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.

Dysregulated Cell Homeostasis and miRNAs in Human iPSC-Derived Cardiomyocytes from a Propionic Acidemia Patient with Cardiomyopathy.

Propionic acidemia (PA) disorder shows major involvement of the heart, among other alterations. A significant number of PA patients develop cardiac complications, and available evidence suggests that this cardiac dysfunction is driven mainly by the accumulation of toxic metabolites. To contribute to the elucidation of the mechanistic basis underlying this dysfunction, we have successfully generated cardiomyocytes through the differentiation of induced pluripotent stem cells (iPSCs) from a PCCB patient and its isogenic control.

Neuropathological Findings in Short-Chain enoyl-CoA Hydratase 1 Deficiency (ECHS1D): Case Report and Differential Diagnosis.

Short-chain enoyl-CoA hydratase 1 (ECHS1) is an enzyme that participates in the metabolism of valine, transforming methacrylyl-CoA in β-hydroxy-isobutyryl-CoA. There is an accumulation of intermediate acids and ammonium as a consequence of its deficit. This background generates a harmful environment for the brain causing neuronal death and severe brain lesions.

Novel variants in GALE cause syndromic macrothrombocytopenia by disrupting glycosylation and thrombopoiesis.

Glycosylation is recognized as a key process for proper megakaryopoiesis and platelet formation. The enzyme uridine diphosphate (UDP)-galactose-4-epimerase, encoded by GALE, is involved in galactose metabolism and protein glycosylation. Here, we studied 3 patients from 2 unrelated families who showed lifelong severe thrombocytopenia, bleeding diathesis, mental retardation, mitral valve prolapse, and jaundice.

Newborn screening for propionic, methylmalonic acidemia and vitamin B12 deficiency. Analysis of 588,793 newborns.

Objectives: We present the results of our experience in the diagnosis and follow up of the positive cases for propionic, methylmalonic acidemias and cobalamin deficiencies (PA/MMA/MMAHC) since the Expanded Newborn Screening was implemented in Madrid Region.

Methods: Dried blood samples were collected 48 h after birth. Amino acids and acylcarnitines were quantitated by MS/MS.

Lymphocyte Medium-Chain Acyl-CoA Dehydrogenase Activity and Its Potential as a Diagnostic Confirmation Tool in Newborn Screening Cases.

The determination of acylcarnitines (AC) in dried blood spots (DBS) by tandem mass spectrometry in newborn screening (NBS) programs has enabled medium-chain acyl-coA dehydrogenase deficiency (MCADD) to be identified in presymptomatic newborns. Nevertheless, different confirmatory tests must be performed to confirm the diagnosis. In this work, we have collected and analyzed the NBS results and confirmatory test results (plasma AC, molecular findings, and lymphocyte MCAD activity) of forty individuals, correlating them with clinical outcomes and treatment, with the aim of obtaining useful diagnostic information that could be applied in the follow-up of the patients.

Technical Aspects of Coenzyme Q Analysis: Validation of a New HPLC-ED Method.

The biochemical measurement of the CoQ status in different tissues can be performed using HPLC with electrochemical detection (ED). Because the production of the electrochemical cells used with the Coulochem series detectors was discontinued, we aimed to standardize a new HPLC-ED method with new equipment. We report all technical aspects, troubleshooting and its performance in different biological samples, including plasma, skeletal muscle homogenates, urine and cultured skin fibroblasts.

Biochemical Markers for the Diagnosis of Mitochondrial Fatty Acid Oxidation Diseases.

Mitochondrial fatty acid β-oxidation (FAO) contributes a large proportion to the body's energy needs in fasting and in situations of metabolic stress. Most tissues use energy from fatty acids, particularly the heart, skeletal muscle and the liver. In the brain, ketone bodies formed from FAO in the liver are used as the main source of energy.

Long-term follow-up with filter paper samples in patients with propionic acidemia.

Background: Propionic acidemia (PA) is an inherited disorder caused by deficiency of propionyl CoA carboxylase. Most patients with this disorder are diagnosed during the neonatal period because of severe metabolic acidosis and hyperammonemia. Patients are required to undergo blood and urine analysis at least 3 to 4 times per year, depending on age and metabolic control.

Metabolic Serendipities of Expanded Newborn Screening.

Incidental findings on newborn screening (NBS) are results that are not the target of screening within a given NBS program, but rather are found as a result of the screening and resulting diagnostic workup for that target. These findings may not have an immediate clinical impact on the newborn, but are sometimes an additional benefit of NBS programs and may be considered secondary targets of NBS programs. This work describes four case reports that had incidental findings on the NBS, which eventually led to the diagnosis of another metabolic disease instead of the one that was initially suspected.

