Influence of glutamine synthetase gene polymorphisms on the development of hyperammonemia during valproic acid-based therapy

Phenytoin coadministration, GLUL rs10797771 polymorphism in the 200 μg/dL cutoff value, and female in addition to two factors in the 170 μg/dL cutoff value, are independent risk factors for elevated plasma ammonia levels during VPA-based therapy.