Overview
Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome (sometimes called FHONDA syndrome) is a very rare genetic eye condition that affects several parts of the eye at the same time. The syndrome has three main features. First, foveal hypoplasia means the fovea — the small central area of the retina responsible for sharp, detailed vision — does not develop properly. This leads to reduced central vision and often causes involuntary eye movements called nystagmus. Second, there is an optic nerve decussation defect, which means the nerve fibers that carry visual information from the eyes to the brain do not cross over correctly at the optic chiasm. This abnormal crossing pattern is similar to what is seen in albinism, but patients with FHONDA syndrome do not have the skin, hair, or eye color changes associated with albinism. Third, anterior segment dysgenesis refers to abnormal development of the front part of the eye, including the iris, cornea, and lens area, which can sometimes raise the risk of glaucoma. Because this condition affects how the eyes develop before birth, symptoms are typically present from infancy. There is currently no cure for FHONDA syndrome. Treatment focuses on managing symptoms such as correcting refractive errors with glasses, monitoring for glaucoma, and providing low-vision support and rehabilitation to help patients make the most of their remaining vision.
Also known as:
Key symptoms:
Reduced central vision from birthInvoluntary back-and-forth eye movements (nystagmus)Underdeveloped central part of the retina (fovea)Abnormal development of the front part of the eyeIris abnormalities such as thinning or unusual shapePossible increased eye pressure or glaucomaDifficulty with fine detail tasks like readingLight sensitivity in some casesMisrouting of visual nerve signals from the eyes to the brainPossible strabismus (crossed or misaligned eyes)
Autosomal dominant
Passed on from just one parent; each child has about a 50% chance of inheriting it
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome.
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Specialists
View all specialists →No specialists are currently listed for Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome.
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 Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome.
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.How severe is the foveal hypoplasia, and what level of vision can we expect?,Is there any sign of glaucoma, and how often should eye pressure be checked?,What low-vision aids or assistive devices would be most helpful?,Should other family members be tested for the SLC38A8 gene change?,What school accommodations should we request for our child?,Are there any clinical trials or new research studies we should know about?,How will this condition change over time, and what should we watch for?
Common questions about Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome
What is Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome?
Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome (sometimes called FHONDA syndrome) is a very rare genetic eye condition that affects several parts of the eye at the same time. The syndrome has three main features. First, foveal hypoplasia means the fovea — the small central area of the retina responsible for sharp, detailed vision — does not develop properly. This leads to reduced central vision and often causes involuntary eye movements called nystagmus. Second, there is an optic nerve decussation defect, which means the nerve fibers that carry visual inf
How is Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome inherited?
Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome follows a autosomal dominant inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome typically begin?
Typical onset of Foveal hypoplasia-optic nerve decussation defect-anterior segment dysgenesis syndrome is neonatal. Age of onset can vary across affected individuals.