A mutation in the WNT3 gene has been shown to cause Tetra-Amelia Syndrome [TAS] among members of one large family from Turkey. This mutation, which occurs in both copies of the WNT3 gene in each cell, replaces one protein building block (amino acid) with a premature stop signal in the instructions for making the WNT3 protein. This mutation is written as ‘Gln83Ter or Q83X’.
Researchers believe that the Gln83Ter mutation results in the production of an abnormally short, nonfunctional version of the WNT3 protein. Loss of the WNT3 protein disrupts normal limb formation before birth and leads to the other serious birth defects associated with Tetra-Amelia Syndrome [TAS].