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.

The antioxidant l-Ergothioneine prevents cystine lithiasis in the Slc7a9-/- mouse model of cystinuria.

The high recurrence rate of cystine lithiasis observed in cystinuria patients highlights the need for new therapeutic options to address this chronic disease. There is growing evidence of an antioxidant defect in cystinuria, which has led to test antioxidant molecules as new therapeutic approaches. In this study, the antioxidant l-Ergothioneine was evaluated, at two different doses, as a preventive and long-term treatment for cystinuria in the Slc7a9-/- mouse model. l-Ergothioneine treatments decreased the rate of stone formation by more than 60% and delayed its onset in those mice that still developed calculi. Although there were no differences in metabolic parameters or urinary cystine concentration between control and treated mice, cystine solubility was increased by 50% in the urines of treated mice. We also demonstrate that l-Ergothioneine needs to be internalized by its transporter OCTN1 (Slc22a4) to be effective, as when administrated to the double mutant Slc7a9-/-Slc22a4-/- mouse model, no effect on the lithiasis phenotype was observed. In kidneys, we detected a decrease in GSH levels and an impairment of maximal mitochondrial respiratory capacity in cystinuric mice that l-Ergothioneine treatment was able to restore. Thus, l-Ergothioneine administration prevented cystine lithiasis in the Slc7a9-/- mouse model by increasing urinary cystine solubility and recovered renal GSH metabolism and mitochondrial function. These results support the need for clinical trials to test l-Ergothioneine as a new treatment for cystinuria.

Fibroblast phenylalanine concentration as a surrogate biomarker of cellular number.

Metabolomics studies in human dermal fibroblasts can elucidate the biological mechanisms associated with some diseases, but several methodological issues that increase variability have been identified. We aimed to quantify the amino acid levels in cultured fibroblasts and to apply different sample-based normalization approaches. Forty-four skin biopsies from control subjects were collected. Amino acids were measured in fibroblasts supernatants by UPLC-MS/MS. Statistical supervised and unsupervised studies were used. Spearman's test showed that phenylalanine displayed the second highest correlation with the remaining amino acids (mean r = 0.8), whereas the total protein concentration from the cell pellet showed a mean of r = 0.67. The lowest percentage of variation was obtained when amino acids were normalized by phenylalanine values, with a mean of 42% vs 57% when normalized by total protein values. When amino acid levels were normalized by phenylalanine, Principal Component Analysis and clustering analyses identified different fibroblasts groups. In conclusion, phenylalanine may be a suitable biomarker to estimate cellular content in cultured fibroblasts.

Unravelling inclusion body myositis using a patient-derived fibroblast model.

BACKGROUND: Inclusion body myositis (IBM) is an inflammatory myopathy clinically characterized by proximal and distal muscle weakness, with inflammatory infiltrates, rimmed vacuoles and mitochondrial changes in muscle histopathology. There is scarce knowledge on IBM aetiology, and non-established biomarkers or effective treatments are available, partly due to the lack of validated disease models. METHODS: We have performed transcriptomics and functional validation of IBM muscle pathological hallmarks in fibroblasts from IBM patients (n = 14) and healthy controls (n = 12), paired by age and sex. The results comprise an mRNA-seq, together with functional inflammatory, autophagy, mitochondrial and metabolic changes between patients and controls. RESULTS: Gene expression profile of IBM vs control fibroblasts revealed 778 differentially expressed genes (P-value adj < 0.05) related to inflammation, mitochondria, cell cycle regulation and metabolism. Functionally, an increased inflammatory profile was observed in IBM fibroblasts with higher supernatant cytokine secretion (three-fold increase). Autophagy was reduced considering basal protein mediators (18.4% reduced), time-course autophagosome formation (LC3BII 39% reduced, P-value < 0.05), and autophagosome microscopic evaluation. Mitochondria displayed reduced genetic content (by 33.9%, P-value < 0.05) and function (30.2%-decrease in respiration, 45.6%-decline in enzymatic activity (P-value < 0.001), 14.3%-higher oxidative stress, 135.2%-increased antioxidant defence (P-value < 0.05), 11.6%-reduced mitochondrial membrane potential (P-value < 0.05) and 42.8%-reduced mitochondrial elongation (P-value < 0.05)). In accordance, at the metabolite level, organic acid showed a 1.8-fold change increase, with conserved amino acid profile. Correlating to disease evolution, oxidative stress and inflammation emerge as potential markers of prognosis. CONCLUSIONS: These findings confirm the presence of molecular disturbances in peripheral tissues from IBM patients and prompt patients' derived fibroblasts as a promising disease model, which may eventually be exported to other neuromuscular disorders. We additionally identify new molecular players in IBM associated with disease progression, setting the path to deepen in disease aetiology, in the identification of novel biomarkers or in the standardization of biomimetic platforms to assay new therapeutic strategies for preclinical studies.

