FDA Approves a Genetically Engineered Drug

The first human drug produced by livestock genetically engineered to contain a human gene has now been approved by the Food and Drug Administration. A company called GTC Biotherapeutics developed a herd of goats (Figure 20.10 of Human Biology) that contain the human gene for antithrombin III, a protein used to prevent blood clots in people with hereditary antithrombin deficiency. One advantage of using farm animals is that larger quantities of human proteins can be obtained from the milk of genetically engineered animals than from human blood. One of GTC’s goats, for example, can produce as much antithrombin/year as the amount that can be extracted from 10,000 gallons of human blood!

How did GTC manage to get the antithrombin to be produced in milk, so they could harvest the protein by milking the goats instead of bleeding them? Simple concept, really - they linked the human gene for antithrombin to a goat gene for a milk protein.