Overview
Autosomal recessive hypophosphatemic rickets (ARHR) is a rare inherited bone disorder caused by the body's inability to properly manage phosphate, an essential mineral needed for strong and healthy bones and teeth. In this condition, the kidneys lose too much phosphate into the urine, leading to low phosphate levels in the blood (hypophosphatemia). Without enough phosphate, bones cannot mineralize properly, which means they become soft and weak. Children with ARHR typically develop signs of rickets, including bowed legs or knock knees, short stature, bone pain, and dental problems such as tooth abscesses. The condition usually becomes apparent in early childhood when a child begins to walk and bear weight on their legs. Some patients may also experience muscle weakness and difficulty walking. Treatment focuses on replacing phosphate and active vitamin D (calcitriol) to improve bone mineralization and support normal growth. With early diagnosis and consistent treatment, many of the skeletal problems can be improved or prevented. Regular monitoring by specialists is important to adjust treatment doses and watch for complications such as kidney calcification (nephrocalcinosis). In some cases, surgical correction of bone deformities may be needed. ARHR is sometimes also referred to as autosomal recessive vitamin D-resistant rickets type 1 or type 2, depending on the gene involved.
Also known as:
Key symptoms:
Bowed legs or knock kneesShort stature or poor growthBone painMuscle weaknessDifficulty walking or waddling gaitDelayed walking milestonesFrequent dental abscesses or tooth decaySoft or fragile bones that fracture easilyWidening of the wrists or anklesBone deformities of the legsFatigue or low energyDelayed closure of the skull's soft spots (fontanelles)Poor dental enamel
Clinical phenotype terms (37)— hover any for plain English
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Childhood
Begins in childhood, roughly ages 1 to 12
FDA & Trial Timeline
4 eventsInozyme Pharma — PHASE3
Inozyme Pharma
Inozyme Pharma — PHASE3
Inozyme Pharma — PHASE1
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Autosomal recessive hypophosphatemic rickets.
3 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Rare Disease Specialist
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 Autosomal recessive hypophosphatemic rickets.
Community
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Start the conversation →Latest news about Autosomal recessive hypophosphatemic rickets
Disease timeline:
New recruiting trial: PROPEL - A Prospective Observational Patient Registry to Evaluate ENPP1 and ABCC6 Deficiency
A new clinical trial is recruiting patients for Autosomal recessive hypophosphatemic rickets
New recruiting trial: ENERGY 2: Evaluation of the Efficacy and Safety of INZ-701 in Infants With ENPP1 Deficiency
A new clinical trial is recruiting patients for Autosomal recessive hypophosphatemic rickets
Caregiver Resources
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Family & Caregiver Grants
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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 gene is causing my child's condition, and does that affect the treatment plan?,How often will my child need blood tests, urine tests, and kidney ultrasounds to monitor treatment?,What are the signs that the phosphate or vitamin D dose needs to be adjusted?,Is burosumab (Crysvita) an option for my child's specific type of ARHR?,At what point should we consider orthopedic surgery for leg bowing?,What dental precautions should we take to prevent abscesses and tooth problems?,Should other family members be tested to see if they are carriers?
Common questions about Autosomal recessive hypophosphatemic rickets
What is Autosomal recessive hypophosphatemic rickets?
Autosomal recessive hypophosphatemic rickets (ARHR) is a rare inherited bone disorder caused by the body's inability to properly manage phosphate, an essential mineral needed for strong and healthy bones and teeth. In this condition, the kidneys lose too much phosphate into the urine, leading to low phosphate levels in the blood (hypophosphatemia). Without enough phosphate, bones cannot mineralize properly, which means they become soft and weak. Children with ARHR typically develop signs of rickets, including bowed legs or knock knees, short stature, bone pain, and dental problems such as too
How is Autosomal recessive hypophosphatemic rickets inherited?
Autosomal recessive hypophosphatemic rickets follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Autosomal recessive hypophosphatemic rickets typically begin?
Typical onset of Autosomal recessive hypophosphatemic rickets is childhood. Age of onset can vary across affected individuals.
Are there clinical trials for Autosomal recessive hypophosphatemic rickets?
Yes — 3 recruiting clinical trials are currently listed for Autosomal recessive hypophosphatemic rickets on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat Autosomal recessive hypophosphatemic rickets?
4 specialists and care centers treating Autosomal recessive hypophosphatemic rickets are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.