Overview
Isolated anencephaly (also called exencephaly) is a severe birth defect in which a baby is born without major parts of the brain and skull. During early pregnancy, the neural tube — the structure that eventually forms the brain and spinal cord — fails to close properly at the head end. This results in the absence of a large portion of the brain, skull, and scalp. Exencephaly is considered an earlier stage where brain tissue is exposed but not yet destroyed, while anencephaly represents the final result after the exposed brain tissue degrades. Babies with anencephaly are typically missing the cerebral hemispheres, which are responsible for thinking, movement, and sensation. The remaining brain tissue is often covered only by a thin membrane. Affected babies may still have a brainstem, which can support basic functions like breathing and reflexes for a short time after birth. This condition is usually detected during pregnancy through routine ultrasound or blood screening tests. Sadly, anencephaly is not compatible with long-term survival. Most pregnancies affected by anencephaly end in stillbirth, and babies born alive typically survive only hours to days. There is no cure or surgical treatment that can correct the missing brain tissue. Prevention efforts focus on adequate folic acid intake before and during early pregnancy, which has been shown to significantly reduce the risk of neural tube defects including anencephaly. Supportive and compassionate care is provided to families facing this diagnosis.
Key symptoms:
Absence of major parts of the brainMissing skull bones (calvarium)Missing scalp over the top of the headExposed or absent brain tissueBulging eyes due to shallow eye socketsAbsence of consciousness or awarenessNo ability to think, see, or hear meaningfullyReflexive movements onlyInability to feed normallyInability to regulate body temperature
Clinical phenotype terms (2)
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 anencephaly/exencephaly.
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Specialists
View all specialists →No specialists are currently listed for Isolated anencephaly/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 anencephaly/exencephaly.
Community
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Caregiver Resources
NORD Caregiver Resources
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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.How certain is the diagnosis, and are additional tests needed to confirm it?,Are there any chromosomal or genetic abnormalities that should be tested for?,What are my options for the remainder of this pregnancy?,What will happen at delivery, and what kind of care will my baby receive?,What is the chance this could happen again in a future pregnancy?,How much folic acid should I take before and during my next pregnancy?,Can you refer me to a genetic counselor and grief support services?
Common questions about Isolated anencephaly/exencephaly
What is Isolated anencephaly/exencephaly?
Isolated anencephaly (also called exencephaly) is a severe birth defect in which a baby is born without major parts of the brain and skull. During early pregnancy, the neural tube — the structure that eventually forms the brain and spinal cord — fails to close properly at the head end. This results in the absence of a large portion of the brain, skull, and scalp. Exencephaly is considered an earlier stage where brain tissue is exposed but not yet destroyed, while anencephaly represents the final result after the exposed brain tissue degrades. Babies with anencephaly are typically missing the
How is Isolated anencephaly/exencephaly inherited?
Isolated anencephaly/exencephaly follows a multifactorial inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Isolated anencephaly/exencephaly typically begin?
Typical onset of Isolated anencephaly/exencephaly is neonatal. Age of onset can vary across affected individuals.