Caudal Dysplasia, also called Caudal Regression Syndrome, Caudal or Sacral Agenesis (e.g. Sirenomelia): This is due to mesodermal insufficiency in the caudal-most region of the embryo, which contributes to the formation of the lower limbs, urogenital system and lumbosacral vertebrae.
Affected child exhibits a variable range of defects including:
Hypoplasia and fusion of the lower limbs, vertebral abnormalities, renal agensis, imperforate anus, and abnormalies of the genital organs.
Caudal dysplasia or regression syndrome is associated with maternal diabetes in human.