Long Term Follow Up to Evaluate DTX301 in Adults With Late-Onset OTC Deficiency

Inclusion Criteria: 1. Completed the Week 52 visit in Study 301OTC01. 2. Willing and able to provide written informed consent. 3. Willing, able, and committed to comply with scheduled study site visits, study procedures, and requirements. Exclusion Criteria: 1. Planned or current participation in another interventional clinical study that may confound the efficacy or safety evaluation of DTX301 during the duration of this study. 2. Any clinically significant medical condition that, in the opinion of the investigator, would pose a risk to subject safety or would impede the study.