Overview
Congenital lactase deficiency (CLD), also known as congenital alactasia or Finnic type congenital lactase deficiency, is a very rare inherited condition present from birth. It affects the small intestine's ability to produce lactase, the enzyme needed to break down lactose — the natural sugar found in breast milk and formula. Without enough lactase, lactose cannot be digested properly, and it passes undigested into the large intestine where bacteria ferment it, causing serious digestive problems. Babies with congenital lactase deficiency begin showing symptoms as soon as they start feeding on breast milk or regular infant formula. The condition is different from the much more common 'adult-type' lactose intolerance, which develops gradually later in life. In congenital lactase deficiency, the enzyme is essentially absent from birth due to a change (mutation) in the LCT gene. The main treatment is removing lactose completely from the diet, starting immediately after birth. Babies are switched to lactose-free formula, which allows normal growth and development. With early diagnosis and strict dietary management, children with this condition can live healthy, normal lives. However, they must avoid lactose-containing foods throughout their entire life to prevent symptoms.
Key symptoms:
Severe watery diarrhea starting within days of birthBloating and a swollen, uncomfortable bellyExcessive gasVomiting after feedingPoor weight gain or weight loss in newbornsDehydration due to fluid loss from diarrheaIrritability and excessive cryingFrothy or acidic-smelling stoolsDiaper rash from acidic stoolsFailure to thrive if not diagnosed and treated quickly
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
FDA & Trial Timeline
1 eventAlexandria University — NA
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Congenital lactase deficiency.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Congenital lactase 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
Travel Grants
No travel grants are currently matched to Congenital lactase deficiency.
Community
No community posts yet. Be the first to share your experience with Congenital lactase deficiency.
Start the conversation →Latest news about Congenital lactase deficiency
Disease timeline:
New recruiting trial: Effect OF Lactase Enzyme Supplements ON Intolerance IN Preterm Neonates
A new clinical trial is recruiting patients for Congenital lactase deficiency
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 make sure my baby or child gets enough calcium and vitamin D without dairy products?,What hidden sources of lactose should I watch out for in foods, medications, or supplements?,How often should my child be seen by a dietitian or gastroenterologist?,Are there any long-term health risks I should monitor for, such as bone density?,Should other family members be tested for this condition or for carrier status?,What should I do if my child accidentally eats something with lactose?,Are there any clinical trials or new treatments being studied for this condition?
Common questions about Congenital lactase deficiency
What is Congenital lactase deficiency?
Congenital lactase deficiency (CLD), also known as congenital alactasia or Finnic type congenital lactase deficiency, is a very rare inherited condition present from birth. It affects the small intestine's ability to produce lactase, the enzyme needed to break down lactose — the natural sugar found in breast milk and formula. Without enough lactase, lactose cannot be digested properly, and it passes undigested into the large intestine where bacteria ferment it, causing serious digestive problems. Babies with congenital lactase deficiency begin showing symptoms as soon as they start feeding on
How is Congenital lactase deficiency inherited?
Congenital lactase deficiency follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Congenital lactase deficiency typically begin?
Typical onset of Congenital lactase deficiency is neonatal. Age of onset can vary across affected individuals.
Which specialists treat Congenital lactase deficiency?
4 specialists and care centers treating Congenital lactase deficiency are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.