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Questions about rare diseases?
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Disease at a Glance

Summary
Carbamoyl phosphate synthetase I deficiency (CPS1 deficiency) is a genetic disorder that causes episodes of toxic levels of ammonia in the blood (hyperammonemia). Symptoms include poor feeding, vomiting, lack of energy, low body temperature and weak muscle tone. These usually occur in the first few days of life. High levels of ammonia can lead to complications such as seizures, breathing problems, intellectual disability and coma. CPS1 deficiency is caused by alterations in the CPS1 gene and is inherited in an autosomal recessive pattern. Diagnosis is based on symptoms, laboratory testing, and genetic testing.
Summary
Carbamoyl phosphate synthetase I deficiency (CPS1 deficiency) is a genetic disorder that causes episodes of toxic levels of ammonia in the blood (hyperammonemia). Symptoms include poor feeding, vomiting, lack of energy, low body temperature and weak muscle tone. These usually occur in the first few days of life. High levels of ammonia can lead to complications such as seizures, breathing problems, intellectual disability and coma. CPS1 deficiency is caused by alterations in the CPS1 gene and is inherited in an autosomal recessive pattern. Diagnosis is based on symptoms, laboratory testing, and genetic testing.Carbamoyl phosphate synthetase I deficiency (CPS1 deficiency) is a genetic disorder that causes episodes of toxic levels of ammonia in the blood (hyperammonemia). Symptoms include poor feeding, vomiting, lack of energy, low body temperature and weak muscle tone. These usually occur in the first few days of life. High levels of ammonia can lead to complications such as seizures, breathing problems, intellectual disability and coma. CPS1 deficiency is caused by alterations in the CPS1 gene and is inherited in an autosomal recessive pattern. Diagnosis is based on symptoms, laboratory testing, and genetic testing.
Resource(s) for Medical Professionals and Scientists on This Disease:
  • Orphanet  provides GARD with information for this disease.
  • RARe-SOURCE™  offers rare disease gene variant annotations and links to rare disease gene literature.
  • GeneReviews  provides scientific information on genetic diseases, including diagnosis, treatment, and genetic counseling.

About Carbamoyl-phosphate synthetase 1 deficiency

Many rare diseases have limited information. Currently GARD aims to provide the following information for this disease:

  • Population Estimate:Fewer than 5,000 people in the U.S. have thisdisease.
  • Symptoms:May start to appear at any time in life.
  • Cause:This disease is caused by a change in the genetic material (DNA).
  • Organizations:Patient organizations are available to help find a specialist, or advocacy and support for this specific disease.
  • Newborn Screening:This disease may be detected through routine newbornscreening.
  • Categories:Inherited Metabolic DiseasesGenetic Diseases
When Do Symptoms of Carbamoyl-phosphate synthetase 1 deficiency Begin?
Symptoms of this disease may start to appear at any time in life.

The age symptoms may begin to appear differs between diseases. Symptoms may begin in a single age range, or during several age ranges. The symptoms from some diseases may begin at any age. Knowing when symptoms began to appear can help medical providers find the correct diagnosis.
Prenatal Selected
Before Birth
Newborn Selected
Birth-4 weeks
Infant Selected
1-23 months
Child Selected
2-11 years
Adolescent Selected
12-18 years
Adult Selected
19-65 years
Older Adult Selected
65+ years
Symptoms may start to appear at any time in life.
This information comes from Orphanet

Symptoms

The types of symptoms experienced, and their intensity, may vary among people with this disease. Your experience may be different from others, and you should consult your primary care provider (PCP) for more information.

This list does not include all possible symptoms related to this disease, but they may include:
Musculoskeletal System Musculoskeletal System

3 Symptoms

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Body Systems

Symptoms related to this disease may affect different systems of the body. Use the 'Filter and Sort' function to learn more about which body system(s) are affected by this disease and their associated symptom(s).

Medical Term

Hypotonia

Frequency
Uncommon
Very frequent
Very frequent
Always
Description

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

Synonym

Low muscle tone; Low or weak muscle tone; Muscle hypotonia; Muscular hypotonia

Low muscle tone; Low or weak muscle tone; Muscle hypotonia; Muscular hypotonia

3 Symptoms
This information comes from the Human Phenotype Ontology (HPO)

Causes

What Causes This Disease?

