Genetic testing is a way for doctors to use in-vitro fertilization to screen embryos for genetic diseases. But in the case of one family from Colorado, it is a way to have a baby that is not only healthy but also a suitable donor for bone marrow transplant.
The parents of Adam Nash are hopeful that the blood cells from his umbilical cord will save the life of his sister Molly who suffers from an often fatal genetic disorder. Dr. John Wagner is a cord blood specialist with the University of Minnesota, he talks to us about how a high-tech procedure called pre-implantation genetic diagnosis, enables a newborn boy to save the life of his ailing six-year-old sister.
It's the first time genetic testing was used by parents to have child who is not only disease free but also a suitable donor for an ailing sibling. Six-year-old Molly Nash has a fatal genetic disorder, Fanconi-anemia. It's a progressive disease for which the only proven therapy is a bone marrow transplant.
Molly's parents wanted more children. So, they decided to use a new procedure called pre-implantation genetic diagnosis to have second a child who would be both free of Molly's disease and become a suitable bone marrow donor. They succeeded. One month ago, Adam Nash was born. Later this month doctors at the University of Minnesota will use blood cells from his umbilical cord to replace Molly's defective marrow. The treatment will give Molly an 85% chance to beat the disease. It's a technique that raises many ethical questions. But as Molly and Adam's mother Lisa puts it, "we wanted a healthy child and it doesn't hurt him to save his sister's life."
What is pre-implantation genetic diagnosis
PGD--pre-implantation genetic diagnosis, starts with in-vitro fertilization, in which the mother takes drugs to generate several eggs at once, which are then fertilized by her husband's sperm. One cell is removed from each embryo and its DNA is examined for chosen genetic traits. Only the embryos that are free of the disease and are good tissue matches are implanted in the mother's uterus.
The perfect match
Adam Nash's embryo was chosen from among six last December because he was free of the genetic mutation that leads to Fanconi anemia, the disorder his sister Molly has. Because he was a good genetic match for his sister Molly, Lisa, underwent in vitro fertilization. Doctors at the Reproductive Genetics Institute in Chicago performed a pre-implantation genetic diagnosis on the embryos when they consisted of just eight cells to determine which were free of the disease.
"We could not knowingly bring a child into the world with that disease," says Lisa Nash
Fanconi anemia is a rare disease afflicts only about 1,000 people in North America although one in 200 carry the gene. In Jews of Eastern European descent, one in 80 may carry the gene. Molly was born without thumbs and without hip sockets--conditions typical of the disease. She also has gastrointestinal problems. Fanconi anemia leads to an inability to produce bone marrow, which leads to leukemia and death. It's estimated that 98% of all victims suffer from bone marrow failure by age 35, and half of them suffer from the failure by age seven.
The prognosis for Molly
According to Dr. John Wagner, the survival rate after a blood marrow trnsplant is 31% if the cells come from an unrelated donor and 85% if the cells come from
a sibling. Molly is scheduled to undergo the umbilical cord blood transplant later this month.
A report by the American Association for the Advancement of Science, the world's largest federation of scientists with more than 146,000 members, says that it is dangerous and irresponsible for scientists to experiment with genetic changes that will affect future generations of humans, even if the goal is to cure disease or create improved children. It recommended a public committee to monitor and oversee the increasingly sophisticated research into genetic modification. ©MMII CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed
Sondra Wheeler, a teacher at the Wesley Theological Seminary in Washington, says that permitting IGM, or inheritable genetic modification research in humans also could be socially disruptive. Wheeler spoke of the possibility that genetic changes that produced healthier and improved children would be available only to the wealthy. "This would widen the gap between the `haves' and the `have-nots' to an unprecedented extent," says Wheeler.
Some critics fear parents will seek to give their offspring some competitive advantage, whether it is intellectual, athletic or otherwise. They are concerned that parents will feel compelled to take similar steps, not because they think it's a good idea, but because they fear their children will be at a disadvantage.
©MMII CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed