Sirenomelia

Sirenomelia alternatively known as Mermaid Syndrome is a very rare congenital malformation in which the legs are fused together to make the appearance of Mermaid's Tail.

This condition has been found in about one in 100,000 live births [1] (about as rare as Siamese twins), and usually die within a day or two due to complications of the birth of an abnormal kidney and bladder development and function. More than half the cases of sirenomelia result in stillbirth, and this condition is 100 times more likely to be identical twins than a single birth or twins. [2] This is due to the failure of the normal supply of blood vessels to lower aorta in utero. Mother's diabetes has been associated with caudal regression syndrome and sirenomelia, [3] Although this association is not universally accepted. [4]

VACTERL-H is an extended form of VACTERL association notes that this diagnosis is a milder form of sirenomelia. [5] disorder was previously thought to be an extreme example of Caudal regression syndrome, but it became regarded as a separate condition.