Acylcarnitine Analysis Research Articles

Serum concentrations of lipids, ketones and acylcarnitines during the postprandial and fasting state: the Postprandial Metabolism (PoMet) study in healthy young adults.

To improve the interpretation and utilisation of blood lipids, ketones and acylcarnitine concentrations as biomarkers in clinical assessments, more information is needed on their dynamic alterations in response to dietary intake and fasting. The aim of this intervention study was to characterise the changes in serum lipid, ketone and acylcarnitine concentrations 24 h after a standardised breakfast meal. Thirty-four healthy subjects (eighteen males and sixteen females) aged 20-30 years were served a breakfast meal (∼500 kcal, 36 E% fat, 46 E% carbohydrates, 16 E% protein, 2E% fibre), after which they consumed only water for 24 h. Blood samples were drawn before and at thirteen standardised timepoints after the meal. Metabolite concentrations were plotted as a function of time since the completion of the breakfast meal. Results demonstrated that concentrations of HDL-cholesterol and LDL-cholesterol decreased until ∼2 h (-4 % for both), while TAG concentrations peaked at 3 h (+27 %). Acetoacetate and β-hydroxybutyrate were highest 24 h after the meal (+433 and +633 %, respectively). Acetylcarnitine, butyrylcarnitine, hexanoylcarnitine, octanoylcarnitine, decanoylcarnitine and dodecanoylcarnitine reached the lowest values at 60 min (decreases ranging from -47 to -70 %), before increasing and peaking at 24 h after the meal (increases ranging from +86 to +120 %). Our findings suggest that distinguishing between fasting and non-fasting blood samples falls short of capturing the dynamics in lipid, ketone, carnitine and acylcarnitine concentrations. To enhance the utility of serum acylcarnitine analyses, we strongly recommend accounting for the specific time since the last meal at the time of blood sampling.

Recurrent rhabdomyolysis caused by palmitoyltransferase II (CPT-2) deficiency but complete normal acylcarnitine profile: A patient presentation and review of the literature

Recurrent rhabdomyolysis, marked by skeletal muscle breakdown, can stem from various causes, including genetic disorders. We detail a patient of a 22-year-old male with carnitine palmitoyltransferase II (CPT-2) deficiency manifesting recurrent rhabdomyolysis despite normal acylcarnitine profiles. Whole-genome sequencing identified two CPT2 gene variants: c.338C > T and c.482G > A, confirming the diagnosis. We conducted a case report and a comprehensive literature review encompassing 262 articles related to CPT-2 deficiency available on PubMed. The review detailed 245 cases across various forms, including lethal neonatal, severe infantile hepatocardiomuscular, and myopathic forms. The study highlighted the variability and complexity of CPT-2 deficiency phenotypes, emphasizing correlations between variants and phenotypes as well as gender distribution. Although the CPT-2 deficiency genotype does not entirely predict phenotype severity, it remains informative for most patients, assisting in assessing the severity linked to each genetic variant. The results of our study offer crucial insights into evaluating the severity associated with individual genetic variants. Notably, our patient displayed normal acylcarnitine profiles between illness episodes, indicating possible profile abnormalities only during active disease states.We propose the collection of additional blood samples for acylcarnitine analysis during episodes of rhabdomyolysis without delay in all patients presenting with rhabdomyolysis of unknown cause as a crucial diagnostic strategy. This approach may unveil unexpected underlying diseases, enabling early and accurate diagnoses.

SCOT Deficiency Mimicking Sepsis: An Unusual Cause of Increased Anion Gap Metabolic Acidosis

Introduction: Succinyl-CoA:3-oxoacid CoA transferase (SCOT, EC 2.8.3.5) deficiency is a rare autosomal recessive inborn error of metabolism (IEM). We report here an infant admitted to intensive care unit with the diagnosis of sepsis. Case Presentation: A five-month-old female patient was admitted to the intensive care unit with lethargy and respiratory distress. She had severe high anion gap metabolic acidosis. The IEM was screened by plasma amino acid analysis, showing no abnormalities, and by acylcarnitine analysis, showing low-normal levels of free carnitine. Urine organic acid analysis revealed massive ketonuria and elevated levels of dicarboxylic acids. Fatty acid oxidation disorder-targeted gene panel revealed a homozygous splice site variant (c.78+1_78+6 del) in the OXCT1 gene. Discussion and Conclusion: SCOT deficiency should be considered when massive ketosis is detected in increased anion gap metabolic acidosis with sepsis-like manifestation. Supportive therapy should be initiated quickly to prevent irreversible neurological damage.

