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5122: Hepatic Histopathology in Urea Cycle Disorders


The purpose of this study is to review the medical records and obtain reports and discarded tissue from planned liver biopsies or liver transplants in individuals with a urea cycle disorder.

For Diseases

This study is for urea cycle disorders to include:

  • Argininosuccinate synthetase deficiency (ASS1D)
  • Argininosuccinate lyase deficiency (ASLD)
  • Arginase deficiency (ARG1D)
  • Ornithine transcarbamylase deficiency (OTCD)
  • Carbamyl phosphate synthetase 1 deficiency (CPS1D)
  • Citrullinemia type II (CITR) deficiency
  • N-acetylglutamate synthase deficiency (NAGSD)


Some patients with urea cycle disorders develop long-term liver disease with a buildup of scar tissue in the liver called fibrosis. This scar tissue can cause increased hardening of the liver tissue and cause damage to the liver. Some individuals with urea cycle disorders develop fat in the liver called steatosis and some develop enlargement of the liver. These abnormalities of the liver could potentially lead to increased risk for liver cancer.

It is difficult to study these complications without liver tissue from individuals with urea cycle disorders.

About this Study

If you decide to participate in the study, you will be asked to sign the informed consent form and answer a few questions to ensure that you are able to participate. There are no other procedures or information that we will collect from you. We will collect information from your medical records including results from your medical tests and liver biopsy or liver transplant. We will try to collect a sample of discarded tissue from your liver biopsy or liver transplant to study.

Target Enrollment

To be eligible to participate, the following criteria must be met:

Inclusion Criteria:

  • Diagnosis of primary urea cycle disorder based on clinical suspicion confirmed by enzyme activity, DNA testing or metabolite analyses of argininosuccinate synthetase deficiency (ASS1D), argininosuccinate lyase deficiency (ASLD), arginase deficiency (ARG1D), ornithine transcarbamylase deficiency (OTCD), carbamyl phosphate synthetase 1 deficiency (CPS1D), citrullinemia type II (CITR) deficiency, or N-acetylglutamate synthase deficiency (NAGSD)
  • Planned liver transplantation or liver biopsy

Exclusion Criteria:

  • Anticipated inability to obtain pathology report, liver tissue, tissue blocks, or pathology slides after liver biopsy or transplantation
  • Known history of a secondary cause for liver disease such as chronic viral hepatitis, autoimmune liver disease, short gut, small bowel syndrome, alcohol liver disease, or TPN-related cholestatic disease

How to participate

In order to participate in a study, you must personally contact the study coordinator of any of the participating institutions by phone or by e-mail. Please use the information to the right to inquire about participation.