Specialty pharmaceutical company Biovitrum of Stockholm, Sweden said today that it has begun human clinical tests of its new anti-hemophilia drug, a recombinant form of a blood-clotting protein called Factor IX that it is developing in collaboration with Waltham, MA-based Syntonix. The company said it had initiated dosing studies of the drug on patients with Hemophilia B, a hereditary condition in which patients lack Factor IX.