Hemophilia B is an inherited sex-linked, blood-clotting disorder, which primarily affects males, and is caused by defects in the Factor IX gene. Hemophilia B affects about 3,300 people in the United States. People with Hemophilia B can experience repeated episodes of potentially serious bleeding, mainly into the joints, which over time can destroy the joints.
Alprolix was approved to help control and prevent bleeding episodes, manage bleeding during surgical procedures, and prevent or reduce the frequency of bleeding episodes (prophylaxis). Alprolix consists of the Factor IX molecule linked to a protein fragment, Fc, which is found in antibodies and makes the product last longer in circulation.
 FDA News Release, "FDA approves first long-acting recombinant coagulation Factor IX concentrate for patients with Hemophilia B," March 28, 2014.