Association Between Low Plasma Level of Citrulline Before Allogeneic Hematopoietic Cell Transplantation and Severe Gastrointestinal Graft vs Host Disease.

BACKGROUND & AIMS: The gastrointestinal form of acute graft vs host disease increases morbidity and mortality following allogeneic hematopoietic cell transplantation. Plasma levels of citrulline, a non-proteinogenic amino acid, indicate functional enterocyte mass. We measured citrulline in patients before allogeneic hematopoietic cell transplantation and investigated its association with incidence and severity of gastrointestinal graft vs host disease. METHODS: We performed a retrospective study with 191 patients (69 women, 122 men; median age of 52 years) who underwent allogeneic hematopoietic cell transplantation for hematological malignancies at a tertiary center of France from January 2013 through April 2015. Levels of citrulline in plasma samples collected 30 days before graft infusion were measured by high performance liquid chromatography with tandem mass spectrometry. We assigned patients to groups with a high level of citrulline (>26 µmol/L) or low level of citrulline (≤26 µmol/L). The primary outcomes were difference between groups in incidence of stage 2-4 gastrointestinal graft vs host disease, death without hematological disease relapse (non-relapse mortality), relapse of the hematological disease, and overall survival through 2 years after transplantation. RESULTS: Ninety-six patients (50%) developed acute graft vs host disease and 37 (19%) developed a gastrointestinal form. Among patients with gastrointestinal involvement, 33 patients (89%) had stage 2-4 gastrointestinal graft vs host disease. In univariable analysis, low level of citrulline associated with higher cumulative incidence of stage 2-4 gastrointestinal graft vs host disease, non-relapse mortality, and shorter overall survival. In multivariable analysis, low level of citrulline was the only risk factor independently associated with stage 2-4 gastrointestinal graft vs host disease (hazard ratio, 3.06; 95% CI, 1.37-6.85; P = .007); it also associated with increased non-relapse mortality (hazard ratio, 2.29; 95% CI, 1.24-4.22; P = .008). CONCLUSIONS: In a retrospective study with 191 patients, we associated a low plasma level of citrulline before allogeneic hematopoietic cell transplantation with a higher risk for stage 2-4 gastrointestinal graft vs host disease and non-relapse mortality. This marker might be used to manage patients before allogeneic hematopoietic cell transplantation.

Functional assessment of creatine transporter in control and X-linked SLC6A8-deficient fibroblasts.

Creatine transporter is currently the focus of renewed interest with emerging roles in brain neurotransmission and physiology, and the bioenergetics of cancer metastases. We here report on amendments of a standard creatine uptake assay which might help clinical chemistry laboratories to extend their current range of measurements of creatine and metabolites in body fluids to functional enzyme explorations. In this respect, short incubation times and the use of a stable-isotope-labeled substrate (D3-creatine) preceded by a creatine wash-out step from cultured fibroblast cells by removal of fetal bovine serum (rich in creatine) from the incubation medium are recommended. Together, these measures decreased, by a first order of magnitude, creatine concentrations in the incubation medium at the start of creatine-uptake studies and allowed to functionally discriminate between 4 hemizygous male and 4 heterozygous female patients with X-linked SLC6A8 deficiency, and between this cohort of eight patients and controls. The functional assay corroborated genetic diagnosis of SLC6A8 deficiency. Gene anomalies in our small cohort included splicing site (c.912G > A [p.Ile260_Gln304del], c.778-2A > G and c.1495 + 2 T > G), substitution (c.407C > T) [p.Ala136Val] and deletion (c.635_636delAG [p.Glu212Valfs*84] and c.1324delC [p.Gln442Lysfs*21]) variants with reduced creatine transporter function validating their pathogenicity, including that of a previously unreported c.1324delC variant. The present assay adaptations provide an easy, reliable and discriminative manner for exploring creatine transporter activity and disease variations. It might apply to drug testing or other evaluations in the genetic and metabolic horizons covered by the emerging functions of creatine and its transporter, in a way, however, requiring and completed by additional studies on female patients and blood-brain barrier permeability properties of selected compounds. As a whole, the proposed assay of creatine transporter positively adds to currently existing measurements of this transporter activity, and determining on a large scale the extent of its exact suitability to detect female patients should condition in the future its transfer in clinical practice.

Fluxomic assay-assisted diagnosis orientation in a cohort of 11 patients with myopathic form of CPT2 deficiency.

