A Solve-RD ClinVar-based reanalysis of 1522 index cases from ERN-ITHACA reveals common pitfalls and misinterpretations in exome sequencing

Purpose Within the Solve-RD project (https://solve-rd.eu/), the European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies aimed to investigate whether a reanalysis of exomes from unsolved cases based on ClinVar annotations could establish additional diagnoses. We present the results of the “ClinVar low-hanging fruit” reanalysis, reasons for the failure of previous analyses, and lessons learned. Methods Data from the first 3576 exomes (1522 probands and 2054 relatives) collected from European Reference Network for Intellectual disability, TeleHealth, Autism and Congenital Anomalies was reanalyzed by the Solve-RD consortium by evaluating for the presence of single-nucleotide variant, and small insertions and deletions already reported as (likely) pathogenic in ClinVar. Variants were filtered according to frequency, genotype, and mode of inheritance and reinterpreted. Results We identified causal variants in 59 cases (3.9%), 50 of them also raised by other approaches and 9 leading to new diagnoses, highlighting interpretation challenges: variants in genes not known to be involved in human disease at the time of the first analysis, misleading genotypes, or variants undetected by local pipelines (variants in off-target regions, low quality filters, low allelic balance, or high frequency). Conclusion The “ClinVar low-hanging fruit” analysis represents an effective, fast, and easy approach to recover causal variants from exome sequencing data, herewith contributing to the reduction of the diagnostic deadlock

Biological and environmental influence on tissue fatty acid compositions in wild tropical tunas

International audienceThis study examined the fatty acid composition of three sympatric tropical tuna species (bigeye Thunnus obesus, yellowfin T. albacares and skipjack tuna Kastuwonus pelamis) sampled in the Western Indian Ocean in 2013. The fatty acid compositions of neutral and polar lipids, respectively involved in energy storage and cell membrane structure, were explored and compared in four tissues (red and white muscles, liver and gonads), according to biological (size, sex and maturity) and environmental (season and area) factors. The liver and the red muscle were the fattest tissues (i.e., higher levels of storage lipids) in all species and polar lipids were the lowest in the white muscle. Species and tissue types explained most differences in fatty acid compositions, while environmental factors had limited effects, except in the hepatic cell membrane where fatty acid composition varied with monsoons. Docosahexaenoic acid (22:6n-3) was the major fatty acid in both polar and neutral lipid fractions, especially in muscles. Eicosapentaenoic acid (20:5n-3) and oleic acid (18:1n-9) were in higher proportion in neutral than in polar lipids. Arachidonic acid (20:4n-6) and 22:6n-3, together with docosapentaenoic acid (22:5n-6) and stearic acid (18:0), showed preferential accumulation in polar lipids. 20:4n-6 was particularly involved in cell membranes of ovary and white muscle. Overall, an important inter-individual variability in fatty acid compositions of structural lipids was found within tissue types despite considering biological factors that are most likely to influence this type of lipids. It suggests that fatty acid profiles are influenced by individual-specific behaviors

Comparison of the Phytochemical Composition of Serenoa repens Extracts by a Multiplexed Metabolomic Approach

International audiencePhytochemical extracts are highly complex chemical mixtures. In the context of an increasing demand for phytopharmaceuticals, assessment of the phytochemical equivalence of extraction procedures is of utmost importance. Compared to routine analytical methods, comprehensive metabolite profiling has pushed forward the concept of phytochemical equivalence. In this study, an untargeted metabolomic approach was used to cross-compare four marketed extracts from Serenoa repens obtained with three different extraction processes: ethanolic, hexanic and sCO2 (supercritical carbon dioxide). Our approach involved a biphasic extraction of native compounds followed by liquid chromatography coupled to a high-resolution mass spectrometry based metabolomic workflow. Our results showed significant differences in the contents of major and minor compounds according to the extraction solvent used. The analyses showed that ethanolic extracts were supplemented in phosphoglycerides and polyphenols, hexanic extracts had higher amounts of free fatty acids and minor compounds, and sCO2 samples contained more glycerides. The discriminant model in this study could predict the extraction solvent used in commercial samples and highlighted the specific biomarkers of each process. This metabolomic survey allowed the authors to assess the phytochemical content of extracts and finished products of S. repens and unequivocally established that sCO2, hexanic and ethanolic extracts are not chemically equivalent and are therefore unlikely to be pharmacologically equivalent