Disrupted Mitochondrial and Metabolic Plasticity Underlie Comorbidity between Age-Related and Degenerative Disorders as Parkinson Disease and Type 2 Diabetes Mellitus.

Idiopathic Parkinson's disease (iPD) and type 2 diabetes mellitus (T2DM) are chronic, multisystemic, and degenerative diseases associated with aging, with eventual epidemiological co-morbidity and overlap in molecular basis. This study aims to explore if metabolic and mitochondrial alterations underlie the previously reported epidemiologic and clinical co-morbidity from a molecular level. To evaluate the adaptation of iPD to a simulated pre-diabetogenic state, we exposed primary cultured fibroblasts from iPD patients and controls to standard (5 mM) and high (25 mM) glucose concentrations to further characterize metabolic and mitochondrial resilience. iPD fibroblasts showed increased organic and amino acid levels related to mitochondrial metabolism with respect to controls, and these differences were enhanced in high glucose conditions (citric, suberic, and sebacic acids levels increased, as well as alanine, glutamate, aspartate, arginine, and ornithine amino acids; p-values between 0.001 and 0.05). The accumulation of metabolites in iPD fibroblasts was associated with (and probably due to) the concomitant mitochondrial dysfunction observed at enzymatic, oxidative, respiratory, and morphologic level. Metabolic and mitochondrial plasticity of controls was not observed in iPD fibroblasts, which were unable to adapt to different glucose conditions. Impaired metabolism and mitochondrial activity in iPD may limit energy supply for cell survival. Moreover, reduced capacity to adapt to disrupted glucose balance characteristic of T2DM may underlay the co-morbidity between both diseases. Conclusions: Fibroblasts from iPD patients showed mitochondrial impairment, resulting in the accumulation of organic and amino acids related to mitochondrial metabolism, especially when exposed to high glucose. Mitochondrial and metabolic defects down warding cell plasticity to adapt to changing glucose bioavailability may explain the comorbidity between iPD and T2DM.

Annexin A6 Is Critical to Maintain Glucose Homeostasis and Survival During Liver Regeneration in Mice.

BACKGROUND AND AIMS: Liver regeneration requires the organized and sequential activation of events that lead to restoration of hepatic mass. During this process, other vital liver functions need to be preserved, such as maintenance of blood glucose homeostasis, balancing the degradation of hepatic glycogen stores, and gluconeogenesis (GNG). Under metabolic stress, alanine is the main hepatic gluconeogenic substrate, and its availability is the rate-limiting step in this pathway. Na+ -coupled neutral amino acid transporters (SNATs) 2 and 4 are believed to facilitate hepatic alanine uptake. In previous studies, we demonstrated that a member of the Ca2+ -dependent phospholipid binding annexins, Annexin A6 (AnxA6), regulates membrane trafficking along endo- and exocytic pathways. Yet, although AnxA6 is abundantly expressed in the liver, its function in hepatic physiology remains unknown. In this study, we investigated the potential contribution of AnxA6 in liver regeneration. APPROACH AND RESULTS: Utilizing AnxA6 knockout mice (AnxA6-/- ), we challenged liver function after partial hepatectomy (PHx), inducing acute proliferative and metabolic stress. Biochemical and immunofluorescent approaches were used to dissect AnxA6-/- mice liver proliferation and energetic metabolism. Most strikingly, AnxA6-/- mice exhibited low survival after PHx. This was associated with an irreversible and progressive drop of blood glucose levels. Whereas exogenous glucose administration or restoration of hepatic AnxA6 expression rescued AnxA6-/- mice survival after PHx, the sustained hypoglycemia in partially hepatectomized AnxA6-/- mice was the consequence of an impaired alanine-dependent GNG in AnxA6-/- hepatocytes. Mechanistically, cytoplasmic SNAT4 failed to recycle to the sinusoidal plasma membrane of AnxA6-/- hepatocytes 48 hours after PHx, impairing alanine uptake and, consequently, glucose production. CONCLUSIONS: We conclude that the lack of AnxA6 compromises alanine-dependent GNG and liver regeneration in mice.