Genes and Variants Underlying Human Congenital Lactic Acidosis-From Genetics to Personalized Treatment.

Congenital lactic acidosis (CLA) is a rare condition in most instances due to a range of inborn errors of metabolism that result in defective mitochondrial function. Even though the implementation of next generation sequencing has been rapid, the diagnosis rate for this highly heterogeneous allelic condition remains low. The present work reports our group's experience of using a clinical/biochemical analysis system in conjunction with genetic findings that facilitates the taking of timely clinical decisions with minimum need for invasive procedures.

Two novel mutations in the BCKDK (branched-chain keto-acid dehydrogenase kinase) gene are responsible for a neurobehavioral deficit in two pediatric unrelated patients.

Inactivating mutations in the BCKDK gene, which codes for the kinase responsible for the negative regulation of the branched-chain α-keto acid dehydrogenase complex (BCKD), have recently been associated with a form of autism in three families. In this work, two novel exonic BCKDK mutations, c.520C>G/p.

Determination of urinary alpha-aminoadipic semialdehyde by LC-MS/MS in patients with congenital metabolic diseases.

This paper describes a full detailed high performance liquid chromatography/tandem mass spectrometry method for the identification and quantification of human urine alpha-aminoadipic semialdehyde, biomarker of pyridoxine-dependent epilepsy. The ionization mode of the electrospray interface was negative and the metabolite was detected in the multiple reaction monitoring mode. Intra-day and inter-day laboratory precision were 4.

Clinical, biochemical, and molecular studies in pyridoxine-dependent epilepsy. Antisense therapy as possible new therapeutic option.

Purpose: Pyridoxine-dependent epilepsy seizure (PDE; OMIM 266100) is a disorder associated with severe seizures that can be controlled pharmacologically with pyridoxine. In the majority of patients with PDE, the disorder is caused by the deficient activity of the enzyme α-aminoadipic semialdehyde dehydrogenase (antiquitin protein), which is encoded by the ALDH7A1 gene. The aim of this work was the clinical, biochemical, and genetic analysis of 12 unrelated patients, mostly from Spain, in an attempt to provide further valuable data regarding the wide clinical, biochemical, and genetic spectrum of the disease.

A novel congenital disorder of glycosylation type without central nervous system involvement caused by mutations in the phosphoglucomutase 1 gene.

Recent years have seen great advances in our knowledge of congenital disorders of glycosylation (CDG), a clinically and biochemically heterogeneous group of genetic diseases caused by defects in the synthesis (CDG-I) or processing (CDG-II) of glycans that form glycoconjugates. This paper reports a new subtype of non-neurological CDG involving the impaired cytoplasmic biosynthesis of nucleotide sugars needed for glycan biosynthesis. A patient presented with muscle fatigue, elevated creatine kinase, growth hormone deficiency, and first branchial arch syndrome.

Defining the pathogenicity of creatine deficiency syndrome.

This work examined nine patients with creatine deficiency syndrome (CDS): six with a creatine transport (CRTR) defect and three with a GAMT defect. Eleven nucleotide variations were detected: six in SLC6A8 and five in GAMT. These changes were analyzed at the mRNA level and specific alleles (most of which bore premature stop codons) were selected as nulls because they provoked nonsense-mediated decay activation.

Marked mitochondrial DNA depletion associated with a novel SUCLG1 gene mutation resulting in lethal neonatal acidosis, multi-organ failure, and interrupted aortic arch.

The aim of this study was to identify the causative genetic lesion in two apparently unrelated newborns having lethal lactic acidosis, multi-organ failure and congenital malformations including interrupted aortic arch, who exhibited mild methylmalonic aciduria, combined mitochondrial respiratory chain deficiency, and marked muscle mitochondrial DNA depletion. A novel mutation in the SUCLG1 gene was identified. Phenotype severity in Succinate-CoA ligase dysfunction appears to be more correlated to the muscle mtDNA content than to the tissue distribution of the heterodimer subunits.

Separation and identification of plasma short-chain acylcarnitine isomers by HPLC/MS/MS for the differential diagnosis of fatty acid oxidation defects and organic acidemias.

This paper reports a new, high-performance liquid chromatography/tandem mass spectrometry method for the separation and identification of human plasma short-chain acylcarnitine isomers. This simple, rapid procedure involves the use of a single sample previously shown to contain elevated acylcarnitine concentrations by flow injection analysis, and can separate two C4, three C5, two C5:1 and four C5-OH acylcarnitine isomers, thus permitting the differential diagnosis of certain fatty acid oxidation defects and organic acidemias.