Carnitine palmitoyltransferase type 2 (CPT2) deficiency, a mitochondrial fatty acid oxidation disorder (MFAOD), is a cause of myopathy in its late clinical presentation. As for other MFAODs, its diagnosis may be evocated when blood acylcarnitine profile is abnormal. However, a lack of abnormalities or specificity in this profile is not exclusive of CPT2 deficiency. Our retrospective study reports clinical and biological data in a cohort of 11 patients with circulating acylcarnitine profile unconclusive enough for a specific diagnosis orientation. In these patients, CPT2 gene studies was prompted by prior fluxomic explorations of mitochondrial ß-oxidation on intact whole blood cells incubated with pentadeuterated ([16-2H3, 15-2H2])-palmitate. Clinical indication for fluxomic explorations was at least one acute rhabdomyolysis episode complicated, in 5 of 11 patients, by acute renal failure. Major trigger of rhabdomyolysis was febrile infection. In all patients, fluxomic data indicated deficient CPT2 function showing normal deuterated palmitoylcarnitine (C16-Cn) formation rates associated with increased ratios between generated C16-Cn and downstream deuterated metabolites (Σ deuterated C2-Cn to C14-Cn). Subsequent gene studies showed in all patients pathogenic gene variants in either homozygous or compound heterozygous forms. Consistent with literature data, allelic frequency of the c.338C > T[p.Ser113Leu] mutation amounted to 68.2% in our cohort. Other missense mutations included c.149C > A[p.Pro50His] (9%), c.200C > G[p.Ala200Gly] (4.5%) and previously unreported c.1171A > G[p.ser391Gly] (4.5%) and c.1420G > C[p.Ala474Pro] (4.5%) mutations. Frameshift c.1666-1667delTT[p.Leu556val*16] mutation (9%) was observed in two patients unknown to be related.

Citrulline and Monocyte-Derived Macrophage Reactivity before Conditioning Predict Acute Graft-versus-Host Disease.

During conditioning, intestinal damage induces microbial translocation which primes macrophage reactivity and leads to donor-derived T cell stimulation. Little is known about the role of intestinal health and macrophage reactivity before conditioning in the development of acute graft-versus-host disease (aGVHD) in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). We assessed (1) citrulline, a surrogate marker of functional enterocyte mass and (2) circulating monocyte-derived macrophage reactivity, before allo-HCT. Forty-seven consecutive patients were prospectively included. Citrulline levels from blood samples withdrawn 30 days before transplantation were assessed using liquid chromatography combined with mass spectrometry. Monocyte-derived macrophages were isolated and incubated with 5 pathogen-associated molecular patterns: lipopolysaccharide, PamCSK4, flagellin, muramyl dipeptide, and curdlan. Multiplex fluorescent immunoassay on culture supernatant assessed levels of TNF-α, IL-1ß, IL-6, and IL-10 in each condition. Citrulline and cytokine levels were analyzed relatively to aGVHD onset within 100 days after transplantation. Citrulline levels were lower in the aGVHD group (n = 20) than in the no-aGVHD group (n = 27) (P = .005). Conversely, IL-6 and IL-10 were greater in aGVHD group, especially after curdlan stimulation (P = .005 and P = .012). Citrulline levels ≤20 µmol/L, IL-6 ≥ 332 pg/mL, and IL-10 ≥ 90 pg/mL were associated with aGVHD development (log-rank test, P = .002, P = .041, and P < .0001, respectively). In multivariate analysis, IL-10 ≥ 90 pg/mL, myeloablative conditioning, and citrulline ≤20 µmol/L remained independent factors of aGVHD development (hazard ratio [HR], 8.18, P = .0003; HR, 4.28, P = .006; and HR, 4.43, P = .01, respectively). Preconditioning citrulline and monocyte-derived macrophage reactivity are objective surrogate markers suitable to identify patients at risk of developing aGVHD. This work highlights the influence of preconditioning status in aGVHD development.

A fast method for high resolution oxymetry study of skeletal muscle mitochondrial respiratory chain complexes.

