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Measurement of carnitine and acylcarnitines in plasma is important in diagnosis of fatty acid β-oxidation disorders and organic acidemia. The usual method uses flow injection tandem mass spectrometry (FIA-MS/MS), which has limitations. A rapid and more accurate method was developed to be used for high-risk screening and diagnosis. Carnitine and acylcarnitines were separated by hydrophilic interaction liquid chromatography (HILIC) without derivatization and detected with a QTRAP MS/MS System. Total analysis time was 9.0min. The imprecision of within- and between-run were less than 6% and 17%, respectively. Recoveries were in the range of 85-110% at three concentrations. Some acylcarnitine isomers could be separated, such as dicarboxylic and hydroxyl acylcarnitines. The method could also separate interferent to avoid false positive results. 216 normal samples and 116 patient samples were detected with the validated method, and 49 patients were identified with fatty acid oxidation disorders or organic acidemias., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Free carnitine (C0) and short chain acylcarnitine (SCA) blood concentrations play a significant role in fatty acid oxidation process during the first days of life. The aim of this study was to demonstrate C0 and SCA concentrations in Dried Blood Spots (DBS) of full term breastfed infants in relation to their birth weight (BW) perinatally. Breastfed full term infants (n = 12,000, 6000 males, 6000 females) with BW 2000–4000 g were divided into 4 equal groups: Group A, 2000–2500 g, B 2500–3000 g, C 3000–3500 g and D 3500–4000 g. Blood samples in the form of DBS were collected on the 3rd day of life and analyzed via a liquid chromatography tandem mass spectrometry (LC-MS/MS) protocol. BW-related C0 and SCAs were found as follows: C0 was determined to be statistically significantly higher in group A (BW 2000–2500 g) in both males and females. Lower acetylcarnitine (C2) and hydroxybutyrylcarnitine (C4OH) blood concentrations were detected in group A of both sexes, whereas butyrylcarnitine (C4) concentrations were found to be lower in the same group of males only. Furthermore, high concentrations of C2 and C4OH were shown in group D (BW 3500–4000 g) in both sexes. SCA sum of means ± SD values in males and females of group A were statistically significantly lower as compared to other study groups. Due to the number of the samples, data from this study could be applied as neonatal screening reference values for full term breastfed newborns in relation to their birth weight. [ABSTRACT FROM AUTHOR]

Propionic acidemia (PA) is a disorder of organic acid metabolism which typically presents with acute encephalopathy-like symptoms associated with metabolic acidosis and hyperammonemia during the neonatal period. The estimated incidence of symptomatic PA in Japan is 1/400,000. The introduction of neonatal screening using tandem mass spectrometry has revealed a far higher disease frequency of approximately 1/45,000 live births due to a prevalent variant of c.1304T>C (p.Y435C) in PCCB, which codes β-subunit of propionyl-CoA carboxylase. Our questionnaire-based follow-up study reveals that most of these patients remain asymptomatic. However, reports on symptomatic patients exhibiting cardiac complications such as cardiomyopathy and QT prolongation have been increasing. Moreover, there were even cases in which these cardiac complications were the only symptoms related to PA. A currently ongoing study is investigating the risk of cardiac complications in patients with neonatal screening-detected PA caused by this common variant.

Background: Biotinidase deficiency is a treatable metabolic disease that can be seen with various neurological and dermatological complications. Biomarkers such as alanine, propionylcarnitine (C3) and 3-hydroxyisovalerylcarnitine (C5-OH), which are used to diagnose biotinidase deficiency, are also present. Materials and methods: In cases with partial biotinidase deficiency and normal biotinidase activity, alanine, C3 and C5-OH levels were compared in the field by liquid chromatography-tandem mass spectrometry. Results: There was no significant difference between subjects with partial biotinidase deficiency and those with normal biotinidase activity between C3 and C5-OH levels. The mean alanine levels in heel blood and plasma were significantly higher than those with normal biotinidase activity in patients with partial biotinidase deficiency. Conclusion: In cases with partial biotinidase deficiency, the heel blood alanine level that can be detected in the neonatal screening program may be a leading marker in diagnosis. [ABSTRACT FROM AUTHOR]

Background: Propionic acidemia (PA) is a serious metabolic disorder, and different approaches have been applied to its prenatal diagnosis. To evaluate the reliability and validity of a biochemical strategy in the prenatal diagnosis of PA, we conducted a retrospective study of our 11-year experiences at a single center.Methods: We accumulated data from 78 pregnancies from 58 families referred to our center and provided prenatal diagnosis by directed genetic analysis and/or metabolite measurement using tandem mass spectrometry (MS/MS) and gas chromatography/mass spectrometry (GC/MS) of amniotic fluid (AF) samples.Results: Sixty-five unaffected fetuses (83.33%) and 13 affected fetuses (16.67%) were confirmed in our study. The characteristic metabolites including propionylcarnitine (C3) level, C3/acetylcarnitine (C2) ratio and 2-methylcitric acid (2MCA) level in unaffected and affected groups showed significant differences (P < 0.0001), while the level of 3-hydroxypropionic acid (3HPA) showed no significant difference between the two groups (P > 0.05).Of the 78 pregnancies, 24 fetuses were found to have either one causative pathogenic variant or were without genetic information in the proband. Three of these fetuses had elevated AF levels of C3, C3/C2 ratio, and 2MCA and, thus, were determined to be affected, while the remaining fetuses were determined to be unaffected based on a normal AF metabolite profile. Our genetic and biochemical results were highly consistent with postnatal follow-up results on all unaffected fetuses.Conclusions: We conclude that a biochemical approach can serve as a fast and convenient prenatal diagnostic method for pregnancies at an increased risk for PA, which could be used in conjunction with genetic testing for precise prenatal diagnosis of this disorder. In our analysis, the characteristic metabolites C3 level, C3/C2 ratio, and 2MCA level in AF supernatant were dependable biochemical markers for diagnosis, of which the C3/C2 ratio appears to be the most reliable biochemical marker for the prenatal diagnosis of PA. [ABSTRACT FROM AUTHOR]