Systemic Biomarkers of Brain Injury From Hyperammonemia
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ClinicalTrials.gov Identifier: NCT04602325 |
Recruitment Status :
Recruiting
First Posted : October 26, 2020
Last Update Posted : November 1, 2021
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Ammonia is a waste product of protein and amino acid catabolism and is also a potent neurotoxin. High blood ammonia levels on the brain can manifest as cytotoxic brain edema and vascular compromise leading to intellectual and developmental disabilities. The following aims are proposed:
Aim 1 of this study will be to determine the chronology of biomarkers of brain injury in response to a hyperammonemic (HA) brain insult in patients with an inherited hyperammonemic disorder.
Aim 2 will be to determine if S100B, NSE, and UCHL1 are altered in patients with two other inborn errors of metabolism, Maple Syrup Urine Disease (MSUD) and Glutaric Acidemia (GA1).
Condition or disease |
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Urea Cycle Disorder Organic Acidemia Maple Syrup Urine Disease Glutaric Acidemia I Fatty Acid Oxidation Disorder Hypoxic-Ischemic Encephalopathy |
Ammonia is a waste product of protein and amino acid catabolism and is also a potent neurotoxin. The onslaught of high blood ammonia levels on the brain can manifest as cytotoxic brain edema and vascular compromise leading to intellectual and developmental disabilities. In addition, clinical hyperammonemia recurs at varying intervals, which can increase the cumulative damage to the brain and the chance of irreversible coma and death during a hyperammonemia episode due to vascular compromise or brain herniation. The threshold of tolerance for elevated blood ammonia is very low and concentrations above 100 µM can cause brain dysfunction manifested as nausea, vomiting, lethargy, and abnormal behavior; higher concentrations can cause coma and even death. Failure to remove ammonia can be due to inherited defects of the urea cycle, some defects in amino acid catabolism, and degradation of fatty acids.
Aim 1 - To determine the chronology of biomarkers of brain injury - S100B, NSE, and UCHL1 - in response to a hyperammonemic (HA) brain insult in patients with an inherited hyperammonemic disorder. We hypothesized that elevations of S100B, NSE, and UCHL1 will parallel the rise in blood ammonia. These biomarkers will be measured concurrently to ammonia levels throughout hospitalizations for HA until normalization of patient's blood ammonia and mental status.
Aim 2 - To determine if S100B, NSE, and UCHL1 are altered in patients with two other inborn errors of metabolism in which the primary pathology is neurological injury, Maple Syrup Urine Disease (MSUD) and Glutaric Acidemia (GA1). We hypothesize that neuronal and astroglial injury in these disorders may also result in increased levels of S100B, NSE, and UCHL1.
Metabolic patients will be enrolled either during a hospitalization or in outpatient clinic, but outpatient enrollment is preferred. Metabolic patients typically have multiple laboratory tests performed at their outpatient visits. We will obtain the discarded blood samples from such laboratory tests in order to measure S100B, NSE, and UCHL1 levels at baseline (normal blood ammonia), which will provide data on biomarker levels following recovery from a hyperammonemic episode.
During hospitalization for metabolic decompensation or for hypoxic-ischemic encephalopathy, sequential measurements of S100B, NSE and UCHL1 levels will be obtained from discarded blood samples. We will obtain S100B, NSE, and UCHL1 levels from collected discarded blood samples at all subjects' next outpatient visit following their hospitalization, to determine if levels return to baseline.
Study Type : | Observational |
Estimated Enrollment : | 24 participants |
Observational Model: | Cohort |
Time Perspective: | Prospective |
Official Title: | Systemic Biomarkers of Brain Injury From Hyperammonemia |
Actual Study Start Date : | July 9, 2020 |
Estimated Primary Completion Date : | July 2022 |
Estimated Study Completion Date : | May 2024 |

Group/Cohort |
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Inherited Hyperammonemias
A clinical diagnosis of 1 of 7 diagnosed urea cycle disorders:
A clinical diagnosis of 1 of 2 organic acidemias:
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Acute Metabolic Disorder + Neurological Sequelae
Acute metabolic disorder without hyperammonemia but with neurological sequelae:
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Fatty Acid Oxidation Disorders
Acute metabolic disorder without hyperammonemia and without neurological sequelae:
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Hypoxic-Ischemic Encephalopathy
Patients with hypoxic-ischemic encephalopathy
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- Biomarker Brain Injury Chronology [ Time Frame: 2 Years ]Determine the chronology of biomarkers of brain injury (S100B, NSE, and UCHL1) in response to a hyperammonemic (HA) brain insult in patients with an inherited hyperammonemic disorder
- Brain Injury Protein Alterations [ Time Frame: 2 Years ]Determine if S100B, NSE, and UCHL1 are altered in patients with two other inborn errors of metabolism in which the primary pathology is neurological injury, Maple Syrup Urine Disease (MSUD) and Glutaric Acidemia (GA1)
Biospecimen Retention: Samples Without DNA
Discarded blood samples will be obtained from such laboratory tests in order to measure S100B, NSE, and UCHL1 levels at baseline (normal blood ammonia), which will provide data on biomarker levels following recovery from a hyperammonemic episode.
During hospitalization for metabolic decompensation or for hypoxic-ischemic encephalopathy, sequential measurements of S100B, NSE and UCHL1 levels will be obtained from discarded blood samples.
S100B, NSE, and UCHL1 levels will again be obtained from collected discarded blood samples at all subjects' next outpatient visit following their hospitalization, to determine if levels return to baseline.

