Rare diseases · Sign or symptom
Abnormality of the proximal phalanx of the thumb
Abnormal innermost thumb bone
HP:0009618
What it means
An anomaly of the shape or form of the proximal phalanx of the thumb.
In contrast to the proximal phalanges of the digits 2-5, the proximal phalanx of the thumb is embryologically equivalent to the middle phalanges of the other digits, whereas the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the other digits. {xref="https://orcid.org/0000-0002-0736-9199"}
Part of the broader category
Also called: Abnormality of proximal thumb phalanx
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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.