Gene therapy shows promise against blood-clotting disease

Gene therapy has freed 10 men from nearly all symptoms of hemophilia for a year so far, in a study that fuels hopes that a one-time treatment can give long-lasting help and perhaps even cure the blood disease.

Hemophilia almost always strikes males and is caused by lack of a gene that makes a protein needed for blood to clot. Small cuts or bruises can be life-threatening, and many people need treatments once or more a week to prevent serious bleeding.

The therapy supplies the missing gene, using a virus that's been modified so it won't cause illness but ferries the DNA instructions to liver cells, which use them to make the clotting factor. The treatment is given through an IV.