Effect of blood contamination of cerebrospinal fluid on amino acids, biogenic amines, pterins and vitamins.

BACKGROUND: Cerebrospinal fluid (CSF) metabolomic investigations are a powerful tool for studying neurometabolic diseases. We aimed to assess the effect of CSF contamination with blood on the concentrations of selected biomarkers. METHODS: CSF samples were spiked in duplicate with increasing volumes of whole blood under two conditions: (A) pooled CSF spiked with fresh whole blood and frozen to cause red blood cell (RBC) lysis; (B) pooled CSF spiked with fresh blood and centrifuged (the supernatant with no RBCs was frozen until the moment of analysis). CSF concentrations of amino acids, biogenic amines, pterins, and vitamins were analysed by HPLC coupled with tandem mass spectrometry, electrochemical and fluorescence detection. RESULTS: Aspartate, glutamate, taurine, ornithine, glycine, citrulline, pyridoxal 5´-phosphate, 5-methyltetrahydrofolate, and thiamine showed higher values when RBCs were lysed when compared with those of CSF with no RBC, while arginine, 5-hydroxyindoleacetic and homovanillic acids showed lower values. When RBCs were removed from CSF, only some amino acids, thiamine and pyridoxal 5´-phosphate showed moderately higher values when compared with the non-spiked CSF sample. CONCLUSIONS: CSF-targeted metabolomic analysis is feasible even when substantial RBC contamination of CSF has occurred since CSF centrifugation to remove RBC prior to freezing eliminated most of the interferences observed.

ADCK2 Haploinsufficiency Reduces Mitochondrial Lipid Oxidation and Causes Myopathy Associated with CoQ Deficiency.

Fatty acids and glucose are the main bioenergetic substrates in mammals. Impairment of mitochondrial fatty acid oxidation causes mitochondrial myopathy leading to decreased physical performance. Here, we report that haploinsufficiency of ADCK2, a member of the aarF domain-containing mitochondrial protein kinase family, in human is associated with liver dysfunction and severe mitochondrial myopathy with lipid droplets in skeletal muscle. In order to better understand the etiology of this rare disorder, we generated a heterozygous Adck2 knockout mouse model to perform in vivo and cellular studies using integrated analysis of physiological and omics data (transcriptomics-metabolomics). The data showed that Adck2+/- mice exhibited impaired fatty acid oxidation, liver dysfunction, and mitochondrial myopathy in skeletal muscle resulting in lower physical performance. Significant decrease in Coenzyme Q (CoQ) biosynthesis was observed and supplementation with CoQ partially rescued the phenotype both in the human subject and mouse model. These results indicate that ADCK2 is involved in organismal fatty acid metabolism and in CoQ biosynthesis in skeletal muscle. We propose that patients with isolated myopathies and myopathies involving lipid accumulation be tested for possible ADCK2 defect as they are likely to be responsive to CoQ supplementation.

