The implementation of whole-exome sequencing in clinical diagnostics has generated a need for functional evaluation of genetic variants. In the field of inborn errors of metabolism (IEM), a diverse spectrum of targeted biochemical assays is employed to analyze a limited amount of metabolites. We now present a single-platform, high-resolution liquid chromatography quadrupole time of flight (LC-QTOF) method that can be applied for holistic metabolic profiling in plasma of individual IEM-suspected patients. This method, which we termed “next-generation metabolic screening” (NGMS), can detect >10,000 features in each sample. In the NGMS workflow, features identified in patient and control samples are aligned using the “various forms of chromatography mass spectrometry (XCMS)” software package. Subsequently, all features are annotated using the Human Metabolome Database, and statistical testing is performed to identify significantly perturbed metabolite concentrations in a patient sample compared with controls. We propose three main modalities to analyze complex, untargeted metabolomics data. First, a targeted evaluation can be done based on identified genetic variants of uncertain significance in metabolic pathways. Second, we developed a panel of IEM-related metabolites to filter untargeted metabolomics data. Based on this IEM-panel approach, we provided the correct diagnosis for 42 of 46 IEMs. As a last modality, metabolomics data can be analyzed in an untargeted setting, which we term “open the metabolome” analysis. This approach identifies potential novel biomarkers in known IEMs and leads to identification of biomarkers for as yet unknown IEMs. We are convinced that NGMS is the way forward in laboratory diagnostics of IEMs.Electronic supplementary materialThe online version of this article (10.1007/s10545-017-0131-6) contains supplementary material, which is available to authorized users.

We identified biallelic mutations in NANS, the gene encoding the synthase for N-acetylneuraminic acid (NeuNAc; sialic acid), in nine individuals with infantile-onset severe developmental delay and skeletal dysplasia. Patient body fluids showed an elevation in N-acetyl-D-mannosamine levels, and patient-derived fibroblasts had reduced NANS activity and were unable to incorporate sialic acid precursors into sialylated glycoproteins. Knockdown of nansa in zebrafish embryos resulted in abnormal skeletal development, and exogenously added sialic acid partially rescued the skeletal phenotype. Thus, NANS-mediated synthesis of sialic acid is required for early brain development and skeletal growth. Normal sialylation of plasma proteins was observed in spite of NANS deficiency. Exploration of endogenous synthesis, nutritional absorption, and rescue pathways for sialic acid in different tissues and developmental phases is warranted to design therapeutic strategies to counteract NANS deficiency and to shed light on sialic acid metabolism and its implications for human nutrition. DOI: https://doi.org/10. 1038/ng.3578 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-130493 Accepted Version Originally published at: van Karnebeek, Clara D M; Bonafé, Luisa; Wen, Xiao-Yan; Tarailo-Graovac, Maja; Balzano, Sara; RoyerBertrand, Beryl; Ashikov, Angel; Garavelli, Livia; Mammi, Isabella; Turolla, Licia; Breen, Catherine; Donnai, Dian; Cormier, Valerie; Heron, Delphine; Nishimura, Gen; Uchikawa, Shinichi; Campos-Xavier, Belinda; Rossi, Antonio; Hennet, Thierry; Brand-Arzamendi, Koroboshka; Rozmus, Jacob; Harshman, Keith; Stevenson, Brian J; Girardi, Enrico; Superti-Furga, Giulio; Dewan, Tammie; Collingridge, Alissa; Halparin, Jessie; Ross, Colin J; Van Allen, Margot I;et al (2016). NANS-mediated synthesis of sialic acid is required for brain and skeletal development. Nature Genetics, 48 (7) insights into the molecular basis of neurocognitive impairment allows for the development and 89 application of targeted therapeutic strategies 5 . Although less frequent than IDD, genetic disorders 90 affecting skeletal development and growth (commonly called the "skeletal dysplasias") are a 91 group of over 500 distinct disorders 6 . Studying their molecular basis has provided precious 92 insights into the many factors necessary for skeletal development, ranging from minerals and 93 structural molecules to enzymes, to signaling molecules and transcription factors 6,7 . We report 94here a genetic disorder presenting with a combination of severe IDD with skeletal dysplasia and 95 short stature. Our data show that its pathogenic basis is an inborn error of metabolism that 96 affects the endogenous synthesis of N-acetyl neuraminic acid (NeuNAc; sialic acid). Exploration 97 of the biochemical and molecular features of this disorder provides new information on the role 98 of sialic acid in the development of brain and bone. 99 100 RESULTS 101 Clinical and radiographic phenotype of N...

