Lawrence Fisher1, Christine Davies2, Osama Y Al-Dirbashi3, Herman J Ten Brink4, Pranesh Chakraborty5, Nathalie Lepage6. 1. Newborn Screening Ontario, Children's Hospital of Eastern Ontario, 415 Smyth Road, Ottawa, Ontario, Canada. Electronic address: lfisher@cheo.on.ca. 2. Newborn Screening Ontario, Children's Hospital of Eastern Ontario, 415 Smyth Road, Ottawa, Ontario, Canada. 3. Newborn Screening Ontario, Children's Hospital of Eastern Ontario, 415 Smyth Road, Ottawa, Ontario, Canada; College of Medicine and Health Sciences, UAE University, Alain 17172, United Arab Emirates. 4. Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands. 5. Newborn Screening Ontario, Children's Hospital of Eastern Ontario, 415 Smyth Road, Ottawa, Ontario, Canada; Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada; University of Ottawa, Department of Pediatrics, 451 Smyth Road, Ottawa, Ontario, Canada; Better Outcomes Registry & Network "BORN Ontario", Canada. 6. Newborn Screening Ontario, Children's Hospital of Eastern Ontario, 415 Smyth Road, Ottawa, Ontario, Canada; Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada; University of Ottawa, Department of Pediatrics, 451 Smyth Road, Ottawa, Ontario, Canada; University of Ottawa, Department of Pathology and Laboratory Medicine, 451 Smyth Road, Ottawa, Ontario, Canada.
Abstract
BACKGROUND: Several acylcarnitines used as primary markers on dried blood filter papers (DBS) for newborn screening lack specificity and contribute to a higher false positive rate. The analysis of urine acylglycines is useful in the diagnosis of inborn errors of metabolism (IEM) including medium chain acyl-CoA dehydrogenase deficiency (MCADD), isovaleric acidemia, and beta-ketothiolase deficiency (BKTD). Currently, no method for analyzing acylglycines from DBS has been published. METHODS: Acylglycines were extracted from two 3.2 mm DBS punches and butylated using Butanol-HCl. Ultra Performance Liquid Chromatography (UPLC-MS/MS) with run time of 10 min permits resolution and quantitation of 15 acylglycines; including several isobaric. Method development was completed. Reference intervals (n = 573) were established for four birth weight groups. Furthermore, samples from patients with a confirmed IEM (n = 11), and false positive screens (n = 78) were analyzed to validate the interpretation obtained from the newly established reference intervals. RESULTS: Calibration curves were linear from 0.005 to 25.0 μM. Ion suppression was evaluated as minimal (2 to 10%). Samples from known patients were used to validate the reference intervals. For C5OH-related disorders, tiglylglycine (TG), TG/acetylglycine (AG) ratio, 3methylcrotonylglycine (3MCG) and 3MCG/AG ratio increased specificity. Propionylglycine (PG) and PG/acetylglycine ratio were two discriminatory markers in the investigation of C3-related disorders. Hexanoylglycine (HG), octanoylglycine (OG), suberylglycine (SG), and the ratios HG/AG, OC/AG and SG/AG were excellent markers of MCADD deficiency. CONCLUSION: This method shows potential application as a second tier screen in order to reduce the false positive rate for a number of IEM targeted by newborn screening.
BACKGROUND: Several acylcarnitines used as primary markers on dried blood filter papers (DBS) for newborn screening lack specificity and contribute to a higher false positive rate. The analysis of urine acylglycines is useful in the diagnosis of inborn errors of metabolism (IEM) including medium chain acyl-CoA dehydrogenase deficiency (MCADD), isovaleric acidemia, and beta-ketothiolase deficiency (BKTD). Currently, no method for analyzing acylglycines from DBS has been published. METHODS:Acylglycines were extracted from two 3.2 mm DBS punches and butylated using Butanol-HCl. Ultra Performance Liquid Chromatography (UPLC-MS/MS) with run time of 10 min permits resolution and quantitation of 15 acylglycines; including several isobaric. Method development was completed. Reference intervals (n = 573) were established for four birth weight groups. Furthermore, samples from patients with a confirmed IEM (n = 11), and false positive screens (n = 78) were analyzed to validate the interpretation obtained from the newly established reference intervals. RESULTS: Calibration curves were linear from 0.005 to 25.0 μM. Ion suppression was evaluated as minimal (2 to 10%). Samples from known patients were used to validate the reference intervals. For C5OH-related disorders, tiglylglycine (TG), TG/acetylglycine (AG) ratio, 3methylcrotonylglycine (3MCG) and 3MCG/AG ratio increased specificity. Propionylglycine (PG) and PG/acetylglycine ratio were two discriminatory markers in the investigation of C3-related disorders. Hexanoylglycine (HG), octanoylglycine (OG), suberylglycine (SG), and the ratios HG/AG, OC/AG and SG/AG were excellent markers of MCADD deficiency. CONCLUSION: This method shows potential application as a second tier screen in order to reduce the false positive rate for a number of IEM targeted by newborn screening.
Authors: Nicholas B Vera; Stephen L Coy; Evagelia C Laiakis; Albert J Fornace; Michelle Clasquin; Christopher A Barker; Jeffrey A Pfefferkorn; Paul Vouros Journal: J Am Soc Mass Spectrom Date: 2020-01-28 Impact factor: 3.109
Authors: Daniel J Wilkinson; Giovanny Rodriguez-Blanco; Warwick B Dunn; Bethan E Phillips; John P Williams; Paul L Greenhaff; Kenneth Smith; Iain J Gallagher; Philip J Atherton Journal: Aging (Albany NY) Date: 2020-06-24 Impact factor: 5.682