Predicción de deterioro cognitivo en esquizofrenia: retrospectiva de 31 años / Prediction of cognitive damage in patient with schizophrenia: A thirty-one year retrospective

Este trabajo pretende averiguar qué subpruebas de la "Escala de inteligencia de Wechsler para adultos" (WAIS) forman el modelo cognitivo más parsimonioso capaz de predecir el importante deterioro cognitivo presentado por pacientes con esquizofrenia en edades avanzadas. Evaluamos con el "Mini-examen cognoscitivo" (MEC-35) a un grupo de 30 mujeres institucionalizadas diagnosticadas de esquizofrenia que 31 años antes habían sido valoradas con el WAIS. Encontramos que el 53,3% de las pacientes muestran deterioro significativo y 31 años antes puntuaciones más bajas en todas las pruebas del WAIS. Estas diferencias eran significativas (p< 0,05) en todas las medidas de cociente intelectual. A través del análisis de regresión logística encontramos que el modelo cognitivo que mejor predicción hizo lo forman las subpruebas de Semejanzas, Rompecabezas y Aritmética del WAIS, clasificando el 96,7% de los casos y presentando excelente validez de criterio con una sensibilidad del 93,8% y especificidad del 100%. Concluimos que el aumento de deterioro cognitivo en pacientes ancianas con esquizofrenia parece asociarse con una baja inteligencia fluida previa

The purpose of this study is to find out which tests from the Wechsler Intelligence Scale define the most detailed cognitive model that is able to predict the relevant cognitive impairment in elderly people with schizophrenia. A group of 30 institutionalised women who were diagnosed with schizophrenia were assessed with MEC-35; they had been previously assessed 31 years before using the WAIS. It was found that 53.3% of the patients showed significant cognitive impairment and 31 years ago their scores were lower in all the subtests from the WAIS. Those differences are significant (p< .05) in all of the IQ measurements. Throughout the logistical regression analysis we found that the cognitive model that made the best prediction was produced from the following subtests: Similarities, Puzzles and Arithmetic, classifying 96.7% of the cases and showing an excellent criterion validity, a sensitivity of 93.8% and a 100% of specificity. We conclude that the increase of the cognitive impairment in elderly patients with schizophrenia seems to be associated with previous low fluid intelligence

Autolesiones en una unidad de hospitalización psiquiátrica infanto-juvenil / Self-injury in a child and adolescent psychiatry inpatient unit

Introducción. La creciente prevalencia de conductas suicidas en adolescentes se ha convertido en un problema de salud pública. Existen varios factores asociados con este tipo de conductas: síntomas depresivos y ansiosos, consumo de sustancias, trastornos de conducta, violencia familiar, negligencia, abuso sexual en la infancia, etc. Con frecuencia, el comportamiento suicida se asocia a las autolesiones. Estas pueden definirse como conductas deliberadas destinadas a producir daño físico sin la intención de provocar la muerte. Método. Con la finalidad de estudiar el perfil clínico, las características y su comorbilidad con enfermedades psiquiátricas, hemos realizado un estudio observacional, descriptivo y con carácter prospectivo en los ingresados en la Unidad de Hospitalización Psiquiátrica Infanto Juvenil del Hospital Clínico Universitario de Valladolid durante el año 2016, que hayan presentado autolesiones. Entre las variables estudiadas: edad, sexo, procedencia, diagnóstico, abuso de sustancias, Autoinforme de evaluación funcional de la automutilación (FASM) e Inventario clínico para adolescentes Millon (MACI). Resultados. Durante el año 2016 hubo un total de 110 ingresos, de los cuales 27 (el 24,54%) han presentado autolesiones. En la mayoría de los casos (96,3%) se trata de pacientes de sexo femenino. Presentan alta comorbilidad, con trastorno de la conducta alimentaria (40,74%) y con trastorno por déficit de atención (29,63%). Conclusiones. La detección de estas conductas tiene importancia como señales de otra psicopatología que puede ser menos evidente. Dado que la edad de inicio de las mismas, en nuestro estudio, es los 11,81 años, habrá que prestar especial atención desde Pediatría de Atención Primaria