High resolution oxymetry study (HROS) of skeletal muscle usually requires 90-120 min preparative phase (dissection, permeabilization and washing). This work reports on the suitability of a rapid muscle preparation which by-passes this long preparation. For a few seconds only, muscle biopsy from pigs is submitted to gentle homogenization at 8000 rotations per minute using an ultra-dispersor apparatus. Subsequent HROS is performed using FCCP instead of ADP, compounds crossing and not plasma membrane, respectively. This simplified procedure compares favorably with classical (permeabilized fibers) HROS in terms of respiratory chain complex activities. Mitochondria from cells undergoing ultradispersion were functionally preserved as attested by relative inefficacy of added cytochrome C (not crossing intact mitochondrial outer membrane) to stimulate mitochondrial respiration. Responsiveness of respiration to ADP (in the absence of FCCP) suggested that these intact mitochondria were outside cells disrupted by ultradispersion or within cells permeated by this procedure.

Alteration or adaptation, the two roads for human gastric mucin glycosylation infected by Helicobacter pylori.

Helicobacter pylori is a Gram-negative bacterium that colonizes the mucus niche of the gastric mucosa and infects more than half of the world's human population. Chronic infection may cause gastritis, duodenal ulcer, intestinal metaplasia or gastric cancer. In the stomach, H. pylori interacts with O-glycans of gastric mucins but the mechanism by which the bacteria succeed in altering the mucosa remains mainly unknown. To better understand the physiopathology of the infection, inhibitory adhesion assays were performed with various O-glycans expressed by human gastric mucins, and topographic expression of gastric mucins MUC5AC and MUC6 was analyzed for healthy uninfected individuals, for infected asymptomatic individuals and for patients infected by H. pylori and having the incomplete type of intestinal metaplasia. The glycosylation of the gastric mucosa of asymptomatic individuals infected by H. pylori was determined and compared with the glycosylation pattern found for patients with the incomplete type of intestinal metaplasia. Results show that H. pylori manages to modulate host's glycosylation during the course of infection in order to create a favorable niche, whereas asymptomatic infected individuals seem to counteract further steps of infection development by adapting their mucus glycosylation.

The lacdiNAc-specific adhesin LabA mediates adhesion of Helicobacter pylori to human gastric mucosa.

Adhesion of Helicobacter pylori to the gastric mucosa is a necessary prerequisite for the pathogenesis of H. pylori-related diseases. In this study, we investigated the GalNAcß1-4GlcNAc motif (also known as N,N'-diacetyllactosediamine [lacdiNAc]) carried by MUC5AC gastric mucins as the target for bacterial binding to the human gastric mucosa. The expression of LacdiNAc carried by gastric mucins was correlated with H. pylori localization, and all strains tested adhered significantly to this motif. Proteomic analysis and mutant construction allowed the identification of a yet uncharacterized bacterial adhesin, LabA, which specifically recognizes lacdiNAc. These findings unravel a target of adhesion for H. pylori in addition to moieties recognized by the well-characterized adhesins BabA and SabA. Localization of the LabA target, restricted to the gastric mucosa, suggests a plausible explanation for the tissue tropism of these bacteria. These results pave the way for the development of alternative strategies against H. pylori infection, using adherence inhibitors.

Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii influence the production of mucus glycans and the development of goblet cells in the colonic epithelium of a gnotobiotic model rodent.

BACKGROUND: The intestinal mucus layer plays a key role in the maintenance of host-microbiota homeostasis. To document the crosstalk between the host and microbiota, we used gnotobiotic models to study the influence of two major commensal bacteria, Bacteroides thetaiotaomicron and Faecalibacterium prausnitzii, on this intestinal mucus layer. B. thetaiotaomicron is known to use polysaccharides from mucus, but its effect on goblet cells has not been addressed so far. F. prausnitzii is of particular physiological importance because it can be considered as a sensor and a marker of human health. We determined whether B. thetaiotaomicron affected goblet cell differentiation, mucin synthesis and glycosylation in the colonic epithelium. We then investigated how F. prausnitzii influenced the colonic epithelial responses to B. thetaiotaomicron. RESULTS: B. thetaiotaomicron, an acetate producer, increased goblet cell differentiation, expression of mucus-related genes and the ratio of sialylated to sulfated mucins in mono-associated rats. B. thetaiotaomicron, therefore, stimulates the secretory lineage, favoring mucus production. When B. thetaiotaomicron was associated with F. prausnitzii, an acetate consumer and a butyrate producer, the effects on goblet cells and mucin glycosylation were diminished. F. prausnitzii, by attenuating the effects of B. thetaiotaomicron on mucus, may help the epithelium to maintain appropriate proportions of different cell types of the secretory lineage. Using a mucus-producing cell line, we showed that acetate up-regulated KLF4, a transcription factor involved in goblet cell differentiation. CONCLUSIONS: B. thetaiotaomicron and F. prausnitzii, which are metabolically complementary, modulate, in vivo, the intestinal mucus barrier by modifying goblet cells and mucin glycosylation. Our study reveals the importance of the balance between two main commensal bacteria in maintaining colonic epithelial homeostasis via their respective effects on mucus.