Aims/hypothesisObesity induces macrophages to drive inflammation in adipose tissue, a crucial step towards the development of type 2 diabetes. The tricarboxylic acid (TCA) cycle intermediate succinate is released from cells under metabolic stress and has recently emerged as a metabolic signal induced by proinflammatory stimuli. We therefore investigated whether succinate receptor 1 (SUCNR1) could play a role in the development of adipose tissue inflammation and type 2 diabetes.MethodsSuccinate levels were determined in human plasma samples from individuals with type 2 diabetes and non-diabetic participants. Succinate release from adipose tissue explants was studied. Sucnr1 −/− and wild-type (WT) littermate mice were fed a high-fat diet (HFD) or low-fat diet (LFD) for 16 weeks. Serum metabolic variables, adipose tissue inflammation, macrophage migration and glucose tolerance were determined.ResultsWe show that hypoxia and hyperglycaemia independently drive the release of succinate from mouse adipose tissue (17-fold and up to 18-fold, respectively) and that plasma levels of succinate were higher in participants with type 2 diabetes compared with non-diabetic individuals (+53%; p < 0.01). Sucnr1 −/− mice had significantly reduced numbers of macrophages (0.56 ± 0.07 vs 0.92 ± 0.15 F4/80 cells/adipocytes, p < 0.05) and crown-like structures (0.06 ± 0.02 vs 0.14 ± 0.02, CLS/adipocytes p < 0.01) in adipose tissue and significantly improved glucose tolerance (p < 0.001) compared with WT mice fed an HFD, despite similarly increased body weights. Consistently, macrophages from Sucnr1 −/− mice showed reduced chemotaxis towards medium collected from apoptotic and hypoxic adipocytes (−59%; p < 0.05).Conclusions/interpretationOur results reveal that activation of SUCNR1 in macrophages is important for both infiltration and inflammation of adipose tissue in obesity, and suggest that SUCNR1 is a promising therapeutic target in obesity-induced type 2 diabetes.Data availabilityThe dataset generated and analysed during the current study is available in GEO with the accession number GSE64104, www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE64104.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-017-4261-z) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

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Small molecule identification is a continually expanding field of research and represents the core challenge in various areas of (bio)analytical science, including metabolomics. Here, we unequivocally differentiate enantiomeric N-acetylhexosamines in body fluids using infrared ion spectroscopy, providing orthogonal identification of molecular structure unavailable by standard liquid chromatography/high-resolution tandem mass spectrometry. These results illustrate the potential of infrared ion spectroscopy for the identification of small molecules from complex mixtures.

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Background: Many severe diseases are caused by defects in lipid metabolism. As a result, patients often accumulate unusual lipids in their blood and tissues, and proper identification of these lipids is essential for correct diagnosis. In this study, we investigated the potential use of proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy to simultaneously identify and quantify (un)usual lipids present in the blood of patients with different inborn errors of lipid metabolism. Methods: We extracted blood plasma or serum lipids in chloroform-methanol (2:1 by volume). After addition of the nonvolatile chemical shift and concentration reference compound octamethylcyclotetrasiloxane, we performed

Selenium binding protein1 (SELENBP1) has been associated with several cancers. Its exact role was unknown. We show that SELENBP1 is a methanethiol oxidase (MTO), related to MTO of methylotrophic bacteria, converting methanethiol to H2O2, formaldehyde and H2S, an activity not known to exist in humans. Mutations in SELENBP1 were found in five patients with a cabbage-like smelling breath. Increased levels of methanethiol and dimethylsulfide are the main odorous compounds in their breath and responsible for the malodor. Increased urinary excretion of dimethylsulfoxide is a diagnostic biomarker of MTO-deficiency. Patient fibroblasts showed reduced amounts of SELENBP1 protein and deficient MTO enzymatic activity which could be restored by lentiviral-mediated expression of the wild-type SELENBP1 gene. A knockout mouse line showed the same biochemical characteristics. Our data define a novel inborn error of metabolism caused by MTO-deficiency leading to a malodor syndrome. MTO deficiency may be a frequent inborn error of metabolism.