Development of a second-tier method for C4, C5 and C2 acylcarnitine analysis in plasma

IntroductionAcylcarnitines are typically analyzed using either a flow injection analysis (FIA) method or liquid chromatography-mass spectrometry (LC-MS/MS) methods. The FIA method is a fast, efficient method, however it does not have the capability to separate compounds with the same molecular weight. These isobaric interferences can be removed by chromatographic separation with LC-MS/MS. In this study, we aimed to develop and optimize a qualitative LC-MS/MS method to separate the isobaric interferences for two-, four- and five-carbon acylcarnitines. MethodsThe samples were first prepared by acylcarnitine derivatization with butanolic HCl. The developed LC-MS/MS method is a combination of isocratic and gradient elution used to separate acylcarnitines. Multiple reaction monitoring was used for determination of precursor and product ions for each acylcarnitine species as well as known interferences used in our study. We used this method to analyze quality assurance and patient samples with elevated two-, four- and five-carbon acylcarnitines. ResultsButyryl- and isobutyrylcarnitines as well as valeryl- and isovalerylcarnitines were successfully separated using the developed method. This method was able also to separate and distinguish acetylcarnitine from glutamate interference that has been causing overestimation of acetylcarnitine. In patients, the dominant five-carbon acylcarnitine was found to be isovalerylcarnitine. We confirmed that the majority of analyzed patient samples had additional carnitine adducts present but not valerylcarnitine. Butyryl- and isobutyrylcarnitines, in variable ratios, were present in every patient sample. ConclusionWe developed a qualitative LC-MS/MS method for butyl-ester derivatized acylcarnitines, which can be used as a second-tier method for diagnosis and monitoring of various inborn errors of metabolism in our hospital network.

Experience with carnitine palmitoyltransferase II deficiency: diagnostic challenges in the myopathic form.

Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal recessive disorder of long-chain fatty acid oxidation. Three clinical phenotypes, lethal neonatal form, severe infantile hepatocardiomuscular form, and myopathic form, have been described in CPT II deficiency. The myopathic form is usually mild and can manifest from infancy to adulthood, characterised by recurrent rhabdomyolysis episodes. The study aimed to investigate the clinical features, biochemical, histopathological, and genetic findings of 13 patients diagnosed with the myopathic form ofCPT II deficiency at Ege University Hospital. A retrospective study was conducted with 13 patients with the myopathic form of CPT II deficiency. Our study considered demographic data, triggers of recurrent rhabdomyolysis attacks, biochemical metabolic screening, and molecular analysis. Ten patients were examined for rhabdomyolysis ofunknown causes. Two patients were diagnosed during family screening, and one was diagnosed during investigations due to increased liver function tests. Acylcarnitine profiles were normal in five patients during rhabdomyolysis. Genetic studies have identified a c.338C>T (p.Ser113Leu) variant homozygous in 10 patients. One patient showed a novel frameshift variant compound heterozygous with c.338C>T (p.Ser113Leu). Plasma acylcarnitine analysis should be preferred as it is superior to DBS acylcarnitine analysis in diagnosing CPT II deficiency. Even if plasma acylcarnitine analysis is impossible, CPT2 gene analysis should be performed. Our study emphasizes that CPT II deficiency should be considered in the differential diagnosis of recurrent rhabdomyolysis, even if typical acylcarnitine elevation does not accompany it.

New Acylcarnitine Ratio as a Reliable Indicator of Long-Chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency.