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Ages Eligible for Study: | 7 Years to 18 Years (Child, Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Sampling Method: | Non-Probability Sample |
Inclusion Criteria:
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Inherited Hyperammonemias:
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A clinical diagnosis of 1 of 7 diagnosed urea cycle disorders:
- N-acetylglutamate Synthetase Deficiency (NAGS)
- Carbamyl Phosphate Synthetase Deficiency (CPSD)
- Ornithine Transcarbamylase Deficiency (OTCD)
- Argininosuccinate Synthetase Deficiency (ASD)
- Argininosuccinate Lyase Deficiency (ALD)
- Arginase Deficiency (AD)
- Hyperammonemia-Hyperornithinemia-Homocitrullinuria (HHH)
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A clinical diagnosis of 1 of 2 organic acidemias:
- Propionic Acidemia (PA)
- Methylmalonic Acidemia (MMA)
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Acute metabolic disorder without hyperammonemia, with neurological sequelae
- Maple Syrup Urine Disease (MSUD)
- Glutaric Acidemia (GA1)
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Acute metabolic disorder without hyperammonemia and without neurological sequelae
- Fatty Acid Oxidation Disorders:
- Medium Chain-Acyl CoA Dehydrogenase Deficiency
- Very Long Chain-Acyl CoA Dehydrogenase Deficiency
- Trifunctional Protein Deficiency
- Long Chain Hydroxyacyl-CoA Dehydrogenase Deficiency
- Carnitine Palmitoyltransferase I or II Deficiency
- Carnitine/Acylcarnitine Translocase Deficiency
- Primary Carnitine Transport Deficiency
- Hypoxic-Ischemic Encephalopathy
Exclusion Criteria:
- Prior Solid-Organ Transplant
- Use of any other investigational drug, biologic, or therapy or any clinical or laboratory abnormality or medical condition that, as determined by the investigator, may interfere with or obscure the biomarker measurements

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04602325
Contact: Katie Rice, MPH, CCRP | 202-476-6191 | krice3@childrensnational.org | |
Contact: Nicholas Ah Mew, MD | 202-476-5863 | nahmew@childrensnational.org |
United States, District of Columbia | |
Children's National Research Institute | Recruiting |
Washington, District of Columbia, United States, 20010 | |
Contact: Katie Rice, MPH, CCRP krice3@childrensnational.org | |
Principal Investigator: Nicholas Ah Mew, MD |
Principal Investigator: | Nicholas Ah Mew, MD | Children's National Research Institute | |
Study Chair: | Ljubica Caldovic, PhD | Children's National Research Institute |
Responsible Party: | Nicholas Ah Mew, MD, Children's National Research Institute |
ClinicalTrials.gov Identifier: | NCT04602325 |
Other Study ID Numbers: |
14021 R21TR003166-01 ( U.S. NIH Grant/Contract ) |
First Posted: | October 26, 2020 Key Record Dates |
Last Update Posted: | November 1, 2021 |
Last Verified: | October 2021 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | Undecided |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
N-acetylglutamate Synthetase Deficiency Carbamyl Phosphate Synthetase Deficiency Ornithine Transcarbamylase Deficiency Argininosuccinate Synthetase Deficiency Argininosuccinate Lyase Deficiency Arginase Deficiency Hyperammonemia-Hyperornithinemia-Homocitrullinuria |
Medium Chain-Acyl CoA Dehydrogenase Deficiency Very Long Chain-Acyl CoA Dehydrogenase Deficiency Trifunctional Protein Deficiency Long Chain Hydroxyacyl-CoA Dehydrogenase Deficiency Carnitine Palmitoyltransferase I or II Deficiency Carnitine/Acylcarnitine Translocase Deficiency Primary Carnitine Transport Deficiency |
Brain Injuries Brain Diseases Brain Ischemia Hypoxia-Ischemia, Brain Urea Cycle Disorders, Inborn Maple Syrup Urine Disease Disease Hyperammonemia Pathologic Processes Central Nervous System Diseases Nervous System Diseases Craniocerebral Trauma Trauma, Nervous System |
Wounds and Injuries Hypoxia Signs and Symptoms, Respiratory Cerebrovascular Disorders Vascular Diseases Cardiovascular Diseases Hypoxia, Brain Brain Diseases, Metabolic, Inborn Brain Diseases, Metabolic Amino Acid Metabolism, Inborn Errors Metabolism, Inborn Errors Genetic Diseases, Inborn Metabolic Diseases |