was ordered in 34% (n = 52) of admissions. Twenty-three admissions were complicated by seizures, including eight manifesting as status epilepticus (seven nonconvulsive and one convulsive). Asymmetry and focal slowing on EEG were associated with seizures. Moderate background slowing or worse was noted in 75% of EEGs. Among those patients monitored on EEG, 4 (8%) died, 3 (6%) experienced a worsening of their Pediatric Cerebral Performance Category (PCPC) score as compared to admission, and 44 (86%) had no change (or improvement) in their PCPC score during admission. CONCLUSIONS: This study shows a high incidence of clinical and subclinical seizures during metabolic crisis in patients with inborn errors of metabolism. EEG background features were associated with risk of seizures as well as discharge outcomes. This is the largest study to date to investigate EEG features and risk of seizures in patients with neurometabolic disorders admitted to the PICU. These data may be used to inform neuromonitoring protocols to improve mortality and morbidity in inborn errors of metabolism.

Exploratory Untargeted Metabolomics of Dried Blood Spot Samples from Newborns with Maple Syrup Urine Disease.

Currently, tandem mass spectrometry-based newborn screening (NBS), which examines targeted biomarkers, is the first approach used for the early detection of maple syrup urine disease (MSUD) in newborns, followed by confirmatory genetic mutation tests. However, these diagnostic approaches have limitations, demanding the development of additional tools for the diagnosis/screening of MUSD. Recently, untargeted metabolomics has been used to explore metabolic profiling and discover the potential biomarkers/pathways of inherited metabolic diseases. Thus, we aimed to discover a distinctive metabolic profile and biomarkers/pathways for MSUD newborns using untargeted metabolomics. Herein, untargeted metabolomics was used to analyze dried blood spot (DBS) samples from 22 MSUD and 22 healthy control newborns. Our data identified 210 altered endogenous metabolites in MSUD newborns and new potential MSUD biomarkers, particularly L-alloisoleucine, methionine, and lysoPI. In addition, the most impacted pathways in MSUD newborns were the ascorbate and aldarate pathways and pentose and glucuronate interconversions, suggesting that oxidative and detoxification events may occur in early life. Our approach leads to the identification of new potential biomarkers/pathways that could be used for the early diagnosis/screening of MSUD newborns but require further validation studies. Our untargeted metabolomics findings have undoubtedly added new insights to our understanding of the pathogenicity of MSUD, which helps us select the appropriate early treatments for better health outcomes.

Chemical individuality in T cells: A Garrodian view of immunometabolism.

Metabolically quiescent T cells circulate throughout the body in search of antigen. Following engagement of their cognate receptors, T cells undergo metabolic reprogramming to support their activation, differentiation, and ultimately function. In the spirit of Sir Archibald Garrod, this metabolic reprogramming actually imparts a chemical individuality which confers advantage, while in others confers vulnerability, depending upon the milieu. Studying T cell immunometabolism in the context of inborn errors of metabolism allows one to define essential pathways of intermediary metabolism as well metabolic vulnerabilities and plasticity. Inborn errors of metabolism, a class of diseases first named by Garrod, have a long history of being informative for common physiologic and pathologic processes. This endeavor may be accomplished through the study of patients, animal models, and in vitro models of inborn errors of metabolism. In this review, the basics of intermediary metabolism and core metabolic pathways will be discussed, along with their relationship to T cell immunometabolism. Due to their pleiotropic nature, the reader will be specifically directed toward various inborn errors of metabolism which may be helpful for answering important questions about the role of metabolism in T cells.

Closing the gap: An urgent need for newborn screening of organic acid disorders in developing countries.

