Diagnosis of glutaric aciduria type 1 by measuring 3-hydroxyglutaric acid in dried urine spots by liquid chromatography tandem mass spectrometry.
Accumulation of glutaric acid (GA) and 3-hydroxyglutaric acid (3HGA) in body fluids is the biochemical hallmark of type 1 glutaric aciduria (GA1), a disorder characterized by acute striatal degeneration and a subsequent dystonia. To date, methods for quantification of 3HGA are mainly based on stable isotope dilution gas chromatography mass spectrometry (GC-MS) and require extensive sample preparation. Here we describe a simple liquid chromatography tandem MS (LC-MS/MS) method to quantify this important metabolite in dried urine spots (DUS). This method is based on derivatization with 4-[2-(N,N-dimethylamino)ethylaminosulfonyl]-7-(2-aminoethylamino)-2,1,3-benzoxadiazole (DAABD-AE). Derivatization was adopted to improve the chromatographic and mass spectrometric properties of the studied analytes. Derivatization was performed directly on a 3.2-mm disc of DUS as a sample without extraction. Sample mixture was heated at 60°C for 45 min, and 5 μl of the reaction solution was analyzed by LC-MS/MS. Reference ranges obtained were in excellent agreement with the literature. The method was applied retrospectively for the analysis of DUS samples from established low- and high-excreter GA1 patients as well as controls (n = 100). Comparison of results obtained versus those obtained by GC-MS was satisfactory (n = 14). In populations with a high risk of GA1, this approach will be useful as a primary screening method for high- or low-excreter variants. In these populations, however, DUS analysis should not be implemented before completing a parallel comparative study with the standard screening method (i.e., molecular testing). In addition, follow-up DUS GA and 3HGA testing of babies with elevated dried blood spot C5DC acylcarnitines will be useful as a first-tier diagnostic test, thus reducing the number of cases requiring enzymatic and molecular analyses to establish or refute the diagnosis of GA1.
Al-Dirbashi
Osama Y
OY
Newborn Screening Ontario, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada.
Kölker
Stefan
S
Ng
Dione
D
Fisher
Lawrence
L
Rupar
Tony
T
Lepage
Nathalie
N
Rashed
Mohamed S
MS
Santa
Tomofumi
T
Goodman
Stephen I
SI
Geraghty
Michael T
MT
Zschocke
Johannes
J
Christensen
Ernst
E
Hoffmann
Georg F
GF
Chakraborty
Pranesh
P
D000592:Amino Acid Metabolism, Inborn Errors / Q000175:diagnosis / Q000652:urine; D001928:Brain Diseases, Metabolic / Q000175:diagnosis / Q000652:urine; D002853:Chromatography, Liquid / Q000379:methods; D003890:Desiccation; D005977:Glutarates / Q000032:analysis / Q000652:urine*; D050770:Glutaryl-CoA Dehydrogenase / Q000172:deficiency / Q000652:urine; D006801:Humans; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
C108959:3-hydroxyglutaric acid; D005977:Glutarates; D050770:Glutaryl-CoA Dehydrogenase