Overview
Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis (ABS with steroidogenesis defect) is a rare genetic condition caused by changes in the POR gene, which provides instructions for making an enzyme called P450 oxidoreductase. This enzyme is essential for the body to produce steroid hormones — including cortisol, sex hormones, and other important chemicals — and for processing certain medications. When POR does not work properly, the body cannot make these hormones correctly, leading to a wide range of problems. The condition affects the skeleton, the hormone system, and the development of reproductive organs. Babies are often born with fused skull bones (craniosynostosis), which can affect the shape of the head and face. The bones of the arms and legs may also be unusually shaped or bent. Because steroid hormone production is disrupted, both boys and girls may have ambiguous or atypical genitalia at birth, meaning it can be hard to tell the sex of the baby from appearance alone. Girls may show signs of masculinization, while boys may appear undermasculinized. Treatment focuses on managing the individual symptoms. Surgery may be needed to correct skull or limb problems. Hormone replacement therapy can help address the steroid deficiency, particularly cortisol, which is critical for handling stress and illness. With careful medical management, many children can do well, though lifelong monitoring is usually needed.
Key symptoms:
Fused skull bones (craniosynostosis) causing an unusual head shapeMidface underdevelopment giving a flattened facial appearanceBowed or bent arm and leg bonesStiff or fused joints (joint contractures) limiting movementAmbiguous or atypical genitalia at birthLow cortisol levels (adrenal insufficiency) causing fatigue and poor stress responseAbnormal sex hormone levels affecting puberty and fertilityChoanal stenosis or atresia (narrowed or blocked nasal passages)Ear abnormalitiesShort statureKidney or urinary tract abnormalities in some casesDelayed puberty or absent puberty without treatment
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)
Treatments
No FDA-approved treatments are currently listed for Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis.
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Specialists
View all specialists →No specialists are currently listed for Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis.
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 Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
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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.Does my child need cortisol replacement therapy, and how do I manage sick-day dosing at home?,What surgeries might be needed for the skull or limbs, and when should they happen?,How will my child's hormone levels be monitored as they grow, and what should I watch for at puberty?,What is the plan for managing my child's genital development, and who should be involved in those decisions?,Are there any restrictions on activities or medications because of the adrenal insufficiency?,Should other family members be tested for the POR gene change?,What support services — such as physiotherapy, psychology, or educational support — should we be accessing?
Common questions about Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis
What is Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis?
Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis (ABS with steroidogenesis defect) is a rare genetic condition caused by changes in the POR gene, which provides instructions for making an enzyme called P450 oxidoreductase. This enzyme is essential for the body to produce steroid hormones — including cortisol, sex hormones, and other important chemicals — and for processing certain medications. When POR does not work properly, the body cannot make these hormones correctly, leading to a wide range of problems. The condition affects the skeleton, the hormone system, an
How is Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis inherited?
Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis typically begin?
Typical onset of Antley-Bixler syndrome with genital anomaly and disorder of steroidogenesis is neonatal. Age of onset can vary across affected individuals.