A metabolomic approach to identify anti-hepatocarcinogenic compounds from plants used traditionally in the treatment of liver diseases

International audienceLiver cancer is a major health burden in Southeast Asia, and most patients turn towards the use of medicinal plants to alleviate their symptoms. The aim of this work was to apply to Southeast Asian plants traditionally used to treat liver disorders, a successive ranking strategy based on a comprehensive review of the literature and metabolomic data in order to relate ethnopharmacological relevance to chemical entities of interest. We analyzed 45 publications resulting in a list of 378 plant species, and our point system based on the frequency of citation in the literature allowed the selection of 10 top ranked species for further collection and extraction. Extracts of these plants were tested for their in vitro anti-proliferative activities on HepG2 cells. Ethanolic extracts of Andrographis paniculata, Oroxylum indicum, Orthosiphon aristatus and Willughbeia edulis showed the highest anti-proliferative effects (IC50 = 195.9, 64.1, 71.3 and 66.7 μg/ml, respectively). A metabolomic ranking model was performed to annotate compounds responsible for the anti-proliferative properties of A. paniculata (andrographolactone and dehydroandrographolide), O. indicum (baicalein, chrysin, oroxylin A and scutellarein), O. aristatus (5-desmethylsinensetin) and W. edulis (parabaroside C and procyanidin). Overall, our dereplicative approach combined with a bibliographic scoring system allowed us to rapidly decipher the molecular basis of traditionally used medicinal plants

Analyse métabolomique LC-HRMS de foies de ratons exposés in-utero au Bisphénol A

Analyse métabolomique LC-HRMS de foies de ratons exposés in-utero au Bisphénol A. 10. Journées scientifiques du Réseau Francophone de Métabolomique et Fluxomique RFMF 201

NMR-based metabolic profiling and discrimination of wild tropical tunas by species, size category, geographic origin, and on-board storage condition

International audienceTunas are among the most traded and valued fish species, and good traceability of tuna products in the world market is needed to protect both consumers and tuna stocks. To that purpose, high-resolution proton nuclear magnetic resonance (1H NMR) spectroscopy combined with multivariate data analysis was used to investigate the molecular components of the aqueous extract of white and red muscles in three species of wild tropical tuna species, namely yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis) and bigeye tuna (T. obesus). Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) applied to the processed 1H NMR spectra showed significant separation according to the species and size category (i.e., small tunas 80 cm fork length), the storage conditions on-board the purse-seine vessels (i.e., brine- vs deep-freezing), and the geographical origin (i.e., where the tuna was caught: Mozambique Channel vs western-central Indian Ocean). The major groups of metabolites responsible for differentiation in PLS-DA score plots were the dipeptides (anserine, carnosine) and organic acids (lactate, creatine/phosphocreatine) in the white muscle, and the free amino acids, essential nutrients (choline and its derivatives, phosphatidylethanolamine), dipeptides and organic acids in the red muscle. Our results showed that NMR-based metabolomics is a powerful tool to efficiently discriminate specific profiles among wild tuna species, raw muscle tissues, fish storage conditions and tuna geographical origin

Proton NMR enables the absolute quantification of aqueous metabolites and lipid classes in unique mouse liver samples