Virulent Shigella flexneri affects secretion, expression, and glycosylation of gel-forming mucins in mucus-producing cells.

Mucin glycoproteins are secreted in large amounts by the intestinal epithelium and constitute an efficient component of innate immune defenses to promote homeostasis and protect against enteric pathogens. In this study, our objective was to investigate how the bacterial enteropathogen Shigella flexneri, which causes bacillary dysentery, copes with the mucin defense barrier. We report that upon in vitro infection of mucin-producing polarized human intestinal epithelial cells, virulent S. flexneri manipulates the secretion of gel-forming mucins. This phenomenon, which is triggered only by virulent strains, results in accumulation of mucins at the cell apical surface, leading to the appearance of a gel-like structure that favors access of bacteria to the cell surface and the subsequent invasion process. We identify MUC5AC, a gel-forming mucin, as a component of this structure. Formation of this gel does not depend on modifications of electrolyte concentrations, induction of trefoil factor expression, endoplasmic reticulum stress, or response to unfolded proteins. In addition, transcriptional and biochemical analyses of infected cells reveal modulations of mucin gene expression and modifications of mucin glycosylation patterns, both of which are induced by virulent bacteria in a type III secretion system-dependent manner. Thus, S. flexneri has developed a dedicated strategy to alter the mucus barrier by targeting key elements of the gel-forming capacity of mucins: gene transcription, protein glycosylation, and secretion.

Creatine and guanidinoacetate reference values in a French population.

Creatine and guanidinoacetate are biomarkers of creatine metabolism. Their assays in body fluids may be used for detecting patients with primary creatine deficiency disorders (PCDD), a class of inherited diseases. Their laboratory values in blood and urine may vary with age, requiring that reference normal values are given within the age range. Despite the long known role of creatine for muscle physiology, muscle signs are not necessarily the major complaint expressed by PCDD patients. These disorders drastically affect brain function inducing, in patients, intellectual disability, autistic behavior and other neurological signs (delays in speech and language, epilepsy, ataxia, dystonia and choreoathetosis), being a common feature the drop in brain creatine content. For this reason, screening of PCDD patients has been repeatedly carried out in populations with neurological signs. This report is aimed at providing reference laboratory values and related age ranges found for a large scale population of patients with neurological signs (more than 6 thousand patients) previously serving as a background population for screening French patients with PCDD. These reference laboratory values and age ranges compare rather favorably with literature values for healthy populations. Some differences are also observed, and female participants are discriminated from male participants as regards to urine but not blood values including creatine on creatinine ratio and guanidinoacetate on creatinine ratio values. Such gender differences were previously observed in healthy populations; they might be explained by literature differential effects of testosterone and estrogen in adolescents and adults, and by estrogen effects in prepubertal age on SLC6A8 function. Finally, though they were acquired on a population with neurological signs, the present data might reasonably serve as reference laboratory values in any future medical study exploring abnormalities of creatine metabolism and transport.

Almost all human gastric mucin O-glycans harbor blood group A, B or H antigens and are potential binding sites for Helicobacter pylori.

Helicobacter pylori infects more than half of the world's population. Although most patients are asymptomatic, persistent infection may cause chronic gastritis and gastric cancer. Adhesion of the bacteria to the gastric mucosa is a necessary prerequisite for the pathogenesis of H. pylori-related diseases and is mediated by mucin O-glycans. In order to define which glycans may be implicated in the binding of the bacteria to the gastric mucosa in humans, we have characterized the exact pattern of glycosylation of gastric mucins. We have identified that the major component was always a core 2-based glycan carrying two blood group H antigens, whatever was the blood group of individuals. We have also demonstrated that around 80% of O-glycans carried blood group A, B or H antigens, suggesting that the variation of gastric mucin glycosylation between individuals is partly due to the blood group status. This study will help better understanding the role of O-glycans in the physiology and homeostasis of gastric mucosa. Overall, the results reported here give us the necessary background information to begin studies to determine whether individuals who express certain carbohydrate epitopes on specific mucins are predisposed to certain gastric diseases.

