Fighting Disease With DNA

By the time Jacob Flood turned 2, his mother, Marla Flood, knew something about him was different.

(ABC News)

"It was pretty much said, you know, 'He's splitting off. He's splintering off, developmentally," Flood said. "'I think he has autism.' And, of course, mom didn't take that very well."

Watch the second part of the gene series tonight on "World News with Charles Gibson."

Within a year, Jacob was put on medication for his autism. But over the years, his behavior only seemed to get worse.

"He would get to the point where he was extremely physically aggressive towards myself, my husband, my kids. He would bite, pinch, pull hair. He would hit," Flood said.

Flood, her husband and other children ended up with bruises on their arms.

Prescribing the right drugs was a "guessing game," she said, because Jacob isn't able to communicate well. "He can't tell me when 'this medicine is making my body shaky, or it's giving me a headache, or it's making me feel like I'm going to throw up.'"

So, two years ago, Jacob's doctor tried something new and innovative. Jacob, who is now 11, was given a genetic test to find out how his body was processing the autism medicines he was on.

The results were startling.

"We realized we overdosed him," said Dr. Patty Manning-Courtney, of Cincinnati Children's Hospital Medical Center, "and he got worse, because we gave him too much of what we thought was a good thing."

'We Saw a Big Change'

Cincinnati Children's Hospital currently offers testing for two genes to all children and adults admitted to the hospital who receive psychiatric medicines.

The test involves gauging the way individual people's livers metabolize medicines.

And Jacob's mother said that while the new lower-dose prescription did not cure her son's autism, he's now a "different kid."

"We saw a big change. We saw less aggressiveness," Flood said. "He still screams, and he stills get mad, and he still has some aggressive behaviors, but they're nothing like they were before."