Genetic Changes

Carbamoyl-phosphate synthetase 1 deficiency is caused by harmful genetic changes, also known as pathogenic variants. Genetic changes can occur randomly, as a result of environmental factors, from parents passing them down to their children, or a combination of these. Additionally, they can occur before birth or at any time during a person's life. Learn more about genetic diseases from the National Library of Medicine (NLM).

If you suspect you may have this disease, you may want to start collecting your family health history. Information such as other family members who have had similar symptoms, when their/your symptoms first appeared, or exposures to any potential disease-causing environmental factors should be discussed with your medical team. This tool from the Surgeon General can help you collect your family health history.
Can This Disease Be Passed Down From Parent to Child?

Yes. It is possible for a biological parent to pass down pathogenic variants that cause or increase the chances of getting this disease to their child. This is known as inheritance. Knowing whether other family members have previously had this disease, also known as family health history, can be very important information for your medical team. This tool from the Surgeon General can help you collect your family health history.

There are multiple ways, or patterns, a disease can be inherited depending on the gene(s) involved. Based on GARD's current pathogenic variant data, this disease can be inherited in the following pattern(s):

Autosomal Recessive

"Autosomal" means the gene involved is located on one of the numbered chromosomes. "Recessive" means that a child must inherit two copies of the pathogenic variant, one from each biological parent, to be affected by the disease. A carrier is a person who only has one copy of the pathogenic variant. A carrier usually doesn't show any symptoms of the disease.

If both biological parents are carriers, there is a 25% their child inherits both copies of the pathogenic variant and is affected by the disease. Additionally, there is a 50% chance their child inherits only one copy of the pathogenic variant and is a carrier.

Learn more about inheritance patterns from the National Library of Medicine (NLM).

Advocacy and Support Groups

How Can Patient Organizations Help?

Patient organizations can help patients and families connect. They build public awareness of the disease and are a driving force behind research to improve patients' lives. They may offer online and in-person resources to help people live well with their disease. Many collaborate with medical experts and researchers.

Services of patient organizations differ, but may include:

  • Ways to connect to others and share personal stories
  • Easy-to-read information
  • Up-to-date treatment and research information
  • Patient registries
  • Lists of specialists or specialty centers
  • Financial aid and travel resources

Please note: GARD provides organizations for informational purposes only and not as an endorsement of their services. Please contact an organization directly if you have questions about the information or resources it provides.

Patient Organizations

6 Organizations

Organization Name

Who They Serve

Helpful Links

Country

Metabolic Support UK
People With

Carbamoyl-Phosphate Synthetase 1 Deficiency

Helpful Links
Country

United Kingdom

National Urea Cycle Disorders Foundation
People With

Carbamoyl-Phosphate Synthetase 1 Deficiency

Helpful Links
Country

United States

EveryLife Foundation for Rare Diseases
People With

Rare Diseases

Helpful Links
Country

United States

Genetic Alliance
People With

Rare Diseases

Helpful Links
Country

United States

Global Genes
People With

Rare Diseases

Helpful Links
Country

United States

National Organization for Rare Disorders
People With

Rare Diseases

Helpful Links
Country

United States

Participating in Clinical Studies

Clinical studies are part of clinical research and at the heart of all medical advances, including rare diseases. Participating in research helps researchers ultimately uncover better ways to treat, prevent, diagnose, and understand human diseases.

What Are Clinical Studies?

Clinical studies are medical research involving people as participants. There are two main types of clinical studies:

  1. Clinical trials determine if a new test or treatment for a disease is effective and safe by comparing groups receiving different tests/treatments.
  2. Observational studies involve recording changes over time among a specific group of people in their natural settings.
Learn more about clinical trials from this U.S. Food & Drug Administration webpage.

Why Participate in Clinical Studies?

People participate in clinical trials for many reasons. People with a disease may participate to receive the newest possible treatment and additional care from clinical study staff as well as to help others living with the same or similar disease. Healthy volunteers may participate to help others and to contribute to moving science forward.

