You Be the Doctor: What's Making Evan So Sick?

"Dr. Akhter gave us the diagnosis of CGD. Yet, I have a son who's still lying in a hospital bed in critical care," Teresa said. "I felt as though he wasn't going to make it at this point."

(ABC NEWS)

"We're treating him, but it looked like he was still getting worse," Akhter said.

Doctors decided that because the white blood cells weren't working, they'd try giving him a white blood cell transfusion.

"After laying there for a month lifeless, suddenly, he started to try to open his eyes," Keith said. "Once he started responding to the treatments, Evan recovered pretty rapidly."

Evan will always need medicine for his white blood cells, but now he's playing with his twin sister again.

"Evan is jovial. And funny," Teresa said. "Looking at him, you would never know what Evan experienced. What he went through."

So if you chose option C: Genetic Disease, you were right. Evan has CGD, a genetic disorder of the immune system, which allowed a host of infections to invade his body.

For more information about CGD, visit http://cgd.cultivatecommunity.com and http://www.cgd.org.uk/.