When the Pittsburgh Steelers open the 2012 regular season Sunday night in Denver, one prominent member of the defense will not be on the field.  Starting free safety Ryan Clark has sickle cell disease, and playing in the high altitude of Sports Authority Field at Mile High can be dangerous.

The last time Clark played a game in Denver, in 2007, Clark ended up going to the hospital – losing his spleen, his gallbladder and the rest of the season.  But Clark is trying to turn a disappointing week into something positive through a new initiative called the “Ryan Clark Cure League,” which will raise money for sickle cell research and patient care.

Clark says the public education is not where it needs to be when it comes to sickle cell disease, but he’s working with Dr. Mark Gladwin of the University of Pittsburgh School of Medicine to change that.  “To be affected with it personally, through my own trials, I think you’ve finally found two people who have enough passion for it to get the word out.”

It’s hard for Clark to explain to people just how much pain he was in back in 2007, because the disease does not present itself visually.  “But your pain really is at a ten,” he says.

About 70,000 Americans have the blood disorder, because they’ve inherited two copies of the sickle cell gene.  It can cause pain, anemia or even death.