• Dakota's Dream Video
• Definition of Stem Cells
• Article: Stem Cells Could Halt Tay-Sachs Damage
• Informative Links

Posted on Sun May 21 21:47:07 2006 by Coleus

Even before her first birthday, Jashaia Trinity Small startled more easily than other children exposed to loud noises. Once an ambitious walker, she began to fall more often and needed support to stand up. She blinked repeatedly, "and when you called her, she had to look around the room to see where you were," her mother, Nadine Green-Small recalls."By the time she was a year and a half, I knew something was really not right," Green-Small said.

Last fall, Jashaia Small was diagnosed with Tay-Sachs disease, a genetic disorder most often diagnosed in eastern European Jews and only rarely in African Americans like Jashaia. The prognosis is the same for children in all ethnic groups who develop the disorder early in life: a progressive deterioration of neurological functions, including the loss of vision and mobility, and then death, usually by age 5.

In November, her parents took Jashaia to Duke University in desperate search for a treatment. After two months of evaluation, doctors gave her a transplant of umbilical cord blood, a promising source of potentially life-saving stem cells. The hope is that the stem cells will at least halt the damage caused by the buildup of fatty material in her brain.

As Jashaia's family struggles to maintain hope, they also now accept that there is a limit to medical science's ability to deliver miracles. "They hope that they caught it early enough to make some difference, but they really don't know," Green-Small said. Now 21/2, Jashaia Small fell victim to a cruel genetic twist. In order to develop Tay-Sachs, both parents must carry a copy of a recessive gene that renders the brain incapable of breaking down a fatty material called ganglioside GM2. Even then, there is only a 1-in-4 chance their baby will develop Tay-Sachs.

There was no reason to suspect that young Jashaia was at risk. Green-Small and her husband, Dyvon Small, have two other children together, Zahkya, 8, and Journai, 6, who are free of the disease. The disease is very rare in African Americans. One of every 30 Ashkenazi Jews carries a copy of the recessive gene, and genetic screening for the disease is now common prior to Jewish marriages. French Canadians, Amish in Pennsylvania and people from the Louisiana bayou also have an increased risk of the disorder. While the Small family is aware of some white ancestors and some relatives from Louisiana, Nadine said almost all of her side of the family is from the West Indies, and she has no known relatives from high-risk groups.

Infantile Tay-Sachs is by far the most common form of the disease, but Jashaia developed symptoms late enough to be diagnosed with the rarer juvenile form of Tay-Sachs. Her doctors could offer little in the way of treatment. Jashaia's neurologist did mention that researchers at Duke University Medical Center had begun experimental procedures to see if transplants using umbilical cord blood could help stop the progression of Tay-Sachs. Cord blood is a rich source of stem cells and has shown promise in treating several diseases. Stem cells from bone marrow have been used for decades to treat leukemia, and more recently, oncologists have also been using cord blood for the blood cancer.

That's because stem cells in cord blood have some advantages over those harvested from bone marrow, said Dr. Suhag Parikh, a pediatrician in the blood and bone marrow division of the Duke University Medical Center. Stem cells in umbilical cord blood are less mature and tend to adapt more readily to new hosts than bone marrow stem cells, usually donated by adults, he said. Only about 30 percent to 40 percent of potential bone marrow recipients find a donor with a close enough genetic match for a successful transplant. With cord blood, however, 90 percent of potential transplant patients can be matched, he said. The greater ease in finding genetic matches is valuable for minorities, who are underrepresented on bone marrow registries and, therefore, less likely to find matches.

Cord blood cells, however, are expensive - at least $25,000 per transplant unit. Cord blood does not usually generate enough new cells to treat adults, who require multiple units of cord blood, he said. The use of cord blood to treat Tay-Sachs is relatively new and experimental. By the time Jashaia was referred, Duke had treated only a handful of Tay-Sachs patients. Duke had achieved some success extending the lifespan of children with another fatal disorder called Krabbe disease. Children with Krabbe disease lose motor function and often die before age 2.

Duke researchers found that cord-blood transplants weren't a cure for Krabbe. The transplants did block progression of the rare brain disorder but did not restore function already lost to it. The experience with Krabbe patients made it clear that the earlier in life cord-blood transplants could be done, the greater the potential benefit. Early results with Tay-Sachs patients showed the same pattern. Green-Small said Duke doctors told her before the transplant that, in the best-case scenario, Jashaia's symptoms would stop getting worse. That might mean she would be blind and unable to walk or talk.