Long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) and mitochondrial trifunctional protein (MTP) deficiencies are rare fatal disorders of fatty acid β-oxidation with no apparent genotype-phenotype correlation. The measurement of acylcarnitines by MS/MS is a current diagnostic workup in these disorders. Nevertheless, false-positive and false-negative results have been reported, highlighting a necessity for more sensitive and specific biomarkers. This study included 54 patients with LCHAD/MTP deficiency that has been confirmed by biochemical and molecular methods. The analysis of acylcarnitines in dried blood spots was performed using ESI-MS/MS. The established "HADHA ratio" = (C16OH + C18OH + C18:1OH)/C0 was significantly elevated in all 54 affected individuals in comparison to the control group. Apart from 54 LCHAD deficiency patients, the "HADHA ratio" was calculated in 19 patients with very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. As VLCAD-deficient patients did not show increased "HADHA ratio", the results emphasized the high specificity of this new ratio. Therefore, the "HADHA ratio" was shown to be instrumental in improving the overall performance of MS/MS-based analysis of acylcarnitine levels in the diagnostics of LCHAD/MTP deficiencies. The ratio was demonstrated to increase the sensitivity and specificity of this method and reduce the chances of false-negative results.

Streamlined determination of 3-O-methyldopa in dried blood spots: Prospective screening for aromatic l-amino-acid decarboxylase deficiency

BackgroundAromatic L-amino-acid decarboxylase (AADC) deficiency diagnosis is often delayed by low disease awareness and specific laboratory examinations. We demonstrated that an elevated concentration of L-dopa metabolite 3-O-methyldopa (3-OMD) in dried blood spots could be integrated into a newborn screening program to detect AADC deficiency. MethodsDBS samples for amino acid and acylcarnitine analysis using NeoBase™2 reagents were also analyzed for the 3-OMD concentration using 13C6-phenylalanine as an internal standard. For samples exceeding the pre-defined cutoffs, an additional spot was punched from the original filter paper for second-tier 3-OMD measurement by high performance liquid chromatography (HPLC)-MS/MS assay. Newborns with a 3-OMD concentration exceeding 500 ng/mL were referred for confirmatory testing. ResultsFrom Feb. 2020 to Dec. 2022, 157,371 newborns were screened for AADC deficiency. Eight newborns exhibited an elevated 3-OMD concentration (839–5170 ng/mL). Among them, six newborns were confirmed to carry two pathogenic DDC variants, indicating an incidence of AADC deficiency of ∼1:26,000 (95% confidence interval: 1 in 12,021 to 1 in 57,228). During the follow-up period, all six patients developed typical symptoms of AADC deficiency. ConclusionThe screening for 3-OMD, a target for AADC deficiency, could be easily integrated into the existing newborn screening programs and facilitate the future application for early diagnosis and effective treatment.

High-Throughput Analysis of Underivatized Amino Acids and Acylcarnitines in Infant Serum: A Micromethod Based on Stable Isotope Dilution Targeted HILIC-ESI-MS/MS.

Amino acids and acylcarnitines are important biomarkers of the body's energy state and can be used as diagnostic markers of certain inborn errors of metabolism. Few multianalyte methods for high-throughput analysis in serum exist for these compounds, but micromethods suitable for use in young children and infants are lacking. Therefore, we developed a quantitative high-throughput multianalyte hydrophilic interaction liquid chromatography-tandem mass spectrometry method preceded by a derivatization-free sample preparation using minimum amounts of serum (25 μL). Isotopically labeled standards were utilized for quantification. Forty amino acids and amino acid derivatives and 22 acylcarnitines were detected by applying a multiple reaction monitoring mode within a 20 min run. The method was comprehensively validated, comprising linearity, accuracy, (intraday/interday) precision, and quantitation limits, of which the latter ranged from 0.25 to 50 nM for acylcarnitines and from 0.005 to 1 μM for amino acids and their derivatives. Application of the method to 145 serum samples of three- to four-month-old healthy infants showed excellent reproducibility for multiday analyses and enabled simultaneous amino acid and acylcarnitine profiling in this age group.

Rapid and efficient LC-MS/MS diagnosis of inherited metabolic disorders: a semi-automated workflow for analysis of organic acids, acylglycines, and acylcarnitines in urine.

