What is the definition of Sirenomelia?
Sirenomelia is a birth defect in which affected infants are born with a single lower extremity or with two legs that are fused together. The symptoms and physical findings associated with the condition vary greatly among affected individuals and may include malformations of the spine and skeletal system (commonly with vertebrae either absent or defective); absent or underdeveloped internal and external sex organs, rectum, kidneys and/or bladder; closed rectal opening (imperforate anus); and other abnormalities of the lower gastrointestinal tract. The exact cause is unknown, but it is believed to result from irregularities in early development of the blood circulating system within the embryo. Surgery has been successful in separating joined legs. Other treatment is symptomatic and supportive.
What are the alternative names for Sirenomelia?
- Mermaid malformation
- Fused legs and feet
- Sirenomelia sequence
- Mermaid syndrome
What are the causes for Sirenomelia?
The exact cause of sirenomelia is unknown. Researchers believe that both environmental and genetic factors may play a role (multifactorial). Some cases are thought to result from irregularities in early development of the circulatory system, as some individuals with sirenomelia have a single large artery branching off of the aorta (instead of the usual two). Abnormalities in this blood delivery system decreases blood flow to the lower areas of the embryo, interfering with development. Some of the risk factors that have been identified in this condition include maternal diabetes, teratogens, genetic factors and maternal age younger than 20 years.