To find the right clinical study we recommend you consult your doctors, other trusted medical professionals, and patient organizations. Additionally, you can use ClinicalTrials.gov to search for clinical studies by disease, terms, or location.

Join the All of Us Research Program!

The All of Us Research Program is inviting 1 million people from all backgrounds across the U.S. to help build one of the most diverse health databases in history. Researchers will use the data to learn how our biology, lifestyle, and environment affect health. This may one day help them find ways to treat and prevent diseases.

What if There Are No Available Clinical Studies?

ResearchMatch helps connect people interested in research studies  with researchers from top medical centers across the United States. Anyone from the U.S. can register with this free program funded by NIH. Researchers from participating institutions use the database to search for and invite patients or healthy volunteers who meet their study criteria to participate.

What Are Clinical Studies?

Clinical studies are medical research involving people as participants. There are two main types of clinical studies:
  1. Clinical trials determine if a new test or treatment for a disease is effective and safe by comparing groups receiving different tests/treatments.
  2. Observational studies involve recording changes over time among a specific group of people in their natural settings.
Learn more about clinical trials from this U.S. Food & Drug Administration webpage.
Read More

Why Participate in Clinical Studies?

People participate in clinical trials for many reasons. People with a disease may participate to receive the newest possible treatment and additional care from clinical study staff as well as to help others living with the same or similar disease. Healthy volunteers may participate to help others and to contribute to moving science forward.

To find the right clinical study we recommend you consult your doctors, other trusted medical professionals, and patient organizations. Additionally, you can use ClinicalTrials.gov to search for clinical studies by disease, terms, or location.
Read More

Join the All of Us Research Program!

The All of Us Research Program is inviting 1 million people from all backgrounds across the U.S. to help build one of the most diverse health databases in history. Researchers will use the data to learn how our biology, lifestyle, and environment affect health. This may one day help them find ways to treat and prevent diseases.

What if There Are No Available Clinical Studies?

ResearchMatch helps connect people interested in research studies  with researchers from top medical centers across the United States. Anyone from the U.S. can register with this free program funded by NIH. Researchers from participating institutions use the database to search for and invite patients or healthy volunteers who meet their study criteria to participate.

ClinicalTrials.gov, an affiliate of NIH, provides current information on clinical research studies in the United States and abroad. Talk to a trusted doctor before choosing to participate in any clinical study. We recommend checking this site often and searching for studies with related terms/synonyms to improve results.
Search ClinicalTrials.gov for this disease
Please contact GARD if you need help finding additional information or resources on rare diseases, including clinical studies. Note, GARD cannot enroll individuals in clinical studies.
1-888-205-2311
Available toll-free Monday through Friday from 12 pm to 6 pm Eastern Time
(Except: Federal Holidays)
Contact Form
Use the contact form to send your questions to a GARD Information Specialist.

Please allow 2 to 10 business days for us to respond.
ClinicalTrials.gov, an affiliate of NIH, provides current information on clinical research studies in the United States and abroad. Talk to a trusted doctor before choosing to participate in any clinical study. We recommend checking this site often and searching for studies with related terms/synonyms to improve results.
Search ClinicalTrials.gov for this disease
Please contact GARD if you need help finding additional information or resources on rare diseases, including clinical studies. Note, GARD cannot enroll individuals in clinical studies.
1-888-205-2311
Available toll-free Monday through Friday from 12 pm to 6 pm Eastern Time
(Except: Federal Holidays)
Contact Form
Use the contact form to send your questions to a GARD Information Specialist.

Please allow 2 to 10 business days for us to respond.
About the Disease

Learn about symptoms, cause, support, and research for a rare disease. 

Getting a Diagnosis

Take steps toward getting a diagnosis by working with your doctor, finding the right specialists, and coordinating medical care.

Living With the Disease

Find resources for patients and caregivers that address the challenges of living with a rare disease.

Getting a Diagnosis

Take steps toward getting a diagnosis by working with your doctor, finding the right specialists, and coordinating medical care.

Last Updated: November 2023