Observational Study That Will Collect Information on Patients With Urea Cycle Disorders (UCDs)

UCDs disproportionately affect children and females: depending on the severity of the defect,
a UCD can manifest shortly after birth or later in life. This study will track long-term
outcomes in UCD patients and effects of ammonia-scavenging agents on neuropsychological
functions of UCD patients.

This is a non-interventional, multi-center registry to be conducted in patients with UCDs.
Investigators will prescribe treatments based on usual clinical practice, and there will be
no restrictions on the use of commercially available medications. As an observational study,
this study will not change the patient/ healthcare provider relationship, nor influence the
healthcare provider's drug prescription or the therapeutic management of the patient.

Patients with UCDs will be recruited and invited to attend a Baseline visit. After eligible
patients are enrolled, retrospective and baseline data will be collected. Patients will be
followed for up to 10 years, during which time they will be assessed by their healthcare
provider. Patients and healthcare provider will be asked to report episodes of hyperammonemic
crisis, available ammonia values, and other information.

Inclusion Criteria:

- Confirmed or suspected diagnosis of UCD

- Signed informed consent/Health Insurance Portability and Accountability Act (HIPAA)
Authorization and medical records release

Exclusion Criteria:

- Any other reason that, in the Investigator's opinion, makes the patient unsuitable to
participate in this study.