Overview
Hypocalcemic vitamin D-dependent rickets, also known as vitamin D-dependent rickets (VDDR), is a group of rare inherited disorders that affect how the body processes vitamin D. Vitamin D is essential for absorbing calcium from food and keeping bones strong. In this condition, the body either cannot properly convert vitamin D into its active form or cannot respond to active vitamin D normally. This leads to low calcium levels in the blood (hypocalcemia), which causes the bones to become soft and weak — a condition called rickets in children. The main symptoms usually appear in infancy or early childhood and include bowed legs, delayed growth, muscle weakness, bone pain, and dental problems. Children may have trouble walking or experience frequent fractures. Seizures can occur due to very low calcium levels. Without treatment, the disease can lead to significant skeletal deformities. Treatment depends on the specific type of vitamin D-dependent rickets. Type 1 (also called 1-alpha-hydroxylase deficiency or VDDR type 1A) is treated with active vitamin D (calcitriol), which bypasses the enzyme deficiency. Type 2 (also called hereditary vitamin D-resistant rickets or VDDR type 2A) involves resistance to vitamin D at the receptor level and may require very high doses of calcium, sometimes given intravenously. With early diagnosis and proper treatment, many patients can achieve significant improvement in bone health and growth, though lifelong therapy is usually needed.
Also known as:
Key symptoms:
Bowed legs or knock kneesDelayed growth and short statureMuscle weaknessBone pain and tendernessFrequent bone fracturesDelayed walking or waddling gaitSeizures from low calciumDental problems such as delayed tooth eruption or enamel defectsWidening of the wrists and anklesSoft skull bones in infantsIrritability and fussiness in babiesNumbness or tingling in hands and feetMuscle cramps or spasmsHair loss (in type 2 cases)
Clinical phenotype terms (46)— 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
Treatments
No FDA-approved treatments are currently listed for Hypocalcemic vitamin D-dependent rickets.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Hypocalcemic vitamin D-dependent rickets at this time.
New trials open frequently. Follow this disease to get notified.
Specialists
View all specialists →No specialists are currently listed for Hypocalcemic vitamin D-dependent rickets.
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 Hypocalcemic vitamin D-dependent rickets.
Community
No community posts yet. Be the first to share your experience with Hypocalcemic vitamin D-dependent rickets.
Start the conversation →Latest news about Hypocalcemic vitamin D-dependent rickets
No recent news articles for Hypocalcemic vitamin D-dependent rickets.
Follow this condition to be notified when news becomes available.
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.What specific type of vitamin D-dependent rickets does my child have, and which gene is affected?,What are the target blood calcium and vitamin D levels we should aim for with treatment?,How often will blood tests and monitoring be needed?,What are the signs that the medication dose needs to be adjusted?,Are there any activities or sports my child should avoid?,What should I do if my child has a seizure or shows signs of very low calcium?,Should other family members be tested for this condition?
Common questions about Hypocalcemic vitamin D-dependent rickets
What is Hypocalcemic vitamin D-dependent rickets?
Hypocalcemic vitamin D-dependent rickets, also known as vitamin D-dependent rickets (VDDR), is a group of rare inherited disorders that affect how the body processes vitamin D. Vitamin D is essential for absorbing calcium from food and keeping bones strong. In this condition, the body either cannot properly convert vitamin D into its active form or cannot respond to active vitamin D normally. This leads to low calcium levels in the blood (hypocalcemia), which causes the bones to become soft and weak — a condition called rickets in children. The main symptoms usually appear in infancy or early
How is Hypocalcemic vitamin D-dependent rickets inherited?
Hypocalcemic vitamin D-dependent rickets follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Hypocalcemic vitamin D-dependent rickets typically begin?
Typical onset of Hypocalcemic vitamin D-dependent rickets is infantile. Age of onset can vary across affected individuals.