Introduction. The increasing prevalence of suicidal behavior in adolescents has become a public health problem. There are several factors associated with this type of behavior: depressive and anxious symptoms, substance use, behavioral disorders, family violence, neglect, sexual abuse in childhood... Suicidal behavior is often associated with self-harm. These can be defined as deliberate actions intended to cause physical harm without the intent of causing death. Method. In order to study the clinical profile, characteristics and their comorbidity with other psychiatric diseases, we carried out an observational, descriptive and prospective study in those patients who were admitted to the Child Psychiatric Unit of the Clinico Universitario Hospital of Valladolid during 2016, who have suffered self-harm. Among the variables studied were: age, sex, origin, diagnosis, substance abuse, FASM (self-report of functional evaluation of self-mutilation), and MACI (Millon Adolescents Clinical Inventory). Results. During the year 2016 there was a total of 110 admissions, of which, 27 (24.54%) had been self-injured The majority of cases (96.3%) are female patients. They present a high comorbidity with eating disorders (40.74%) and attention deficit disorder (29.63%). Conclusions. The detection of this behaviour is important as it may indicate the presence of other psychopathology that may be less evident. Given that the average age of onset in our study is 11.81 years old, it would be necessary for Primary Care Paediatrics to pay special attention to this

El reto del diagnóstico comórbido en psiquiatría infantojuvenil / The challenge of the comorbid diagnosis in childhood and adolescent psychiatry

Se presenta el caso de un paciente con fenotipo conductual cambiante y biotipo llamativo, con diagnóstico de trastorno por déficit de atención e hiperactividad (TDAH) desde la infancia y con respuesta parcial a los tratamientos pautados (metilfenidato de liberación prolongada, risperidona, sertralina). Tras un episodio de agresividad en el domicilio, ingresa en una unidad de hospitalización infantojuvenil y se objetivan alteraciones en la resonancia magnética nuclear (RMN) cerebral y en el estudio metabólico, siendo estas últimas compatibles con un déficit de ornitina transcarbamilasa (OTC), uno de los enzimas del ciclo de la urea. Se discuten los distintos diagnósticos planteados en vista del cuadro sindrómico del paciente, tanto a nivel orgánico como de una comorbilidad psiquiátrica. El déficit de OTC tiene una incidencia baja, de uno por cada 15.000 recién nacidos, similar a la de la fenilcetonuria (para la cual hay un programa establecido desde hace años de cribado neonatal). Se trata de una enfermedad predominantemente hereditaria (transmisión ligada al cromosoma X) pero con numerosos casos descritos de deleciones o mutaciones de novo. Un déficit completo inicia síntomas en los primeros años de vida, mientras que un déficit parcial podría comenzar en la infancia tardía o incluso en la adolescencia, con síntomas neuropsiquiátricos o conductuales inespecíficos, no existiendo descripción de un patrón claro

The case is presented of a patient with a changing behavioural phenotype and a rare biotype, who was diagnosed with attention deficit hyperactivity disorder (ADHD) from an early age, with partial response to the prescribed treatment (extended-release methylphenidate, risperidone, sertraline). After an aggressive episode at home, he was admitted to the child and adolescent hospitalisation unit. A brain NMR scan and a metabolic study revealed anomalies compatible with a deficiency of ornithine transcarbamylase (OTC), an enzyme which forms part of the urea cycle. The study discusses the different diagnoses that were proposed given the syndrome of the patient, both from an organic approach, as well as and from the perspective of psychiatric comorbidity. OTC deficiency has a low incidence -one in every 15,000 newborn babies-, similar to that of phenylketonuria (which was included years ago in the newborn screening program in Spain). This is a predominantly hereditary disease (X-linked transmission), but with several described cases of de novo mutations or deletions. Complete OTC deficiency shows its symptoms in the first years of life, whereas a partial deficiency could start during late childhood or even in adolescence, with unspecific neuropsychiatric or behavioural symptoms. A clear pattern has not been established

Gamma-aminobutyric acid levels in cerebrospinal fluid in neuropaediatric disorders.

