Research Studies

Long-term observation of the impact of UCDs on physical and neurological functioning, the relationship between health indicators and disease severity and the efficiency of UCD therapies.

A post-marketing surveillance of carglumic acid (Carbaglu) to obtain long-term clinical safety information. Carglumic acid was approved by the United States Food and Drug Administration (FDA) for treatment of acute hyperammonemia due to N-acetylglutamate synthase (NAGS) deficiency.

Study of how UCDs affect thinking, body chemistry and brain structure using magnetic resonance imaging (MRI) and behavioral testing.

The purpose of this research is to determine if silent seizures (electrographic seizures) occur during a hyperammonemic (HA) episode in patients with urea cycle disorders (UCD). Urea cycle disorders lead to accumulation increased ammonia due to problems breaking down protein. The symptoms of UCD may present at birth, childhood or adulthood (milder deficiencies) and are associated with cognitive deficits, changes in behavior, brain swelling and seizures. Sometime the seizures are not clinically obvious, but can be picked up if a video recording and concurrent EEG (video EEG is used, cVEEG). cVEEG is used in many intensive care units across the country to pick up seizures. We want to determine if having seizures due to HA leads to any adverse cognitive outcomes, and want to use the EEG to identify any changes that may be associated with that.

The purpose of this study is to measure liver stiffness and chemicals in the blood that test liver injury and function in four urea cycle disorders. Sometimes the seizures are not clinically obvious, but can be picked up if a video recording and concurrent EEG (video EEG is used, cVEEG). cVEEG is used in many intensive care units across the country to pick up seizures. We want to determine if having seizures due to HA leads to any adverse cognitive outcomes, and want to use the EEG to identify any changes that may be associated with that.

We are doing this study to see how the results of two sets of tools used to measure developmental progress relate to one another and how acceptable completing each of these measures is to children and families of children with Urea Cycle Disorders. We are anxious to make longitudinal assessment (repeated observations over time) of cognition easier, quicker and more accessible for families of children with urea cycle disorders. In order to do so we want to understand the relationship between the 2 sets of measures.

The purpose of this research study is to test a new method to measure food intake using smart phone photos of your food before and after meals. We will compare the smart phone food photos to a 3-day diet record and we will measure how many calories you burn.

In this research study, Carbaglu was given to 5 patients with CPS1 deficiency and similar outcome measures were tested. Four patients demonstrated increased ureagenesis (urea production) and a decrease in the overall median ammonia levels with Carbaglu treatment (115 vs 82 μmol/L). One patient was given a longer-term trial of Carbaglu and had long-term stabilization of ammonia levels and was slowly weaned off of sodium phenylbutyrate. Future research will include identifying CPS1 mutations that may be responsive to NCG and a clinical trial of NCG in patients who experience acute hyperammonemia (high blood ammonia levels).

In this study, the investigators used mice with arginino-succinate lyase deficiency (ASLD) and cells from patients with ASLD to study the mechanisms involved in causing high blood pressure in this disorder, which is the second most common UCD (Figure 4). The investigators show that loss of the urea cycle enzyme ASL in the lining cells of the blood vessels leads to reduction of a chemical called nitric oxide (NO) and an increase in oxidative stress that lead to vascular dysfunction. Using data from a human trial that was funded by the Urea Cycle Disorders Consortium (UCDC), they also show that the blood pressure in individuals with ASLD can be elevated.