20/20 Friday: Life-Altering Experiences

Dec. 17, 2007 — -- Within hours of Katie Trebing's birth Dec. 12, 2002, she needed a blood transfusion to save her life — the first of many to come.

Steve and Stacy Trebing's daughter was born with Diamond Blackfan Anemia, a rare bone marrow disease that affects just 30 out of 4 million newborns each year in the U.S. and Canada. Stacy hasn't forgotten the day her pediatrician broke the news.

"I remember vividly being in his office, holding Katie, and him saying, 'OK, you're gonna be tied to hospitals for the rest of your life.'"

Katie's body wasn't making any red blood cells to carry oxygen to her organs, and never would. She needed transfusions every three to four weeks or she would die. But that treatment came with devastating side effects, drastically shortening Katie's life span. More than 40 percent of transfusion therapy patients die before they turn 40.

There was just one way to cure Katie — a bone marrow transplant from a perfectly matched sibling. Her older brother, Calvin, was not a match and the Trebings learned about a process of testing embryos called pre-implantation genetic diagnosis. The outcome would ensure their next child and Katie shared the same bone marrow DNA.

Some critics say PGD creates children for "spare parts." For Steve and Stacy, the technology meant a healthy sibling added to their family and the chance for Katie to have a normal life, but there was a dark side. A bone marrow transplant was a perilous operation: It would either cure their daughter or kill her.

Friday on "20/20" you'll see how far these parents were willing to go to keep their daughter from a lifetime of suffering, and the events that swayed their decision on whether to create the perfect sibling.

Also on the show, only in his mid-twenties, David Smith lived as a recluse. He weighed 635 pounds, didn't have a support system or close friends and was ready to kill himself — unable to withstand the pain of being mocked and taunted because of his size.

Smith was full of despair and had no hope, until he saw trainer and lifestyle correspondent Chris Powell on the television station KTVK in Phoenix and decided to e-mail him and ask for help. Surprisingly, Powell came out to meet Smith and together they embarked on the journey of a lifetime.