By changing the DNA on two places, scientists have developed a super-muscled mouse, with four times the amount of muscle as usual.

The protein myostatine was already known to slow down the muscle grow. Animals and humans without this protein develop extra big muscle cords as well as a lot of muscle cords.
It is also known that the substance follistatine will slow down the development of myostatine, and thus create more and bigger muscle cords.

Researchers of the Johns Hopkins University have changed the gen for follistatine in a way that the mice produce extra of it, which results in heavy-muscled animals. The animals that were four times more muscled had both the gens for myostatine and follistatine changed.

The research can be interesting for diseases like Duchenne muscular dystrophy, were humans can, genetically, grow more muscles and thereby overcome the dystrophy.