Sirenomelia, alternatively known as Mermaid Syndrome, is a very rare congenital deformity in which the legs are fused together, giving them the appearance of a mermaid’s tail.

This condition is found in approximately one out of every 80,000 live births (about as rare as conjoined twins) and is usually fatal within a day or two of birth because of complications associated with abnormal kidney and urinary bladder development and function.

More than half the cases of sirenomelia results from a failure of normal vascular supply from the lower aorta in utero.

Only a handful of patients who did not have the usual kidney and bladder complications have survived beyond birth with this condition, 3 of them being: Shiloh Pepin, Tiffany Yorks and Milagros Cerron.