AIM: Gamma-aminobutyric acid (GABA) is a major modulator in brain maturation and its role in many different neurodevelopmental disorders has been widely reported. Although the involvement of GABA in different disorders has been related to its regulatory function as an inhibitory neurotransmitter in the mature brain, co-transmitter, and signalling molecule, little is known about its role as a clinical biomarker in neuropaediatric disorders. The aim of this study is to report the cerebrospinal fluid (CSF) free-GABA concentrations in a large cohort of patients (n=85) with different neurological disorders. METHOD: GABA was measured in the CSF of neuropaediatric patients using capillary electrophoresis with laser-induced fluorescence detection. Other neurotransmitters (amino acids and monoamines) were also analysed. RESULTS: GABA concentrations in CSF were abnormal, with a greater frequency (44%) than monoamines (20%) in neuropaediatric patients compared with our reference values. Although we included a few patients with inborn errors of metabolism, GABA levels in CSF were more frequently abnormal in metabolic disorders than in other nosological groups. INTERPRETATION: Our work suggests further research into brain GABAergic status in neuropaediatric disorders, which could also lead to new therapeutic strategies. WHAT THIS PAPER ADDS: Homeostasis of GABA seems more vulnerable than that of monoamines in the developing brain. The highest GABA levels are found in the primary GABA neurotransmitter disorder SSADH deficiency. GABA alterations are not specific for any clinical or neuroimaging presentation.

A targeted metabolomic procedure for amino acid analysis in different biological specimens by ultra-high-performance liquid chromatography-tandem mass spectrometry.

INTRODUCTION: Amino acid analysis in biological fluids is essential for the study of inborn errors of metabolism (IEM) and other diseases. OBJECTIVES: Our aim was to develop a UPLC-MS/MS procedure for the analysis of 25 amino acids and identification of 17 related compounds. METHODS: Sample treatment conditions were optimized for plasma, urine, cerebrospinal fluid (CSF) and dried blood spots. Amino acids and related compounds were analyzed on a Waters ACQUITY UPLC H-class instrument with a reversed-phase C-18 column using water and acetonitrile with 0.1% formic acid as the mobile phases (run time = 9 min). The detection was performed with a Waters Xevo TQD triple-quadrupole mass spectrometer using positive electrospray ionization in the multiple reaction monitoring mode. RESULTS: The method linearity, intra-assay and inter-assay precision, detection limit, quantification limit and trueness analysis displayed adequate results in both physiological and pathological conditions. Method comparison was performed between UPLC-MS/MS and ion exchange chromatography (IEC) with ninhydrin derivatization, and the methods showed good agreement, except for 4-hydroxyproline, aspartate and citrulline. Paediatrics age-related reference values in plasma, urine and CSF were established and patients with different IEM were easily identified. CONCLUSION: We report a modified UPLC-MS/MS procedure for the analysis of 42 amino acids and related compounds in different specimens. The method is fast, sensitive and robust, and it has been validated to be an alternative to the traditional IEC procedure as the routine method used in metabolic laboratories. The method greatly decreases the run time of the analysis while displaying good metrological results.

Analysis of human cerebrospinal fluid monoamines and their cofactors by HPLC.

The presence of monoamines and their cofactors (the pterins and vitamin B6 (pyridoxal phosphate (PLP))) in human cerebrospinal fluid (CSF) can be used as indicators of the biosynthesis and turnover of dopamine and serotonin in the brain. In addition, abnormalities in the CSF levels of these molecules are associated with various neurological diseases, including genetic diseases leading to dopamine and serotonin deficiency. Here, we provide a set of quantitative high-performance liquid-chromatography (HPLC) approaches to determine CSF levels of monoamines and their cofactors. This protocol describes step-by-step procedures for CSF sample preparation for the analysis of different molecules, HPLC calibration and analysis, and data quantification and interpretation. Unlike plasma/tissue/blood samples, CSF requires minimal sample preparation: in this protocol, only the analysis of PLP requires mixing with trichloroacetic acid to release the protein-bound vitamin, centrifugation, and mixing of the supernatant with phosphate buffer and sodium cyanide for derivatization in alkaline conditions. Monoamines are analyzed by HPLC with coulometric electrochemical detection (ED), pterins are analyzed by HPLC with coupled coulometric electrochemical and fluorescence detection, and PLP is analyzed by HPLC with fluorescence detection. The quantification of all compounds is achieved by external calibration procedures, and internal quality control and standards are analyzed in each run. We anticipate that investigation of dopamine and serotonin disturbances will be facilitated by measurements of these compounds in human CSF and other biological samples. The estimated time for the different procedures primarily depends on the electrochemical detector stabilization. Overnight stabilization of this detector is advised, and, after that step, preanalytical equilibration rarely exceeds 3 h.

