A disease or disorder with Siren in the name?

Its about the bones in your feet being grown together im pretty sure and the skin grows over them making a mermaid effect i'm not sure if its a disorder or disease or whatever. Does anyone know what its called?

A disease or disorder with Siren in the name?
Sirenomelia is a rare congenital disorder can result in a child with legs fused together and the genitalia reduced. Because of the similarity to the legendary mermaids, it is called "mermaid syndrome" or "sirenomelia". This condition is about as rare as conjoined twins and is usually fatal within a day or two of birth because of kidney and bladder complications. There are two known survivors of this disorder alive today.