5 children created to donate stem cells

Science: In a first, researchers screened embryos from lab to ensure transplants for ill siblings.

May 05, 2004|By Erika Niedowski | Erika Niedowski,SUN STAFF

Building on the high-tech science that lets couples choose their babies' sex or screen for genetic disorders, researchers are reporting the birth of five children from embryos created in a lab so they could serve as cell donors to seriously ill siblings.

Scientists at Chicago's Reproductive Genetics Institute say this is the first time that embryos have been screened solely to ensure that the baby could donate life-saving stem cells to a brother or sister in need of a transplant.

Yury Verlinsky, the institute's director, said that all the babies were born healthy and that the single transplant that has taken place was a success.

The research, reported in today's Journal of the American Medical Association, will likely add fuel to the debate over the ethics of conceiving a child for use as a donor as well as creating so-called "designer babies." Though genetic testing of embryos is generally accepted for preventing the birth of a child with a debilitating disease, the same screening for other purposes is far more contentious.

"It does sort of verge on the horrors of cloning and the horrors of selective breeding for particular characteristics," said Dr. Georgia B. Vogelsang, professor of oncology at the Johns Hopkins School of Medicine.

"Even if you say - and I absolutely agree - this [selecting for donor compatibility] is completely benign, where do you then draw the line once you start doing things like this?" she said. "Is it OK to - if there was a genetic marker - pick the embryo with the highest IQ?"

Screening embryos for tissue type is largely unregulated in the United States. The American Society for Reproductive Medicine has taken no position on it, though the group does support screening to prevent disease as well as to "balance" the gender makeup of a family - after the birth of a first child.

The research reported in JAMA involved nine couples with children suffering from leukemia or another blood disorder in which the bone marrow doesn't produce enough red blood cells. All the children potentially needed a stem cell transplant, using a donor of the same human leukocyte antigen type.

Antigens are proteins on the outer surface of every cell that tell the immune system whether the cell is considered friendly or an invader. In the best transplant match, six specific HLA markers are the same.

The couples requested the genetic testing after learning of it from a physician or on the Internet. Between 2002 and 2003, scientists at the institute created 199 embryos using in vitro fertilization, then removed DNA to screen for HLA genes. Forty-five of the embryos were an HLA match, and 28 were implanted. Five women became pregnant.

When the babies were born, doctors collected blood from the umbilical cord because it is rich in stem cells, which give rise to white and red blood cells and platelets. Stem cells are often used to treat cancers, such as leukemia, as well as immune or genetic disorders.

In one case, the harvested stem cells were transplanted into the sick sibling, who no longer needs red blood cell transfusions, the study said. Another child is preparing for a transplant, Verlinsky said, while the rest are in remission.

The Chicago institute, which funded the research, is a leading institution in the field of reproductive genetics and has a large in vitro fertilization program. In 1994, it was designated as a Pan American Health Organization/World Health Organization Collaborating Center for Prevention of Genetic Disorders.

Dr. Anver Kuliev, director of that center, said all the parents wanted another child, separate from the hope that the baby might serve as a donor.

"We respect this," said Kuliev, who took part in the research. "You are going to do everything you can to save the [sick] child."

That's what Abe and Mary Ayala did more than a decade ago. In a highly publicized case, the California parents conceived of a child in hopes that it could save their 16-year-old daughter Anissa, who had leukemia and desperately needed a bone marrow transplant.

Unlike the parents described in JAMA, the Ayalas were not guaranteed that the baby would be a match. Siblings have a one in four chance of being tissue compatible, compared to about a one in 20,000 chance with unrelated donors.

The story ended triumphantly for the Ayalas with the birth in 1990 of Marissa, who had the same HLA type as her sister and who later donated bone marrow that saved her life. But some medical ethicists and others sharply criticized the family for bringing a child into the world for a utilitarian purpose.

Times have changed - somewhat. In a survey last month by Johns Hopkins' Genetics and Public Policy Center, 61 percent of 4,005 respondents said that they approved of genetically screening embryos to select one that could help an ailing sibling. But nearly as many - 57 percent - said they would not approve of the same technique to select a child's sex.

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