Methods of assessing the efficacy of an agent in treating a disease or disorder are provided that include determining whether the agent causes, or inhibits, direct or indirect recruitment and/or ubiquitination and/or degradation of argininosuccinate synthetase 1 (ASS1).

Compositions and regimens useful in treating type I citrullenemia are provided. The compositions include recombinant adeno-associated virus (rAAV) with a transthyretin enhancer and promoter driving expression of a human Argininosuccinate Synthase 1 (ASS1).