Guanidinoacetate methyltransferase (GAMT) deficiency in two Tunisian siblings: clinical and biochemical features.

BACKGROUND: Guanidinoacetate methyltransferase (GAMT) deficiency is a recently described disorder and few cases have been reported to date. As it is a treatable pathology, we seek to contribute to its better understanding, particularly to further elucidate its biochemical diagnosis for early treatment. METHODS: The patients, two brothers aged 13 years (P1) and 11 years (P2), have been explored for signs and symptoms suggestive of inborn errors of metabolism. The quantification of creatine (Cr), guanidinoacetate (GAA), and GAMT activity was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: The two brothers presented a similar clinical picture: developmental delay, epilepsy, axial hypotonia, spastic tetraparesis, severe mental and language delay, and autistic behaviour. GAA concentrations were markedly increased in plasma and in urine [2796 and 3342 micromol/mmol creatinine (control range: 4 - 220 micromol/mmol creatinine)/14 and 29 micromol/L (control range: 0.35 - 1.8 micromol/L), respectively] while plasma and urine creatine concentrations were at the lower normal range limit. Activity of GAMT in lymphoblasts was extremely reduced (< 0.01 nmol/mg protein/hour) compared to healthy subjects. GAMT activity was found to be intermediary in patients' parents. CONCLUSIONS: It appears that the clinical picture is heterogeneous but should be considered as potential signs of creatine metabolism disorders, however, the biochemical diagnosis is reliable as the enzyme activity is zero in most cases. To date, it is still too early to establish correlations between symptoms and biochemical profile. However, the identification of additional cases of GAMT deficiency should help elucidate such relationships and the progress of patients treated with creatine in conjunction with ornithine supplementation.

Nitrous oxide abuse in the emergency practice, and Review of toxicity mechanisms and potential markers.

Nitrous oxide (N2O) toxicity is a concern common to several medical fields. Here, retrospective study of four N2O abuses with neurological signs in the emergency practice provides a preliminary basis for a metabolic Discussion/Review. This latter highlights N2O abuse as pathology of DNA/RNA/protein methylations, for instance consistent with impairments of protein arginine methyltransferases involved in myelinogenesis and myelopathy in patients. Basically, pathogenesis starts with oxidation by N2O of coordinated cobalamine cobalt ions at enzyme sites with impairments of vitamin-B12-dependent pathways. Methionine synthase (methylcobalamine) and methymalonyl-CoA mutase (adenosylcobalamine) are inactivated and cofactor-depleted, respectively. The number of impacted pathways (folate cycle, methylation cycle, S-adenosylmethionine-dependent methyltransferases, transulfuration pathway, Krebs cycle fueling by methylmalonyl-CoA, glutathione synthesis) explains the variety of potential research/laboratory markers, and may provide new clues and future angles to explore N2O toxicity. Overall, homocysteine measurements obviously help diagnosis of N2O abuses. Additional markers may include vitamin-B12, methionine, methylmalonate, dimethylglycine, sarcosine, S-adenosylmethionine to S-adenosylhomocysteine ratio, various S-adenosylamino acids, S-adenosylmethionine-dependent cellular methylations, and additional analytes (propionylcarnitine, propionylglycine, cystathionine and derived metabolites, methylated amino acids [eg arginine], betaine).

Citrin deficiency: Does the reactivation of liver aralar-1 come into play and promote HCC development?

