Tetra-amelia is a very rare disorder that is characterized by congenital absence of all four limbs. Tetra-amelia is most commonly caused by teratogens. However, it can be also inherited.
It is thought that mutation in the wingless-type MMTV integration site family member 3 (WNT3) gene is responsible for causing tetra-amelia in humans. Moreover, studies showed that WNT3 gene not only plays an important role in early limb development, but also participates in the development of other organs.