Diagnosing AICA-ribosiduria by capillary electrophoresis

AICA-ribosiduria is a recently discovered inherited metabolic disease caused by a defect in final steps of purine de novo biosynthesis—5-amino-4-imidazolecarboxamide ribotide (AICAR)-transformylase/inosinemonophosphate (IMP)-cyclohydrolase (ATIC). A rapid and selective capillary electrophoretic method for screening of patients with AICA-ribosiduria is described. The method is based on direct ultraviolet detection of 5-amino-4-imidazolecarboxamide (AICA) and 5-amino-4-imidazolecarboxamide riboside (AICAr) in untreated urine. Background electrolyte consists of 100 mM malonic acid adjusted with γ-aminobutyric acid (pH 2.7). Under the given separation conditions both compounds of interest are well separated from other substances with separation efficiency of 1 020 000 and 130 000 theoretical plates/m for AICA and AICAr, respectively. Total analysis time is 3 min with the limits of detection of 3.6 μM and 4.5 μM for AICA and AICAr, respectively. The usefulness of the presented method for screening of patients with ATIC deficiency is demonstrated on samples of Chinese hamster ovary cell line defective in ATIC activity, spiked urine samples and urine samples from patients treated with high-dose MTX which do not excrete increased amounts of AICA and AICAr compared to untreated controls (p < 0.05). The described method is fast and effective enough for diagnostic applications.