A single genetic error can stop blood from clotting

Hemophilia was once a medical mystery described simply as a 'bleeding disease,' but today, doctors can scan 1.8 million genetic markers to find the exact error responsible. In about 45% of severe cases, the culprit is a massive flip in the genetic code known as an inversion, which halts the production of a vital protein that acts like biological glue. Without this protein, even a minor internal bruise can become a crisis because the blood's clotting activity drops to nearly zero.