GTC Biotherapeutics, Inc. is engaged in the development and production of human therapeutic proteins through transgenic technology that enables animals to produce a recombinant form of a specified human protein in their milk. Using this technology, the Company is developing a portfolio of recombinant blood proteins to treat a range of genetic and acquired blood deficiencies, including hemophilia and other blood coagulation disorders. These blood proteins, also known as plasma proteins, are difficult to produce in other manufacturing systems, and some are only available by extraction from human blood. It has also initiated the development of a portfolio of monoclonal antibodies (MAb’s), for use as potential follow-on biologics targeted at several market products. Its first product ATryn, its recombinant form of human antithrombin, a blood protein with anticoagulation and anti-inflammatory properties.