Krystie Karl-Steiger’s fathers take turns running her to therapy and count the days since her procedure.

"This is the 198th day since her transplant. On the 193rd day she smiled," Rick Karl said.

It's a major milestone for 22-month-old Krystie, who was born with Tay-Sachs disease. That means she’s missing an enzyme that eliminates waste from her brain cells. It's a rare genetic disease that always ends in death.

"We talked to doctors back home. They said nothing we can do -- make her comfortable. We said we have to do more for her," Bruce Steiger said.

Their effort led them to the University of Minnesota Children's Hospital-Fairview, and to groundbreaking research.

"Bone marrow transplant using stem cells from umbilical cords, using a technique to prepare the body for transplant that we felt was less toxic," Dr. Lawrence Charnas said.

Blood tests show Krystie is now producing that critical enzyme.

"There is no guarantee this is going to work by any means, but at least there is hope it might," Steiger said.

They had a similar hope when working with surrogates and egg donors to get Krystie. They now see their little girl as a pioneer.

"If that test helps other kids, and it should, then I think Krystie's brought a lot to the world," Karl said.

Krystie's parents point out that she'll never be normal, but that she’s playing an important role in finding a cure.

 More information on Tay-Sachs