The analysis of organic acids in urine is an important part of the diagnosis of inherited metabolic disorders (IMDs), for which gas chromatography coupled with mass spectrometry is still predominantly used. Ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for urinary organic acids, acylcarnitines and acylglycines was developed and validated. Sample preparation consists only of dilution and the addition of internal standards. Raw data processing is quick and easy using selective scheduled multiple reaction monitoring mode. A robust standardised value calculation as a data transformation together with advanced automatic visualisation tools are applied for easy evaluation of complex data. The developed method covers 146 biomarkers consisting of organic acids (n=99), acylglycines (n=15) and acylcarnitines (n=32) including all clinically important isomeric compounds present. Linearity with r2>0.98 for 118 analytes, inter-day accuracy between 80 and 120 % and imprecision under 15 % for 120 analytes were achieved. Over 2 years, more than 800 urine samples from children tested for IMDs were analysed. The workflow was evaluated on 93 patient samples and ERNDIM External Quality Assurance samples involving a total of 34 different IMDs. The established LC-MS/MS workflow offers a comprehensive analysis of a wide range of organic acids, acylcarnitines and acylglycines in urine to perform effective, rapid and sensitive semi-automated diagnosis of more than 80 IMDs.

2-Methylglutaconic acid as a biomarker in routine urine organic acids leading to the diagnosis of glutaric acidemia type I in a low excretor

GA1 (OMIM# 231670) is an organic aciduria caused by defective Glutaryl-CoA dehydrogenase (GCDH), encoded by GCDH. Early detection of GA1 is crucial to prevent patients from developing acute encephalopathic crisis and subsequent neurologic sequelae. Diagnosis of GA1 relies on elevated glutarylcarnitine (C5DC) in plasma acylcarnitine analysis and hyperexcretion of glutaric acid (GA) and 3-hydroxyglutaric acid (3HG) in urine organic acid (UOA) analysis. Low excretors (LE), however, exhibit subtly elevated or even normal plasma C5DC and urinary GA levels, leading to screening and diagnostic challenges. The measurement of 3HG in UOA is thus often used as the 1st tier test for GA1. We described a case of LE detected via newborn screen with normal excretion of GA, absent of 3HG and increased 2-methylglutaconic acid (2MGA), which was detected at 3mg/g creatinine (reference interval<1mg/g creatinine) without appreciable ketones. We retrospectively examined UOA of 8 other GA1 patients and the 2MGA level ranged from 2.5 to 27.39mg/g creatinine, which is significantly higher than normal controls (0.05-1.61mg/g creatinine). Although the underlying mechanism of 2MGA formation in GA1 is unclear, our study suggests 2MGA is a biomarker for GA1 and should be monitored by routine UOA to evaluate its diagnostic and prognostic value.

Mass spectrometry for screening of metabolic disorders

Background/aim Inborn errors of metabolism (IEM) are a group of congenital disorders that result from deficiency of enzymes or transporters involved in different metabolic pathways in the human body. The most severe form of these disorders appears early in the neonatal period; however, most types of IEMs are responsive to treatment if started early enough before the appearance of serious complications. The introduction of mass spectrometric techniques for analysis of metabolites accumulated in IEM facilitates the early diagnosis through enabling analysis of a large number of samples in a short period of time using small sample sizes suitable for patients in the neonatal period. The aim of this study was to find out the prevalence of amino acids, fatty acids, and organic acids disorders, using mass spectrometry among Egyptian children with metabolic disorders who were referred to the Biochemical Genetics Lab, Human Genetics, and Genome Research Institute, National Research Centre, Cairo, Egypt, over a period of 9 years. Patients and methods The present study enrolled 9245 children who visited Biochemical Genetics Department, Human Genetics, and Genome Research Institute, National Research Centre Cairo, Egypt, during the period from 2013 to 2021. All children were subjected to quantitative analysis of amino acids and acylcarnitine profiles in blood, using liquid chromatography/tandem mass spectrometry, whereas qualitative analysis of organic acids was done in urine by gas chromatography/mass spectrometry. Results Of 9245 suspected patients, 552 (5.97%) patients were diagnosed with 13 different types of IEM. A total of 383 (4.1%) patients were diagnosed with aminoacidopathies, 167 (1.8%) patients were diagnosed with organic acidurias, and two (0.02%) patients were diagnosed with fatty acid oxidation disorders. Phenylketonuria is the most prevalent IEM of this study (2%) followed by maple syrup urine disease (0.98%). Conclusion The simultaneous analysis of amino acids and acylcarnitines in dried blood spots with analysis of organic acids in urine using mass spectrometry provides an integrated panel for the early detection of IEMs in early years of life, facilitating prompt provision of treatment and avoiding serious complications that can be fatal.

