Metabolomics of urinary organic acids in respiratory chain deficiencies in children

Abstract

Metabolomic analysis of the urinary organic acids from 39 selected children with defined respiratory chain deficiencies (RCDs) was performed using untargeted gas chromatography-mass spectrometry, revealing the presence of 255 endogenous and 46 exogenous substances. Variable reduction identified 92 variables from the endogenous substances, which could be analysed by univariate and multivariate statistical methods. Using these methods, no characteristic organic acid biomarker profile could be defined of practical value for diagnostic purposes for complex I (CI), complex III (CIII) and multiple complex (CM) deficiencies. The statistical procedures used did, however, disclose 24 metabolites that were practical highly (d > 0.75) and statistically (p < 0.05) significant for the combined and clinically closely related group of RCDs. Several of these metabolites occur in single enzyme inherited metabolic diseases, but most were not previously reported to be linked to the metabolic perturbations that are due to RCDs. Ultimately, we constructed a global metabolic profile of carbohydrate, amino acid and fatty acid catabolism, illuminating the diverse and complex biochemical consequences of these disorders. This metabolomics investigation disclosed a metabolite profile that has the potential to define an 1 extended and characteristic biosignature for RCDs and the development of a non-invasive screening procedure for these disorders.

Qualitative serum organic acid profiles of HIV-infected individuals not on antiretroviral treatment

“…Many of these organic acids are highly specific markers used to detect neonatal inborn errors of metabolism (Pitt et al 2002). Organic acid analysis also proved valuable in our recent study that revealed a global profile of perturbations related to disorders of mitochondrial components (Reinecke et al 2011). These few examples indicate that organic acids are appropriate components of the metabolome for investigating the possible metabolic effects of HIV infection.…”

“…Organic acids were isolated from HIV-and HIV+ serum by solvent extraction prior to GC-MS analysis according to a published protocol (Reinecke et al 2011). All reagents used for organic acid extraction were from Merck (Darmstadt, Germany) unless otherwise stated.…”

“…All mass spectrometry was performed at the Centre for Human Metabonomics, North West University, Potchefstroom Campus, according to the protocol established there (Reinecke et al 2011). The dried residue was derivatized for 45 minutes at 70 °C using 40 µl N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA, Supelco Analytical, Bellefonte, USA), 8 µl trimethylchlorosilane (TMCS, Sigma-Aldrich) and 8 µl pyridine (Sigma-Aldrich).…”

Untargeted urine metabolomics reveals a biosignature for muscle respiratory chain deficiencies

“…One of these two values must be CS. Any deficient marker (CII or CIV) was excluded for interpretation and if both CII and CIV were deficient, only CS was used for identification b Clinical profile includes: Aid auto-immune disorder, BE behavior and emotional abnormalities, Car cardiac involvement, CNS central nervous system involvement, DD developmental delay, DR developmental regression, Dys dysmorphism (minor and major), E epilepsy, End endocrine abnormalities, ENT sensori-neural deafness, Eye vision involvement, G gastro-intestinal tract involvement, L liver involvement, M muscle involvement, PNS peripheral neuropathy, R renal involvement, S skeletal involvement, Skin Skin involvement c MDC score Mitochondrial Disease Score (Wolf and Smeitink 2002) described before (Smuts et al 2010, Reinecke et al 2012 were included in the RCD group and the patients with clinical features of a RCD but RC enzyme levels within the reference range were categorised to the CC group. Table 1 summarizes the characteristics of the selected experimental groups.…”

“…However, the control group used in this and related studies (Reinecke et al 2012) consisted of clinically healthy patients. This signature can therefore not be applied to limit the inclusion of false positive patients (i.e.…”