Overview
Disorders of pyrimidine metabolism are a group of rare inherited conditions where the body cannot properly break down or build pyrimidines — a type of chemical building block used to make DNA and RNA. Pyrimidines include substances called uracil, thymine, and cytosine. When the enzymes responsible for processing these substances do not work correctly, harmful byproducts can build up in the body, or important molecules may be in short supply. This can affect many organs and systems, especially the brain and nervous system. There are several different disorders within this group, each caused by a fault in a different enzyme. Examples include dihydropyrimidine dehydrogenase (DPD) deficiency, dihydropyrimidinase deficiency, beta-ureidopropionase deficiency, and UMP synthase deficiency (also called orotic aciduria). Symptoms vary widely depending on which enzyme is affected, but can include intellectual disability, seizures, developmental delays, and problems with movement. Some people have very mild symptoms or none at all, while others are more severely affected. Treatment depends on the specific disorder. Some forms can be managed with dietary changes or supplements. There is currently no cure for most of these conditions, but supportive care can help manage symptoms and improve quality of life. Early diagnosis is important because some treatments work best when started early.
Key symptoms:
Intellectual disability or learning difficultiesSeizures or epilepsyDelayed development in speech and motor skillsMuscle weakness or poor muscle toneAbnormal movements or coordination problemsBehavioral problems or autism-like featuresFailure to thrive or poor growth in infancyAnemia (low red blood cell count)Increased levels of certain chemicals in urine (detected on lab tests)Sensitivity to certain chemotherapy drugs (especially 5-fluorouracil) in DPD deficiency
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Variable
Can begin at different ages, from infancy through adulthood
FDA & Trial Timeline
1 eventUCB BIOSCIENCES, Inc. — PHASE2
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Disorder of pyrimidine metabolism.
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Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Disorder of pyrimidine metabolism.
Community
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Start the conversation →Latest news about Disorder of pyrimidine metabolism
Disease timeline:
New recruiting trial: Deoxynucleosides Pyrimidines as Treatment for Mitochondrial Depletion Syndrome
A new clinical trial is recruiting patients for Disorder of pyrimidine metabolism
Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.Which specific disorder of pyrimidine metabolism does my child or I have, and which gene or enzyme is affected?,Are there any medications or treatments I must avoid because of this condition?,What therapies or supplements might help manage symptoms?,Should other family members be tested for this condition?,What signs should prompt me to seek emergency care?,Are there any clinical trials or research studies we could participate in?,What specialists should be part of our long-term care team?
Common questions about Disorder of pyrimidine metabolism
What is Disorder of pyrimidine metabolism?
Disorders of pyrimidine metabolism are a group of rare inherited conditions where the body cannot properly break down or build pyrimidines — a type of chemical building block used to make DNA and RNA. Pyrimidines include substances called uracil, thymine, and cytosine. When the enzymes responsible for processing these substances do not work correctly, harmful byproducts can build up in the body, or important molecules may be in short supply. This can affect many organs and systems, especially the brain and nervous system. There are several different disorders within this group, each caused by
How is Disorder of pyrimidine metabolism inherited?
Disorder of pyrimidine metabolism follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
Which specialists treat Disorder of pyrimidine metabolism?
25 specialists and care centers treating Disorder of pyrimidine metabolism are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.