For example, scientists had predicted that more primitive animals such as fish would be missing certain blood-clotting proteins.

The company recently announced a cross-licensing agreement with Genentech Inc. for genetically engineered Factor VIII, a blood-clotting protein for hemophiliacs.

The biologists are attempting to treat the animals by supplying their muscle cells with the gene that makes Factor VIII, the blood-clotting protein missing in many human hemophiliacs.

Coagulopathy may be caused by reduced levels or absence of blood-clotting proteins, known as clotting factors or coagulation factors.

Doctors have successfully used gene therapy to treat a form of hemophilia, they reported yesterday, injecting patients with a gene that produced a blood-clotting protein without adverse side effects.

The gene, known as F13B, codes for part of Factor XIII in the cascade of blood-clotting proteins.

Speywood has a world lead in developing a blood-clotting protein that could change the lives of thousands of haemophiliacs.

Genetics Institute, a biotechnology company based in Cambridge, Mass., is best known for a genetically engineered replacement therapy, sold as Recombinate, for the blood-clotting protein that hemophiliacs lack.

The results, which produced a blood-clotting protein without adverse side effects, were reported in research connected with hemophilia B, which affects about 5,000 Americans, or 20 percent of all hemophiliacs in America.

It involved six patients with severe hemophilia A, a disorder caused when the gene for a blood-clotting protein, Factor VIII, fails to function.