Targeted Lipidomics Analysis of Adipose and Skeletal Muscle Tissues by Multiple Reaction Monitoring Profiling.

Lipid homeostasis is critical for maintaining normal cellular functions including membrane structural integrity, cell metabolism, and signal transduction. Adipose tissue and skeletal muscle are two major tissues involved in lipid metabolism. Adipose tissue can store excessive lipids in the form of triacylglyceride(TG), which can be hydrolyzed to release free fatty acids (FFAs)under insufficient nutrition states. In the highly energy-demanding skeletal muscle, lipids serve as oxidative substrates for energy production but can cause muscle dysfunction when overloaded. Lipids undergo fascinating cycles of biogenesis and degradation depending on physiological demands, while dysregulation of lipid metabolism has been increasingly recognized as a hallmark of diseases such as obesity and insulin resistance. Thus, it is important to understand the diversity and dynamics of lipid composition in adipose tissue and skeletal muscle. Here, we describe the use of multiple reaction monitoring profiling, based on lipid class and fatty acyl chain specific fragmentation, to explore various classes of lipids in skeletal muscle and adipose tissues. We provide a detailed method for exploratory analysis of acylcarnitine (AC), ceramide (Cer), cholesteryl ester (CE), diacylglyceride (DG), FFA, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphatidylinositol (PI), phosphatidylserine (PS), sphingomyelin (SM), and TG. Characterization of lipid composition within adipose tissue and skeletal muscle under different physiological situations will provide biomarkers and therapeutic targets for obesity-related diseases.

Analysis of IVD gene variants in four children with isovalerate acidemia

To detect variants of IVD gene among 4 neonates with suspected isovalerate acidemia in order to provide a guidance for clinical treatment. 111 986 newborns and 7461 hospitalized children with suspected metabolic disorders were screened for acyl carnitine by tandem mass spectrometry. Those showing a significant increase in serum isovaleryl carnitine (C5) were analyzed for urinary organic acid and variants of the IVD gene. Four cases of isovalerate acidemia were detected, which included 2 asymptomatic newborns (0.018‰, 2/111 986) and 2 children suspected for metabolic genetic diseases (0.268‰, 2/7461). The formers had no obvious clinical symptoms. Analysis of acyl carnitine has suggested a significant increase in C5, and urinary organic acid analysis has shown an increase in isovaleryl glycine and 3-hydroxyisovalerate. Laboratory tests of the two hospitalized children revealed high blood ammonia, hyperglycemia, decreased red blood cells, white blood cells, platelets and metabolic acidosis. The main clinical manifestations have included sweaty foot-like odor, feeding difficulty, confusion, drowsiness, and coma. Eight variants (5 types) were detected, which included c.158G>A (p.Arg53His), c.214G>A (p.Asp72Asn), c.548C>T (p.Ala183Val), c.757A>G (p.Thr253Ala) and 1208A>G (p.Tyr403Cys). Among these, c.548C>T and c.757A>G were unreported previously. None of the variants was detected by next generation sequencing of 2095 healthy newborns, and all variants were predicted to be likely pathogenic based on the guidelines from the American College of Medical Genetics and Genomics. The incidence of isovalerate acidemia in Liuzhou area is quite high. Screening of metabolic genetic diseases is therefore recommended for newborns with abnormal metabolism. The discovery of novel variants has enriched the mutational spectrum of the IVD gene.

