Abstract: Newborn screening for tyrosinemia type I (Tyr-I) is mandatory to identify infants at risk before life-threatening symptoms occur. The analysis of tyrosine alone is limited, and might lead to false-negative results. Consequently, the analysis of succinylacetone (SUAC) is needed. Current protocols are time-consuming, and above all, include hazardous reagents such hydrazine.
We evaluated a novel, commercial kit to analyze amino acids, acylcarnitines and SUAC with a significantly less harmful hydrazine derivative in a newborn screening laboratory. Dried blood spot specimens from 4683 newborns and samples from known patients with inborn errors of metabolism (IEM) were analyzed by a novel protocol and compared to an in-house screening assay. All samples were derivatized with butanol–HCl after extraction from 1/8-inch DBS punches.
For the novel protocol, the residual blood spots were extracted separately for SUAC, converted into hydrazone, combined with amino acids and acylcarnitines, and subsequently analyzed by mass spectrometry using internal isotope-labeled standards. All newborns were successfully tested, and 74 patients with IEMs including three with Tyr-I (SUAC 1.50, 4.80 and 6.49; tyrosine levels 93.10, 172.40 and 317.73, respectively) were detected accurately. The mean SUAC level in non-affected newborns was 0.68 μmol/l (cut-off 1.29 μmol/l). The novel assay was demonstrated to be accurate in the detection of newborns with IEM, robust, and above all, without the risk of the exposure to highly toxic reagents and requirement of additional equipment for toxic fume evacuation.
- Newborn screening for Tyr-I is mandatory before life-threatening symptoms occur.
- Current protocols are time-consuming, and include cancerogenic reagents.
- We evaluated a novel assay without the need of hazardous reagents.
Published in Clinica Chimica Acta; International Journal of Clinical Chemistry. Follow this link to read the full article.
Authors / corresponding author*
Thomas F. Metz*, a, b; Thomas P. Mechtler, a, b; Michael Merk, c; Anne Gottschalk, c; Richard Lukačin, c; Kurt R.Herkner, a,b;
David C. Kasper , a, b
a Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, Austria
b Research Core Unit of Pediatric Biochemistry and Analytics, Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Währinger Gürtel 18-20, Vienna, Austria
c Chromsystems Instrument & Chemicals GmbH, Am Haag 12, 82166 Gräfelfing/Munich, Germany