The Food and Drug Administration (FDA) has approved an Rx called ATryn, which is made from goats genetically altered to produce the blood-thinning protein antithrombin.

ATryn has been okayed for use by people with a condition called hereditary antithrombin (AT) deficiency that puts them at increased risk of developing clots in their legs and lungs during childbirth and surgery. One in 5,000 people in the U.S. have AT, according to the FDA.

"The approval of ATryn marks a significant milestone in the development of this innovative recombinant technology and delivers a new therapeutic option,” Geoffrey Cox, chairman and CEO of Massachusetts biotech GTC Therapeutics, said in a statement.

Environmentalists had opposed the move, saying there wasn’t enough proof humans would be safe if milk, cheese or meat from the genetically engineered goats were to get into the food supply. The goats produce large amounts of antithrombin thanks to recombinant DNA (rDNA construct), a segment of DNA that is introduced into their genes to manufacture the protein.

Though GTC has said it has mechanisms in place to prevent the goats from ending up on your dinner plate, "humans are fallible and accidents do happen," Gregory Jaffe, director of the Center for Science in the Public Interest's (CSPI) Biotechnology Project, tells "Even if they're not intended to end up in the food supply, many things do end up in the food supply. FDA should have taken a look at what would happen if [consumers] ate the food and drank the milk."

Bernadette Dunham, the director of the FDA's Center for Veterinary Medicine, said genetically altering the goats did not appear to affect their health or ability to successfully mate. “We have looked carefully at seven generations of these GE goats; all of them are healthy and we haven't seen any adverse effects from the rDNA construct or its expression," Dunham said in a statement.

We have a more in-depth look at ATryn and an explanation of why goats could make good medicine in two pieces from the September 2006 issue of Scientific American.

Image of goat © iStockphoto/Global Photographers