Overview
Congenital sucrase-isomaltase deficiency (CSID), also known as sucrose intolerance or genetic sucrase-isomaltase deficiency, is a rare inherited digestive disorder. It happens when the small intestine does not make enough of two enzymes — sucrase and isomaltase — that are needed to break down certain sugars and starches. Without these enzymes, sugars like sucrose (table sugar) and some starches cannot be properly digested and absorbed. When undigested sugars reach the large intestine, bacteria ferment them, causing uncomfortable and sometimes severe digestive symptoms. These symptoms typically appear when a baby starts eating foods containing sugar or starch, often around the time of weaning. Common symptoms include chronic watery diarrhea, bloating, gas, stomach cramps, and nausea. In young children, repeated diarrhea can lead to poor weight gain and growth problems if the condition is not recognized and managed. The good news is that CSID can be managed effectively. Treatment focuses on limiting sucrose and starch in the diet and, importantly, an FDA-approved enzyme replacement therapy called sacrosidase (Sucraid) is available. With proper diagnosis and management, most people with CSID can lead healthy, active lives. Early diagnosis is key to preventing nutritional problems and improving quality of life.
Key symptoms:
Chronic watery diarrhea after eating sugary or starchy foodsBloating and a swollen, uncomfortable bellyExcessive gas and flatulenceStomach cramps and painNausea and vomitingPoor weight gain or failure to thrive in infants and young childrenIrritability in babies after feedingDehydration from frequent diarrheaFrothy or acidic-smelling stoolsFatigue related to poor nutrition and fluid loss
Clinical phenotype terms (14)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Infantile
Begins in infancy, roughly 1 month to 2 years old
FDA & Trial Timeline
4 eventsUniversity of Nottingham
Lovisenberg Diakonale Hospital — NA
Sucraid: FDA approved
Oral replacement therapy of the genetically determined sucrase deficiency, which is part of congenital sucrease-isomaltase deficiency.
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
3 availableNormocarb HF
Use as a replacement solution in Continuous Renal Replacement Therapy (CRRT) to replace water and to correct electrolytes and acid-base imbalances
Cimetidine
Maintenance therapy for duodenal ulcer patients at reduced dosage after healing of active ulcer
Sucraid
Oral replacement therapy of the genetically determined sucrase deficiency, which is part of congenital sucrease-isomaltase deficiency.
Clinical Trials
View all trials with filters →No actively recruiting trials found for Congenital sucrase-isomaltase deficiency at this time.
New trials open frequently. Follow this disease to get notified.
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
Financial Resources
1 resourcesTravel Grants
No travel grants are currently matched to Congenital sucrase-isomaltase deficiency.
Community
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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.How do I know if my child's SI gene mutations are the cause of their symptoms, and should other family members be tested?,Is sacrosidase (Sucraid) the right treatment for my child, and how do I use it correctly?,What foods does my child need to avoid, and are there hidden sources of sucrose I should know about?,How will we monitor my child's growth and nutrition over time?,Will my child's ability to tolerate sucrose change as they get older?,Are there any clinical trials or new treatments for CSID that we should consider?,What should I do if my child has a severe diarrhea episode and becomes dehydrated?
Common questions about Congenital sucrase-isomaltase deficiency
What is Congenital sucrase-isomaltase deficiency?
Congenital sucrase-isomaltase deficiency (CSID), also known as sucrose intolerance or genetic sucrase-isomaltase deficiency, is a rare inherited digestive disorder. It happens when the small intestine does not make enough of two enzymes — sucrase and isomaltase — that are needed to break down certain sugars and starches. Without these enzymes, sugars like sucrose (table sugar) and some starches cannot be properly digested and absorbed. When undigested sugars reach the large intestine, bacteria ferment them, causing uncomfortable and sometimes severe digestive symptoms. These symptoms typicall
How is Congenital sucrase-isomaltase deficiency inherited?
Congenital sucrase-isomaltase deficiency follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Congenital sucrase-isomaltase deficiency typically begin?
Typical onset of Congenital sucrase-isomaltase deficiency is infantile. Age of onset can vary across affected individuals.
Which specialists treat Congenital sucrase-isomaltase deficiency?
9 specialists and care centers treating Congenital sucrase-isomaltase deficiency are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.
What treatment and support options exist for Congenital sucrase-isomaltase deficiency?
1 patient support program are currently tracked on UniteRare for Congenital sucrase-isomaltase deficiency. See the treatments and support programs sections for copay assistance, eligibility, and contact details.