Overview
Isolated exencephaly is a very rare and severe birth defect of the brain and skull. In this condition, the brain develops outside of the skull instead of being protected inside it. The skull bones do not close properly during early pregnancy, leaving the brain exposed. This is different from anencephaly, where much of the brain is absent — in exencephaly, the brain tissue is present but sits outside the skull, often covered only by a thin membrane or exposed directly. The term 'isolated' means this condition occurs on its own, without other major birth defects being the main feature. Exencephaly is considered a neural tube defect, meaning it happens when the neural tube — the structure that becomes the brain and spinal cord — does not close correctly in the first few weeks of pregnancy. This usually occurs between 3 and 4 weeks after conception, often before a person even knows they are pregnant. Because the brain is unprotected and exposed, this condition is not compatible with life outside the womb in most cases. Babies diagnosed with exencephaly typically do not survive to birth or pass away very shortly after. There is no cure or treatment that can repair the brain or skull in this condition. Care is focused on supporting families through the diagnosis and, in some cases, comfort care for the newborn.
Key symptoms:
Brain tissue visible outside the skull at birthAbsent or incomplete skull bones over the top of the headAbnormal head shapeExposed brain tissue, sometimes covered by a thin membraneNo normal scalp covering the top of the headStillbirth or death shortly after birth in most casesAbnormal fetal movements detected during pregnancy in some cases
Clinical phenotype terms (16)— hover any for plain English
Multifactorial
Caused by a mix of several genes and environmental factors
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Isolated exencephaly.
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Specialists
View all specialists →No specialists are currently listed for Isolated exencephaly.
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 Isolated exencephaly.
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.What caused this to happen, and is there a genetic reason we should know about?,What is the chance this could happen again in a future pregnancy?,What dose of folic acid should I take before and during my next pregnancy?,What are our options now that we have this diagnosis?,What does comfort care look like if our baby is born alive?,Are there support groups or counselors who specialize in helping families through this kind of loss?,Should we have genetic testing done, and if so, what type?
Common questions about Isolated exencephaly
What is Isolated exencephaly?
Isolated exencephaly is a very rare and severe birth defect of the brain and skull. In this condition, the brain develops outside of the skull instead of being protected inside it. The skull bones do not close properly during early pregnancy, leaving the brain exposed. This is different from anencephaly, where much of the brain is absent — in exencephaly, the brain tissue is present but sits outside the skull, often covered only by a thin membrane or exposed directly. The term 'isolated' means this condition occurs on its own, without other major birth defects being the main feature. Exenceph
How is Isolated exencephaly inherited?
Isolated exencephaly follows a multifactorial inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Isolated exencephaly typically begin?
Typical onset of Isolated exencephaly is neonatal. Age of onset can vary across affected individuals.