From Science News online -
A human version of a stretch of DNA, when inserted into a mouse embryo, cranks up the activity of genes in the developing thumb (shown blue).
Like electrical wiring in a house, genes may be turned on in many places at once, even though they might only be needed in one area, such as the eye, comments Francesca Mariani of the Broad Center for Regenerative Medicine and Stem Cell Research at the University of Southern California,. So while the new study can’t say what these regulatory changes might do in a human embryo, “this does show how a few small changes could make a big difference” she says. “The thing that is intriguing about this is the direction it could go.” - (emphasis mine)
Intriguing is not the word I would use. Something more like "appalling" or "horrifying" would be better. What these researchers don't perhaps appreciate is that they have no idea of "the direction(s) it could go", once others far separated in time and culture get to take charge of it.
I'm creating a whole new post category just for this kind of thing. Bad science... not poorly done science, but stuff that just shouldn't be done. Mixing human and animal DNA to see what happens is a big one.