The serum acylcarnitines profile in epileptic children treated with valproic acid and the protective roles of peroxisome proliferator-activated receptor a activation in valproic acid-induced liver injury.

Valproic acid (VPA) is widely used as a major drug in the treatment of epilepsy. Despite the undisputed pharmacological importance and effectiveness of VPA, its potential hepatotoxicity is still a major concern. Being a simple fatty acid, the hepatotoxicity induced by VPA has long been considered to be due primarily to its interference with fatty acid β-oxidation (β-FAO). The aim of this study was to investigate the biomarkers for VPA-induced abnormal liver function in epileptic children and to determine potential mechanisms of its liver injury. Targeted metabolomics analysis of acylcarnitines (ACs) was performed in children's serum. Metabolomic analysis revealed that VPA -induced abnormal liver function resulted in the accumulation of serum long-chain acylcarnitines (LCACs), and the reduced expression of β-FAO relevant genes (Carnitine palmitoyltrans-ferase (CPT)1, CPT2 and Long-chain acyl-CoA dehydrogenase (LCAD)), indicating the disruption of β-FAO. As direct peroxisome proliferator-activated receptor a (PPARα)- regulated genes, CPT1A, CPT2 and LCAD were up-regulated after treatment with PPARα agonist, fenofibrate (Feno), indicating the improvement of β-FAO. Feno significantly ameliorated the accumulation of various lipids in the plasma of VPA-induced hepatotoxic mice by activating PPARα, significantly reduced the plasma ACs concentration, and attenuated VPA-induced hepatic steatosis. Enhanced oxidative stress and induced by VPA exposure were significantly recovered using Feno treatment. In conclusion, this study indicates VPA-induced β-FAO disruption might lead to liver injury, and a significant Feno protective effect against VPA -induced hepatotoxicity through reversing fatty acid metabolism.

P.76 Gene variant and neuromuscular findings from a long-chain fatty acid oxidation disorder gene panel program

Long-chain fatty acid oxidation disorders (LC-FAOD) are rare, life-threatening, autosomal recessive conditions that can be diagnosed clinically with plasma acylcarnitine analysis and molecular testing. Undiagnosed LC-FAOD may present with hypoglycemia, cardiomyopathy, cardiac arrhythmias, and neuromuscular symptoms. Patients with a clinical diagnosis or suspicion of LC-FAOD are eligible for this no-charge, next-generation sequencing gene panel which includes 6 genes associated with LC-FAOD plus 18 genes associated with disorders that cause abnormal acylcarnitine profiles. As of 28 October 2021, LC-FAOD gene variants were identified in 153 (37%) of 417 patients tested, including 83 variants of uncertain significance (VUS), 8 likely pathogenic (LP), and 102 pathogenic (P) variants. Twenty-three patients had positive (2 P/LP) LC-FAOD results and 19 had potential positive (2 variants, at least 1 VUS) results. VUS resolution analysis led to the reclassification of 6 variants from VUS to LP or P. Five patients had variants in two or more LC-FAOD genes and 22 had variants in one LC-FAOD gene and one or more non-LC-FAOD genes. Fifty-one patients had only one LC-FAOD gene variant identified. The most common neuromuscular symptoms among patients ages ≥13 (76 reported) were myopathy (42), elevated creatine kinase (36), and rhabdomyolysis (30), and among patients <13 years (83 reported) were elevated creatine kinase (22), and myopathy (12). Program results demonstrate the diverse composition of gene variants in patients referred for LC-FAOD genetic testing. Approaches to resolve VUS and identify previously undetected variants in patients with suspected LC-FAOD are important and necessary.

Neonatal Hypoxic-Ischemic Brain Injury Alters Brain Acylcarnitine Levels in a Mouse Model.

