Rare diseases · Sign or symptom
Cervical C2/C3 vertebral fusion
HP:0004602
What it means
Fusion of cervical vertebrae at C2 and C3, caused by a failure in the normal segmentation or division of the cervical vertebrae during the early weeks of fetal development, leading to a short neck with a low hairline at the back of the head, and restricted mobility of the upper spine.
Rare diseases that can present with this5
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Fusion of cervical vertebrae c2-3 · Klippel-Feil anomaly · Klippel-Feil syndrome
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.