Overview
Isolated arhinencephaly is an extremely rare brain malformation in which the olfactory bulbs and tracts — the parts of the brain responsible for the sense of smell — fail to develop properly. The term 'arhinencephaly' literally means 'absence of the nose brain.' In this isolated form, the condition occurs on its own without being part of a larger brain malformation such as holoprosencephaly (where the front part of the brain does not divide correctly). People with isolated arhinencephaly typically have a complete or near-complete inability to smell, a condition known as anosmia. In some cases, there may be additional subtle neurological or developmental differences, but the hallmark feature is the absent or underdeveloped olfactory structures. Because the condition is so rare, it is not always detected at birth. It may be discovered incidentally during brain imaging performed for other reasons, or it may come to attention when a child or adult reports never having been able to smell. There is currently no cure or way to restore the missing brain structures. Treatment focuses on managing any associated difficulties and ensuring safety, since people who cannot smell may not detect dangers like smoke, gas leaks, or spoiled food. Genetic counseling may be offered to affected families to understand whether a hereditary cause is involved.
Key symptoms:
Complete inability to smell (anosmia)Reduced sense of smell (hyposmia)Reduced sense of tasteAbsent or underdeveloped olfactory bulbs on brain imagingPossible mild developmental delays in some casesDifficulty detecting dangerous odors like smoke or gas
Variable
Can be inherited in different ways depending on the underlying gene
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Isolated arhinencephaly.
View clinical trials →Clinical Trials
View all trials with filters →No actively recruiting trials found for Isolated arhinencephaly at this time.
New trials open frequently. Follow this disease to get notified.
Specialists
View all specialists →No specialists are currently listed for Isolated arhinencephaly.
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 arhinencephaly.
Community
No community posts yet. Be the first to share your experience with Isolated arhinencephaly.
Start the conversation →Latest news about Isolated arhinencephaly
No recent news articles for Isolated arhinencephaly.
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.Is my child's arhinencephaly truly isolated, or could it be part of a larger syndrome?,Should we pursue genetic testing to look for an underlying cause?,Are there any other brain structures that are affected?,What safety precautions should we take at home because of the inability to smell?,Is there any chance the sense of smell could develop over time?,What is the chance that future children could also have this condition?,Are there any clinical studies or research programs we could participate in?
Common questions about Isolated arhinencephaly
What is Isolated arhinencephaly?
Isolated arhinencephaly is an extremely rare brain malformation in which the olfactory bulbs and tracts — the parts of the brain responsible for the sense of smell — fail to develop properly. The term 'arhinencephaly' literally means 'absence of the nose brain.' In this isolated form, the condition occurs on its own without being part of a larger brain malformation such as holoprosencephaly (where the front part of the brain does not divide correctly). People with isolated arhinencephaly typically have a complete or near-complete inability to smell, a condition known as anosmia. In some cases,
At what age does Isolated arhinencephaly typically begin?
Typical onset of Isolated arhinencephaly is neonatal. Age of onset can vary across affected individuals.