Hepatocellular carcinoma (HCC) is a longstanding issue in clinical practice and metabolic research. New clues in better understanding the pathogenesis of HCC might relate to the metabolic context in patients with citrin (aspartate-glutamate carrier 1) deficiency (CD). Because citrin-deficient liver (CDL) is subject to HCC, it represents a unique metabolic model to highlight the mechanisms of HCC promotion, offering different angles of study than the classical metabolic syndrome/obesity/non-alcoholic fatty liver disease (NAFLD)/HCC study axis. In turn, the metabolic features of HCC could shed light on the pathogenesis of CDL. Among these, HCC-induced re-activation of aralar-1 (aspartate-glutamate carrier 2), physiologically not expressed in the adult liver, might take place in CDL, so gene redundancy for mitochondrial aspartate-glutamate carriers would be exploited by the CDL. This proposed (aralar-1 re-activation) and known (citrate/malate cycle) adaptive mechanisms may substitute for the impaired function in CD and are consistent with the clinical remission stage of CD and CD improvement by medium-chain triglycerides (MCT). However, these metabolic adaptive benefits could also promote HCC development. In CD, as a result of PPARα down-regulation, liver mitochondrial fatty acid-derived acetyl-CoA would, like glucose-derived acetyl-CoA, be used for lipid anabolism and fuel nuclear acetylation events which might trigger aralar-1 re-activation as seen in non-CD HCC. A brief account of these metabolic events which might lead to aralar-1 re-activation in CDL is here given. Consistency of this account for CDL events further relies on the protective roles of PPARα and inhibition of mitochondrial and plasma membrane citrate transporters in non-CD HCC.

Glucose metabolism and NRF2 coordinate the antioxidant response in melanoma resistant to MAPK inhibitors.

Targeted therapies as BRAF and MEK inhibitor combination have been approved as first-line treatment for BRAF-mutant melanoma. However, disease progression occurs in most of the patients within few months of therapy. Metabolic adaptations have been described in the context of acquired resistance to BRAF inhibitors (BRAFi). BRAFi-resistant melanomas are characterized by an increase of mitochondrial oxidative phosphorylation and are more prone to cell death induced by mitochondrial-targeting drugs. BRAFi-resistant melanomas also exhibit an enhancement of oxidative stress due to mitochondrial oxygen consumption increase. To understand the mechanisms responsible for survival of BRAFi-resistant melanoma cells in the context of oxidative stress, we have established a preclinical murine model that accurately recapitulates in vivo the acquisition of resistance to MAPK inhibitors including several BRAF or MEK inhibitors alone and in combination. Using mice model and melanoma cell lines generated from mice tumors, we have confirmed that the acquisition of resistance is associated with an increase in mitochondrial oxidative phosphorylation as well as the importance of glutamine metabolism. Moreover, we have demonstrated that BRAFi-resistant melanoma can adapt mitochondrial metabolism to support glucose-derived glutamate synthesis leading to increase in glutathione content. Besides, BRAFi-resistant melanoma exhibits a strong activation of NRF-2 pathway leading to increase in the pentose phosphate pathway, which is involved in the regeneration of reduced glutathione, and to increase in xCT expression, a component of the xc-amino acid transporter essential for the uptake of cystine required for intracellular glutathione synthesis. All these metabolic modifications sustain glutathione level and contribute to the intracellular redox balance to allow survival of BRAFi-resistant melanoma cells.

Fluxomic evidence for impaired contribution of short-chain acyl-CoA dehydrogenase to mitochondrial palmitate ß-oxidation in symptomatic patients with ACADS gene susceptibility variants.

BACKGROUND: Despite ACADS (acyl-CoA dehydrogenase, short-chain) gene susceptibility variants (c.511C>T and c.625G>A) are considered to be non-pathogenic, encoded proteins are known to exhibit altered kinetics. Whether or not, they might affect overall fatty acid ß-oxidation still remains, however, unclear. METHODS: De novo biosynthesis of acylcarnitines by whole blood samples incubated with deuterated palmitate (16-2H3,15-2H2-palmitate) is suitable as a fluxomic exploration to distinguish between normal and disrupted ß-oxidation, abnormal profiles and ratios of acylcarnitines with different chain-lengths being indicative of the site for enzymatic blockade. Determinations in 301 control subjects of ratios between deuterated butyrylcarnitine and sum of deuterated C2 to C14 acylcarnitines served here as reference values to state specifically functional SCAD impairment in patients addressed for clinical and/or biological suspicion of a ß-oxidation disorder. RESULTS: Functional SCAD impairment was found in 39 patients. The 27 patients accepting subsequent gene studies were all positive for ACADS mutations. Twenty-six of 27 patients were positive for c.625G>A variant. Twenty-three of 27 patients harbored susceptibility variants as sole ACADS alterations (18 homozygous and 3 heterozygous for c.625G>A, 2 compound heterozygous for c.625G>A/c.511C>T). CONCLUSION: Our present fluxomic assessment of SCAD suggests a link between ACADS susceptibility variants and abnormal ß-oxidation consistent with known altered kinetics of these variants.