The altered mice, it turned out, squeaked at a lower pitch than their un-humanized peers.

The researchers tested to see whether the altered mice cried out in response to other stresses like cold temperatures.

But the genetically altered mice become lost.

The hard part was getting the dams, the mother mice, to carry the altered mice to term.

Other approaches such as genetically altered mice should be developed and refined.

The altered mouse pressed 25 to 30 times.

In April, Harvard University received the first animal patent, on a genetically altered mouse.

The Patent Office has since used the ruling to issue a patent for a genetically altered mouse.

Although the genetically altered mice produced about 50 times the normal amount of the protein in their muscles, they suffered no ill effects, the researchers said.

Genetically altered mice lacking TPH1 develop progressive loss of heart strength early on.