Hypoxic-ischemic brain injury (HIBI) leads to depletion of ATP, mitochondrial dysfunction, and enhanced oxidant formation. Measurement of acylcarnitines may provide insight into mitochondrial dysfunction. Plasma acylcarnitine levels are altered in neonates after an HIBI, but individual acylcarnitine levels in the brain have not been evaluated. Additionally, it is unknown if plasma acylcarnitines reflect brain acylcarnitine changes. In this study, postnatal day 9 CD1 mouse pups were randomized to HIBI induced by carotid artery ligation, followed by 30 min at 8% oxygen, or to sham surgery and normoxia, with subgroups for tissue collection at 30 min, 24 h, or 72 h after injury (12 animals/group). Plasma, liver, muscle, and brain (dissected into the cortex, cerebellum, and striatum/thalamus) tissues were collected for acylcarnitine analysis by LC-MS. At 30 min after HIBI, acylcarnitine levels were significantly increased, but the differences resolved by 24 h. Palmitoylcarnitine was increased in the cortex, muscle, and plasma, and stearoylcarnitine in the cortex, striatum/thalamus, and cerebellum. Other acylcarnitines were elevated only in the muscle and plasma. In conclusion, although plasma acylcarnitine results in this study mimic those seen previously in humans, our data suggest that the plasma acylcarnitine profile was more reflective of muscle changes than brain changes. Acylcarnitine metabolism may be a target for therapeutic intervention after neonatal HIBI, though the lack of change after 30 min suggests a limited therapeutic window.

Targeted metabolomics analysis of amino acids and acylcarnitines as risk markers for diabetes by LC–MS/MS technique

Diabetes is a common chronic disease affecting millions of people worldwide. It underlies various complications and imposes many costs on individuals and society. Discovering early diagnostic biomarkers takes excellent insight into preventive plans and the best use of interventions. Therefore, in the present study, we aimed to evaluate the association between the level of amino acids and acylcarnitines and diabetes to develop diabetes predictive models. Using the targeted LC–MS/MS technique, we analyzed fasting plasma samples of 206 cases and 206 controls that were matched by age, sex, and BMI. The association between metabolites and diabetes was evaluated using univariate and multivariate regression analysis with adjustment for systolic and diastolic blood pressure and lipid profile. To deal with multiple comparisons, factor analysis was used. Participants' average age and BMI were 61.6 years, 28.9 kg/m2, and 55% were female. After adjustment, Factor 3 (tyrosine, valine, leucine, methionine, tryptophan, phenylalanine), 5 (C3DC, C5, C5OH, C5:1), 6 (C14OH, C16OH, C18OH, C18:1OH), 8 (C2, C4OH, C8:1), 10 (alanine, proline) and 11 (glutamic acid, C18:2OH) were positively associated with diabetes. Inline, factor 9 (C4DC, serine, glycine, threonine) and 12 (citrulline, ornithine) showed a reverse trend. Some amino acids and acylcarnitines were found as potential risk markers for diabetes incidents that reflected the disturbances in the several metabolic pathways among the diabetic population and could be targeted to prevent, diagnose, and treat diabetes.

A novel HADHA variant associated with an atypical moderate and late-onset LCHAD deficiency

BackgroundLong chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare inherited disease caused by pathogenic variants of HADHA gene. Along with signs common to fatty acid oxidation defects (FAOD), specific retina and heart alterations are observed. Because long-chain fatty acid oxidation is selectively affected, supplementations with short/medium-chain fats represent energetic sources bypassing the enzymatic blockade. Here, we report on an atypical presentation of the disease. MethodsClinical features were described with medical explorations including ophthalmic and cardiac examination. Biological underlying defects were investigated by measurements of biochemical metabolites and by fluxomic studies of mitochondrial β-oxidation. Whole exome sequencing and molecular validation of variants confirmed the diagnosis. ResultsThe patient has developed at nine years an unlabeled maculopathy, and at 28 years, an acute cardiac decompensation without any premise. Blood individual acylcarnitine analysis showed a rise in hydroxylated long-chain fatty acids and fluxomic studies validated enzyme blockade consistent with LCHADD. Genetic analysis revealed the common p.(Glu510Gln) variant in HADHA, in trans with a novel variant c.1108G > A, p.(Gly370Arg) located in the NAD binding domain. Patient pathology was responsive to triheptanoin supplementation. ConclusionThis atypical LCHADD form report should encourage the early assessment of biochemical and genetic testing as a specific management is recommended (combination with fast avoidance, low fat-high carbohydrate diet, medium-even-chain triglycerides or triheptanoin supplementation).