Correction: Natural Killer Cell Receptors and Cytotoxic Activity in Phosphomannomutase 2 Deficiency (PMM2-CDG).

[This corrects the article DOI: 10.1371/journal.pone.0158863.].

Natural Killer Cell Receptors and Cytotoxic Activity in Phosphomannomutase 2 Deficiency (PMM2-CDG).

BACKGROUND: PMM2-CDG is the most common N-glycosylation defect and shows an increased risk of recurrent and/or severe, sometimes fatal, infections in early life. We hypothesized that natural killer (NK) cells, as important mediators of the immune response against microbial pathogens and regulators of adaptive immunity, might be affected in this genetic disorder. OBJECTIVE: To evaluate possible defects on PMM2-CDG NK peripheral blood cell number, killing activity and expression of membrane receptors. METHODS: We studied fresh and activated NK cells from twelve PMM2-CDG cells. The number and expression of lymphoid surface receptors were studied by flow cytometry. The NK responsiveness (frequency of degranulated NK cells) and killing activity against K562 target cells was determined in the NK cytotoxicity assay. RESULTS: We found an increase of blood NK cells in three patients with a severe phenotype. Two of them, who had suffered from moderate/severe viral infections during their first year of life, also had reduced T lymphocyte numbers. Patient activated NK cells showed increased expression of CD54 adhesion molecule and NKG2D and NKp46 activating receptors. NKp46 and 2B4 expression was inversely correlated with the expression of NKG2D in activated PMM2-CDG cells. Maximal NK activity against K562 target cells was similar in control and PMM2-CDG cells. Interestingly, the NK cell responsiveness was higher in patient cells. NKG2D and specially CD54 increased surface expression significantly correlated with the increased NK cell cytolytic activity according to the modulation of the killer activity by expression of triggering receptors and adhesion molecules. CONCLUSIONS: Our results indicate that hypoglycosylation in PMM2-CDG altered NK cell reactivity against target cells and the expression of CD54 and NKG2D, NKp46 and 2B4 activating receptors during NK cell activation. This suggests a defective control of NK cell killing activity and the overall anti-viral immune response in PMM2-CDG patients. The present work improves our understanding of the immunological functions in PMM2-CDG and possibly in other CDG-I types.

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Inborn error metabolic screening in individuals with nonsyndromic autism spectrum disorders.

AIM: To perform metabolic testing on 406 patients (age range 3-22y [mean 6.71, SD 4.15], 343 males and 63 females) with nonsyndromic autism spectrum disorders (ASD) to assess the diagnostic yield. In addition, we reviewed our hospital's clinical database of 8500 patients who had undergone metabolic testing to be identified for inborn errors of metabolism (IEM), and described the characteristics of those with IEM and nonsyndromic ASD. METHOD: Neuropsychological evaluation included the Social Communication Questionnaire and Child Behavior Checklist. For metabolic testing/screening, urine samples were analyzed for the diagnosis of cerebral creatine deficiency syndromes, purine and pyrimidine disorders, amino acid metabolism defects, mucopolysaccharidoses, and organic acidurias. RESULTS: The 406 recruited participants fulfilled the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria of ASD. No biochemical evidence of a metabolic disorder was detected in any of the 406 patients studied. Concerning the retrospective evaluation from the 8500 who had metabolic testing, 464 individuals had a diagnosis of an IEM (394 without the diagnosis of ASD and 70 with ASD diagnosis). Only one individual with IEM had a diagnosis of nonsyndromic ASD at the time of the metabolic study; the metabolic testing had revealed diagnosis of urea-cycle disorder. INTERPRETATION: Metabolic testing should be considered in the work-up of individuals with syndromic ASD, but metabolic testing is not cost-effective for individuals with nonsyndromic ASD.