International audienceHepatic metabolites provide valuable information on the physiological state of an organism, and thus, they are monitored in many clinical situations. Typically, monitoring requires several analyses for each class of targeted metabolite, which is time consuming. The present study aimed to evaluate a proton nuclear magnetic resonance (1H-NMR) method for obtaining quantitative measurements of aqueous and lipidic metabolites. We optimized the extraction protocol, the standard samples, and the organic solvents for the absolute quantification of lipid species. To validate the method, we analyzed metabolic profiles in livers of mice fed three different diets. We compared our results with values obtained with conventional methods and found strong correlations. The 1H-NMR protocol enabled the absolute quantification of 29 aqueous metabolites and eight lipid classes. Results showed that mice fed a diet enriched in saturated fatty acids had higher levels of triglycerides, cholesterol ester, monounsaturated fatty acids, lactate, 3-hydroxy-butyrate, and alanine and lower levels of glucose, compared to mice fed a control diet. In conclusion, proton NMR provided a rapid overview of the main lipid classes (triglycerides, cholesterol, phospholipids, fatty acids) and the most abundant aqueous metabolites in liver

Modelling intrahepatic metabolic rewiring during the onset of obesity using arterio- venous blood metabolomics profiles

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Modelling hepatic metabolic changes during the onset of obesity using NMR metabolomics arterio-venous blood exploration in minipigs

Communication PostersSession AlimentationPhenotypic alterations associated with obesity are well known, but metabolic adaptations occurring during its onset are poorly characterized. This study aims at understanding the hepatic metabolic processes modulated during the onset of obesity by combining paired arterial and venous metabolome analyses with computational modeling. It relies on the principle that differences in the metabolite composition of blood flowing in and out of the liver reflect its metabolic functioning. Blood samples were collected in a mini-pig model of obesity [1], consisting in over nutrition with a high-fat-high-sucrose (HFHS diet) for 60 days. Blood was sampled at the fasting state in 5 catheterized mini-pigs from incoming (abdominal artery and portal vein) and outgoing hepatic vessels at days 0 and 60 of HFHS feeding. From 1H-NMR analyses, we identified metabolites with significantly changed levels between arterious and venous blood. Calculated 1H-NMR integration ratios between arterious and venous blood allowed us to identify the metabolites with significant positive (resp. negative) balance between inflow and outflow, reflecting a release (resp. uptake) by the liver. These data were analyzed within the frame of an hepatic genome-scale metabolic network model using constraint-based modeling approaches to predict the changes in intra-tissular metabolic fluxes [2]. Constraints were set on exchange reactions in the metabolic model to enforce uptake and release of metabolites in accordance to experimental data and in silico flux balance analysis methods were used to predict possible flux ranges for hepatic metabolic reactions. We predicted that HFHS was associated with changes in the glucose metabolism and the sources of gluconeogenesis, but also in the catabolism of tryptophan and lysine, for which further support was found through complementary biochemical and molecular analyses.Polakof S, et al. Metabolic adaptations to HFHS overfeeding: how whole body and tissues postprandial metabolic flexibility adapt in Yucatan mini-pigs. Eur J Nutr. 2018;57(1):119-35

Postprandial NMR-Based Metabolic Exchanges Reflect Impaired Phenotypic Flexibility across Splanchnic Organs in the Obese Yucatan Mini-Pig

The postprandial period represents one of the most challenging phenomena in whole-body metabolism, and it can be used as a unique window to evaluate the phenotypic flexibility of an individual in response to a given meal, which can be done by measuring the resilience of the metabolome. However, this exploration of the metabolism has never been applied to the arteriovenous (AV) exploration of organs metabolism. Here, we applied an AV metabolomics strategy to evaluate the postprandial flexibility across the liver and the intestine of mini-pigs subjected to a high fat-high sucrose (HFHS) diet for 2 months. We identified for the first time a postprandial signature associated to the insulin resistance and obesity outcomes, and we showed that the splanchnic postprandial metabolome was considerably affected by the meal and the obesity condition. Most of the changes induced by obesity were observed in the exchanges across the liver, where the metabolism was reorganized to maintain whole body glucose homeostasis by routing glucose formed de novo from a large variety of substrates into glycogen. Furthermore, metabolites related to lipid handling and energy metabolism showed a blunted postprandial response in the obese animals across organs. Finally, some of our results reflect a loss of flexibility in response to the HFHS meal challenge in unsuspected metabolic pathways that must be further explored as potential new events involved in early obesity and the onset of insulin resistance