Rare diseases · Sign or symptom

Vertebral segmentation defect

HP:0003422

What it means

An abnormality related to a defect of vertebral separation during development.

The vertebral column derives from somites, transient paired segments of mesoderm that surround the neural tube in the early embryo. The formation of the vertebrar involves many processes including resegmentation of the rostral and caudal regions of adjacent somites that then fuse to form vertebral elements. Disruption of these processes can a cause of severe segmentation defects of the vetebrae. The frequency of segmentation defects of the vetebra has been estimated at 0.5 of 1000 births. The range of segmentation defects includes left-right uneven formation of somites that results in hemivertebrae or wedge vertebrae. Incomplete segmentation can result in fused segments such as block vertebrae. A failure of the process of resegmentation and migration of the sclerotomal compartment can result in a failure of midline fusion, such as butterfly vertebrae.

Rare diseases that can present with this49

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: Abnormal spinal segmentation

Vertebral segmentation defect

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This 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.