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Citrullinemia type I

The second urea cycle disorder indication to be targeted by Evox is Citrullinemia type I, which is caused by a mutation in the ASS1 gene leading to a deficiency in hepatic enzyme arginosuccinate synthetase (ASS) that results in high levels of citrulline and ammonia in the blood.



Newborn patients with a profound lack of ASS enzyme activity can suffer severe neurological consequences and the disease can be fatal if untreated. A milder form of the disorder, which is characterized by partial lack of the ASS enzyme, may occur later during infancy or childhood. Citrullinemia type I has an estimated worldwide incidence of roughly 1 in 57,000 live births.

Despite disease management strategies (dietary restrictions and ammonia scavengers), mortality in Citrullinemia type I patients is approximately 15% and there is need for disease modifying therapies.