Identification of N-acetyl-alpha-aminoadipic acid in the urine of a patient with alpha-aminoadipic and alpha-ketoadipic aciduria.

A 3.5-year-old Japanese boy with a mild speech disturbance excreted a large amount of alpha-aminoadipic acid into the urine. The amino acid analysis using an amino acid analyser confirmed the presence of alpha-aminoadipic acid in both urine and plasma. We detected alpha-aminoadipic acid in the hydrolysate of the effluent and washwater fraction through cation exchange resin. This suggested the presence of acetylated derivatives and we identified N-acetyl-alpha-aminoadipic acid using liquid chromatography-atmospheric pressure ionization mass spectrometry (LC-API-MS). The concentrations of alpha-aminoadipic acid and N-acetyl-alpha-aminoadipic acid in the urine of a patient with alpha-aminoadipic aciduria were 376.9 nmol/mg creatinine and 18.1 nmol/mg creatinine, respectively. We also detected alpha-ketoadipic acid in the urine of this patient using LC-API-MS.