EP001: Newborn screening experience for very long chain Acyl-CoA Dehydrogenase (VLCAD) deficiency in Kuwait

Among the various inborn errors of fatty acid oxidation disorders, very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is the most common disorder in Kuwaiti population, which has been noticed especially following the launch of the expanded newborn screening program in Kuwait in October 2014. VLCAD deficiency is a rare autosomal recessive disorder with a worldwide incidence of 1:30,000 to 1:100,000 births. It is caused by deficiency of VLCAD coenzyme, encoded by ACADVL gene which converts very-long-chain fatty acids into energy. In October 2014, the Kuwait Ministry of Health has started a publicly funded expanded newborn screening program meeting the highest international standards to screen for a wide range of metabolic and endocrine disorders including a total of 22 disorders via testing dried blood spots and thus replacing the old, limited newborn screening for congenital hypothyroidism and phenylketonuria that was introduced in 2005. A retrospective analysis of the data registry for the newborn screening over the 6-year period between January 2015 and December 2020 in Kuwait has been conducted after obtaining consent from the newborn screening program. This data included newborns delivered in hospitals all over Kuwait. Data on metabolite concentrations in dried blood spots at the time of screening obtained from all newborns were reviewed and only dried blood spots detecting elevated blood C14:1 (cutoff 0.29 mmol/L) and C14:1/C2 ratio (cutoff 0.03) via tandem mass spectrometry (MS/MS) were included in this study. The positive initial screening is followed by a confirmatory plasma or dried blood acylcarnitine analysis (cutoff ≥ 1 mmol/L) with or without a follow-up genetic analysis of ACADVL gene, either targeted variant testing using PCR amplification followed by Sanger sequencing, or through next generation sequencing technology. Total of 36 cases (19 male/17 female) out of 304,086 screened newborns have been identified and confirmed to have VLCAD deficiency with an incidence of ∼1:8300. The diagnosis was based on the detection of elevated blood C14:1 and C14:1/C2 ratio in the initial dried blood spots in the newborn screening, followed by a confirmatory plasma or dried blood acylcarnitines profile for VLCAD deficiency with or without a follow-up genetic analysis, except for three babies who had positive initial screen but have died before obtaining confirmatory acylcarnitine or genetic analyses. Out of the 36 individuals, there were 3 cases from Kingdom of Saudi Arabia, 2 cases from India and the rest were Kuwaiti. Molecular testing of 24 of them has revealed a founder truncating pathogenic variant in exon 2 of the ACADVL gene, * c.65C>A; p.(Ser22Ter); the reference transcript is NM_001178008.2(hg19/GRCh3). We have identified three genetically confirmed cases with VLCAD deficiency following a positive initial screen but negative confirmatory acylcarnitine analysis. Furthermore, we identified four heterozygous individuals for VLCAD deficiency via molecular testing, after a positive initial newborn screening and normal confirmatory acylcarnitine profile. This is the first study to review the Kuwaiti newborn screening experience of VLCAD deficiency since its launch in October 2014. We recommend including molecular genetic testing for ACADVL gene as part of the newborn screening for VLCAD deficiency particularly for the cases with negative confirmatory acylcarnitine profile. Our study provides evidence that the expanded newborn screening in Kuwait has led to the early detection of VLCAD deficiency cases and thus the initiation of the adequate management plan for these individuals aiming to prevent death and disability.

EP222: Gene variant and neuromuscular findings from a long-chain fatty acid oxidation disorder gene panel program

Long-chain fatty acid oxidation disorders (LC-FAOD) are rare, life-threatening, autosomal recessive conditions that impair the utilization of fats for energy production. LC-FAOD may initially be suspected based on clinical symptoms or positive results from newborn screening and can be confirmed clinically with plasma acylcarnitine analysis and molecular testing. Undiagnosed LC-FAOD may present with hypoglycemia, cardiomyopathy, cardiac arrhythmias, and with neuromuscular involvement, including rhabdomyolysis and myopathy.