Mass Spectrometry-Based Metabolomic and Proteomic Strategies in Organic Acidemias

Organic acidemias (OAs) are inherited metabolic disorders caused by deficiency of enzymatic activities in the catabolism of amino acids, carbohydrates, or lipids. These disorders result in the accumulation of mono-, di-, or tricarboxylic acids, generally referred to as organic acids. The OA outcomes can involve different organs and/or systems. Some OA disorders are easily managed if promptly diagnosed and treated, whereas, in others cases, such as propionate metabolism-related OAs (propionic acidemia, PA; methylmalonic acidemia, MMA), neither diet, vitamin therapy, nor liver transplantation appears to prevent multiorgan impairment. Here, we review the recent developments in dissecting molecular bases of OAs by using integration of mass spectrometry-(MS-) based metabolomic and proteomic strategies. MS-based techniques have facilitated the rapid and economical evaluation of a broad spectrum of metabolites in various body fluids, also collected in small samples, like dried blood spots. This approach has enabled the timely diagnosis of OAs, thereby facilitating early therapeutic intervention. Besides providing an overview of MS-based approaches most frequently used to study the molecular mechanisms underlying OA pathophysiology, we discuss the principal challenges of metabolomic and proteomic applications to OAs

Mass Spectrometry-Based Metabolomic and Proteomic Strategies in Organic Acidemias,

Organic acidemias (OAs) are inherited metabolic disorders caused by deficiency of enzymatic activities in the catabolism of amino acids, carbohydrates, or lipids. These disorders result in the accumulation of mono-, di-, or tricarboxylic acids, generally referred to as organic acids. The OA outcomes can involve different organs and/or systems. Some OA disorders are easily managed if promptly diagnosed and treated, whereas, in others cases, such as propionate metabolism-related OAs (propionic acidemia, PA; methylmalonic acidemia, MMA), neither diet, vitamin therapy, nor liver transplantation appears to preventmultiorgan impairment. Here, we review the recent developments in dissecting molecular bases of OAs by using integration of mass spectrometry- (MS-) basedmetabolomic and proteomic strategies.MS-based techniques have facilitated the rapid and economical evaluation of a broad spectrumof metabolites in various body fluids, also collected in small samples, like dried blood spots. This approach has enabled the timely diagnosis of OAs, thereby facilitating early therapeutic intervention. Besides providing an overview ofMS-based approaches most frequently used to study the molecular mechanisms underlying OA pathophysiology, we discuss the principal challenges of metabolomic and proteomic applications to OAs

Mass Spectrometry-Based Metabolomic and Proteomic Strategies in Organic Acidemias

Organic acidemias (OAs) are inherited metabolic disorders caused by deficiency of enzymatic activities in the catabolism of amino acids, carbohydrates, or lipids. These disorders result in the accumulation of mono-, di-, or tricarboxylic acids, generally referred to as organic acids. The OA outcomes can involve different organs and/or systems. Some OA disorders are easily managed if promptly diagnosed and treated, whereas, in others cases, such as propionate metabolism-related OAs (propionic acidemia, PA; methylmalonic acidemia, MMA), neither diet, vitamin therapy, nor liver transplantation appears to prevent multiorgan impairment. Here, we review the recent developments in dissecting molecular bases of OAs by using integration of mass spectrometry- (MS-) based metabolomic and proteomic strategies. MS-based techniques have facilitated the rapid and economical evaluation of a broad spectrum of metabolites in various body fluids, also collected in small samples, like dried blood spots. This approach has enabled the timely diagnosis of OAs, thereby facilitating early therapeutic intervention. Besides providing an overview of MS-based approaches most frequently used to study the molecular mechanisms underlying OA pathophysiology, we discuss the principal challenges of metabolomic and proteomic applications to OAs

