The article says that they did do this:

> Qiu’s team had engineered mice to have a human version of the CHD3 gene with their daughter’s mutation, R1025W, which results in a protein with the amino acid tryptophan where there should be an arginine. The mutant pups developed autismlike traits and didn’t squeak as much as normal mice when separated from their mothers. When the researchers repaired that mutation, the pups developed normally.