Organic acid disorders are rare inherited metabolic disorders of key metabolic pathways. For the identification of specific organic acids, investigation of urinary metabolites and genetic testing are required through newborn screening programmes. Delayed diagnosis leads to complications, such as cardiac attacks, respiratory problems, neuro-developmental disorders, intellectual disability, and even premature death. The burden of such inherited disorders is quite high in developing countries of South Asia due to high rate of consanguinity in the region. Unfortunately, such disorders are left untreated due to the lack of screening facilities in such countries. The current narrative review was planned to highlight the urgent need for closing this gap and implementing effective newborn screening programmes for organic acid disorders in developing countries. The implementation of effective programmes is crucial for reducing morbidity and mortality, and for improving the quality of life for the affected children and of their families, thus promoting global health equity.

Establishment of Age Specific Reference Interval for Aminoacids and Acylcarnitine in Dried Blood Spot by Tandem Mass Spectrometry.

The Extended Screening for Inborn Errors of Metabolism is done for aminoacidopathies, fatty acid oxidation disorders and organic acid disorders. In a single dried blood spot, the tandem mass spectrometry is capable of measuring multiple analytes like amino acids, acylcarnitines, nucleosides, succinylacetone and lysophosphatidylcholines. This study was proposed to establish age specific reference internal for aminoacids and acylcartinitine in dried blood spot by tandem mass spectrometry. A total of 480 apparently healthy children were enrolled for the study and sub classified into four groups as follows: Group A: 0-1 month, Group B: 1 month-1 year, Group C: 1-5 year and Group D: 5-12 years each having 120 participants. Sample size were calculated as per CLSI approved guidelines. Tables 1 and 2 presents the age-specific percentile distribution of aminoacids and acylcarnitines established from healthy subjects as per rank-based method recommended by the IFCC and CLSI. Tables 3, 4 and 5 presents the cut-off values of primary and secondary marker/ratios for screening of aminoacidopathies, fatty acid oxidation disorders and organic acid disorders respectively. As a general principle, the interpretation of extended newborn screening results should be based on age specific cut-off established by the laboratory for primary analyte concentration and secondary analyte concentration/ ratios. This study was useful in establishing age specific cut-off values for various amino acids and acylcarnitines in South Indian population. [Table: see text] [Table: see text] [Table: see text] [Table: see text] [Table: see text].

Evaluation of biochemical profile and oxidative damage to lipids and proteins in patients with lysosomal acid lipase deficiency.

Lysosomal acid lipase deficiency (LALD) is an inborn error of metabolism that lacks satisfactory treatment, which leads to the development of severe hepatic and cardiac complications and may even lead to death. In this sense, knowledge of the mechanisms involved in the pathophysiology of this disorder becomes essential to allow the search for new therapeutic strategies. There are no studies in the literature investigating the role of reactive species and inflammatory processes in the pathophysiology of this disorder. Therefore, the aim of this work was to investigate parameters of oxidative and inflammatory stress in LALD patients. In this work, we obtained results that demonstrate that LALD patients are susceptible to oxidative stress caused by an increase in the production of free radicals, observed by the increase of 2-7-dihydrodichlorofluorescein. The decrease in sulfhydryl content reflects oxidative damage to proteins, as well as a decrease in antioxidant defenses. Likewise, the increase in urinary levels of di-tyrosine observed also demonstrates oxidative damage to proteins. Furthermore, the determination of chitotriosidase activity in the plasma of patients with LALD was significantly higher, suggesting a pro-inflammatory state. An increase in plasma oxysterol levels was observed in patients with LALD, indicating an important relationship between this disease and cholesterol metabolism and oxidative stress. Also, we observed in LALD patients increased levels of nitrate production. The positive correlation found between oxysterol levels and activity of chitotriosidase in these patients indicates a possible link between the production of reactive species and inflammation. In addition, an increase in lipid profile biomarkers such as total and low-density lipoprotein cholesterol were demonstrated in the patients, which reinforces the involvement of cholesterol metabolism. Thus, we can assume that, in LALD, oxidative and nitrosative damage, in addition to inflammatory process, play an important role in its evolution and future clinical manifestations. In this way, we can suggest that the study of the potential benefit of the use of antioxidant and anti-inflammatory substances as an adjuvant tool in the treatment will be important, which should be associated with the already recommended therapy.