Female and male human babies have distinct blood metabolomic patterns

A sex-gender approach in laboratory medicine is scarce; furthermore, the influence of sex on acylcarnitines and amino acid levels at birth has not been thoroughly investigated, even if sex impacts on newborn screening. We aimed to establish the influence of sex on amino acids and acylcarnitines levels in male and female newborns. Amino acids and acylcarnitines were analysed in dried blood spots using tandem mass spectrometry in male and female newborns. Data were analysed before and after body weight correction also using principal components analysis. This retrospective analytical study showed that females had small but significantly higher levels of amino acids and the correction for body weight amplified these differences. Acylcarnitines were overall higher in males before body weight correction with the exception of isovalerylcarnitine + methylbutyrylcarnitine (C5), which was significantly higher in females. Body weight correction decreased the sex differences in C5. Principal component analysis showed that both amino acids and acylcarnitines were necessary to describe the model for females, whereas only acylcarnitines were required for males. These metabolomics data underline the importance of including sex as a variable in future investigations of circulating metabolites; the existence of sex differences highlights the need for setting distinct reference values for female and male neonates in metabolite concentration

Biochemical and molecular characterization of 3-Methylcrotonylglycinuria in an Italian asymptomatic girl

3-Methylcrotonylglycinuria is an organic aciduria resulting from deficiency of 3-methylcrotonyl-CoA carboxylase (3-MCC), a biotin-dependent mitochondrial enzyme carboxylating 3-methylcrotonil-CoA to 3-methylglutaconyl-CoA during leucine catabolism. Its deficiency, due to mutations on MCCC1 and MCCC2 genes, leads to accumulation in blood and/or urine of 3-hydroxyisovaleryl-carnitine (C5OH) in plasma and 3-methylcrotonyl-glycine and 3-hydroxyisovaleric acid in the urine. The phenotype of 3-MCC deficiency is highly variable, ranging from severe neurological abnormalities and death in infancy to asymptomatic adults. Here we report the biochemical and molecular characterization of an Italian asymptomatic female child, positive to the newborn screening, for which molecular analysis showed two severe mutations in MCCC2 gene, one missense mutation, c.691A>T (p.I231F), and one unknown splicing mutation, c.1150-1G>A. We characterized the expression profile of the novel splice mutation by functional studies

Data in support for the measurement of heparan sulfate and dermatan sulfate by LC–MS/MS analysis

This article provides supplementary data for the paper “LC–MS/MS method for simultaneous quantification of heparan sulfate and dermatan sulfate in urine by butanolysis derivatization” (Forni et al., 2018). Several parameters were tested to optimize sample preparation by butanolysis in order to carry out simultaneous quantifications of HS and DS by tandem mass spectrometry.Here we describe step-by-step instructions to perform HS and DS analysis in urine samples using external calibration curves of standards of known concentration. Sample are quantified by interpolation from the calibration curve and reported in µg/mL. Then, HS and DS are normalized to creatinine concentration and reported as mg/g uCr

The proteome of methylmalonic acidemia (MMA): elucidation of altered pathways in patient livers

Methylmalonic acidemia (MMA) is a heterogeneous and severe autosomal recessive inborn error of metabolism most commonly caused by the deficient activity of the vitamin B12 dependent enzyme, methylmalonyl-CoA mutase (MUT). The main treatment for MMA patients is the dietary restriction of propiogenic amino acids and carnitine supplementation. Despite treatment, the prognosis for vitamin B12 non-responsive patients remains poor and is associated with neonatal lethality, persistent morbidity and decreased life expectancy. While multi-organ pathology is a feature of MMA, the liver is severely impacted by mitochondrial dysfunction which likely underlies the metabolic instability experienced by the patients. Liver and/or combined liver/kidney transplantation is therefore sometimes performed in severely affected patients. Using liver specimens from donors and MMA patients undergoing elective liver transplantation collected under a dedicated natural history protocol (clinicaltrials.gov: NCT00078078), we employed proteomics to characterize the liver pathology and impaired hepatic metabolism observed in the patients. Pathway analysis revealed perturbations of enzymes involved in energy metabolism, gluconeogenesis and Krebs cycle anaplerosis. Our findings identify new pathophysiologic and therapeutic targets that could be valuable for designing alternative therapies to alleviate clinical manifestations seen in this disorder