Rare diseases · Sign or symptom
Radioulnar synostosis
Fused forearm bones
HP:0002974
What it means
An abnormal osseous union (fusion) between the radius and the ulna.
Rare diseases that can present with this41
Very common80–99%
12- 3MC syndrome
- 48,XYYY syndrome
- 49,XYYYY syndrome
- Craniosynostosis-hydrocephalus-Arnold-Chiari malformation type I-radioulnar synostosis syndrome
- Isolated humero-radio-ulnar synostosis
- Isolated radio-ulnar synostosis
- Marden-Walker syndrome
- Mesomelic dysplasia, Nievergelt type
- Ophthalmomandibulomelic dysplasia
- Radio-ulnar synostosis-amegakaryocytic thrombocytopenia syndrome
- Radioulnar synostosis-developmental delay-hypotonia syndrome
- Radioulnar synostosis-microcephaly-scoliosis syndrome
Common30–79%
16- 48,XXXY syndrome
- 48,XXYY syndrome
- 49,XXXXY syndrome
- Abruzzo-Erickson syndrome
- Acrofacial dysostosis, Rodríguez type
- Cenani-Lenz syndrome
- Contractures-developmental delay-Pierre Robin syndrome
- Cornelia de Lange syndrome
- Desbuquois syndrome
- IVIC syndrome
- Juberg-Hayward syndrome
- Oculofaciocardiodental syndrome
- Pentasomy X syndrome
- PHAVER syndrome
- Roberts syndrome
- Tetrasomy X syndrome
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
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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.