Rare diseases · Sign or symptom

Absence of the sacrum

HP:0010305

What it means

Absence (aplasia) of the sacrum.

Rare diseases that can present with this3

Very common80–99%

1

Common30–79%

1

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: Absent sacrum · Sacral agenesis · Sacrococcygeal agenesis

Absence of the sacrum

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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.