Imagine tripping over your feet during a leisurely stroll down the sidewalk. Ouch! Your knees are scraped below your shorts and blood starts to drip. A quick wipe from a conveniently pocketed napkin and soon enough, you are the proud owner of some new scabs. Life goes on.
If you are one of the 20,000 Americans with hemophilia, this story has a much different ending. Hemophilia is a condition which prevents scabs from forming due to a lack of functional blood clotting factors. You would need to start replacement therapy right away, or the bleeding could last days, weeks, or even lead to death.