NMR-based urinalysis for rapid diagnosis of inborn errors of metabolism

Abstract

AIMS: A rapid diagnosis for patients with suspected inborn errors of metabolism (IEM) is clinically important. However, most urine organic acid analysis (UOA) using GC-MS takes time. Here, we developed a rapid workflow using nuclear magnetic resonance (NMR) spectroscopy-based urinalysis as a complementary diagnostic tool to UOA. METHODS: Urine samples will be analysed using 1H-NMR spectroscopy, including 100 urine controls without IEM and urine samples from patients with beta-ketothiolase deficiency (BKD), beta-ureidopropionase deficiency (UPD), propionic acadaemia (PA), multiple carboxylase deficiency (MCD) and succinic semialdehyde dehydrogenase (SSADH) deficiency. A 2-dimension (1H-13C heteronuclear single quantum correlation, HSQC) will be performed to provide structural-based evidence on the positive identification of metabolites if necessary. RESULTS: Disease-specific markers were identified in all patients with IEM: butanone in BKD, β-ureidoisobutyric and β-ureidopropionic acids in UPD, 3-hydroxypropionic acid in PA, 3-hydroxyisovaleric acid in MCD, and 4-hydroxybutyric acid in SSADH deficiency, and they were not found in excess in unaffected controls. DISCUSSION: The operation of NMR is simple and fast; sample preparation is a 2-step procedure without the needs of derivatisation while a usual 1H-NMR acquisition takes <15 minutes. We envisage NMR analysis will play an essential role in acute paediatric care and will become more available in modern clinical laboratories.