sirenomelia

congenital disorder

Also known as: mermaid extremity, sirenomelus, symmelus

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Last updated

July 13, 2026

Quick Summary

Sirenomelia, also known as "mermaid extremity," is a rare congenital disorder characterized by the fusion of the legs to varying degrees. This severe abnormality also involves malformed bones within the legs, absence of anal and urinary orifices, and malformations of the genitals and parts of the intestinal and urinary tracts. It is a type of peromelia, which refers to the congenital absence or malformation of extremities, often caused by errors in limb bud development during early pregnancy. Treatment for significant limb malformations typically involves prosthetics and specialized training, with surgery sometimes used for minor deformities.1

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malformation
Somatic characters
…with no separate feet (sirenomelus or symmelus).
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…with no separate feet (sirenomelus or symmelus).
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peromelia
Sirenomelia (“mermaid extremity”) is a severe abnormality in which the legs are fused to a greater or lesser degree and contain malformed bones, the anal and urinary orifices are absent, and the genitals and parts of the intestinal and urinary tracts malformed.
Read More
Sirenomelia (“mermaid extremity”) is a severe abnormality in which the legs are fused to a greater or lesser degree and contain malformed bones, the anal and urinary orifices are absent, and the genitals and parts of the intestinal and urinary tracts malformed.
Read More