Liver Disease in Urea Cycle Disorders

Urea cycle disorders (UCDs) are rare genetic conditions in which the liver cannot properly process nitrogen from protein breakdown, leading to dangerous ammonia buildup. Over time, even without dramatic ammonia crises, the liver can silently accumulate damage — scarring (fibrosis) and fat deposits — that has not been well studied. Understanding how the liver is affected in UCDs could lead to better monitoring and earlier treatment to prevent serious liver disease. This study conducts non-invasive liver assessments — including FibroScan (a special ultrasound) and MRI — in patients with four specific UCDs (OTCD, ASS1D, ASLD, ARG1D) to measure the degree of liver damage and fat. Data from these assessments will be compared to clinical factors like ammonia levels, diet, and medications to identify what predicts liver disease progression in this population. You may be eligible if: - You are between 6 and 65 years old - You weigh at least 11 kg - You have a molecular or biochemical diagnosis of OTCD, ASS1D, ASLD, or ARG1D You may NOT be eligible if: - You have previously had a liver transplant - You have had a severe ammonia episode (≥ 100 μmol/L) in the past 30 days - You have chronic viral hepatitis, autoimmune liver disease, or alcohol liver disease - You are currently pregnant - You have a cardiac pacemaker or implantable cardioverter-defibrillator - You have claustrophobia or metal implants preventing MRI (for Stage B) - Your BMI is ≥ 45 kg/m² (adults only) Talk to your doctor to see if this trial is right for you.