Treatment with vigabatrin may mimic alpha-aminoadipic aciduria

Purpose: We describe a secondary effect of treatment with vigabatrin (VGB). A significant increase in alpha-aminoadipic acid (AAA) occurred in plasma and urine of VGB-treated children, thus mimicking a known rare metabolic disease, alpha-aminoadipic aciduria (AAAuria). Methods: We studied eight children, aged from 3 months to 5 years, who were receiving VGB for drug-resistant partial epilepsies. Plasma and urine amino acids were assayed with ninhydrin detection on an automated Beckman 6300 analyzer. Results: In eight out of eight children, there was a significant increase of AAA in plasma and in urine. Plasma values ranged from 7 to 18 mu M (control values, <5) and urinary values from 67 to 274 mmol/mol creatinine (control values, <25). Conclusions: The concentrations of AAA in these VGB-treated children were as high as the concentrations found in the inherited metabolic disease, AAAuria. This could lead to incorrect diagnosis and to inappropriate genetic counseling. Thus whenever a genetic metabolic disease is suspected, amino acid chromatography testing should be performed before initiation of treatment with VGB.