Overview
Dihydropyrimidinuria, also known as dihydropyrimidine dehydrogenase deficiency or DPD deficiency, is a rare inherited metabolic disorder. It happens when the body cannot properly break down certain building blocks of DNA called pyrimidines — specifically uracil and thymine. This is because an enzyme called dihydropyrimidine dehydrogenase (DPD) does not work correctly. As a result, uracil and thymine build up in the blood and urine, which gives the condition its name. The symptoms of dihydropyrimidinuria can vary widely from person to person. Some people have no symptoms at all and are only discovered by chance during routine testing. Others, especially children, may experience intellectual disability, delayed development, seizures, and movement problems. Muscle tone issues and behavioral difficulties have also been reported. One of the most important clinical concerns is that people with DPD deficiency can have a life-threatening reaction to a common chemotherapy drug called 5-fluorouracil (5-FU) and related drugs like capecitabine. These medications are normally broken down by the DPD enzyme, so people who lack it can experience severe or fatal toxicity even from standard doses. There is currently no cure, but management focuses on avoiding harmful medications and treating symptoms as they arise.
Also known as:
Key symptoms:
Intellectual disability or learning difficultiesDelayed speech and language developmentDelayed motor development (late walking or sitting)Seizures or epilepsyLow or high muscle toneBehavioral problems or autism-like featuresSmall head size (microcephaly) in some casesElevated levels of uracil and thymine in urineSevere reaction to 5-fluorouracil chemotherapySome people have no symptoms at all
Clinical phenotype terms (20)— hover any for plain English
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
Treatments
No FDA-approved treatments are currently listed for Dihydropyrimidinuria.
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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 Dihydropyrimidinuria.
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Caregiver Resources
NORD Caregiver Resources
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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.What level of DPD enzyme activity do I have, and what does that mean for my health?,Should all of my family members be tested for this condition?,What should I do if I ever need chemotherapy — are there safe alternatives to 5-fluorouracil?,Should I carry a medical alert card or wear a medical ID bracelet?,Are there any other medications I should avoid because of this condition?,What therapies or support services are available if my child has developmental delays?,How often should I have follow-up appointments, and what monitoring is needed?
Common questions about Dihydropyrimidinuria
What is Dihydropyrimidinuria?
Dihydropyrimidinuria, also known as dihydropyrimidine dehydrogenase deficiency or DPD deficiency, is a rare inherited metabolic disorder. It happens when the body cannot properly break down certain building blocks of DNA called pyrimidines — specifically uracil and thymine. This is because an enzyme called dihydropyrimidine dehydrogenase (DPD) does not work correctly. As a result, uracil and thymine build up in the blood and urine, which gives the condition its name. The symptoms of dihydropyrimidinuria can vary widely from person to person. Some people have no symptoms at all and are only di
How is Dihydropyrimidinuria inherited?
Dihydropyrimidinuria follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
Which specialists treat Dihydropyrimidinuria?
1 specialists and care centers treating Dihydropyrimidinuria are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.