Embryo screening

November 25, 2002
http://www.knoxnews.com/kns/health_and_fitness/article/0,1406,KNS_310_156567 0,00.html
Which ones get to be born? Embryo screening poses questions beyond medicine
By Aaron Zitner, Los Angeles Times

LOS ANGELES - She had the name picked out since high school: Logann Rae, taken from a soap opera. She had two dolls waiting in a closet, both saved since childhood. Tanya had always dreamed of having a daughter and of the intimate bond that would grow as they picked out dresses together, styled their hair and painted their fingernails. Tanya's first two children were sons. When an ultrasound showed her third was also a boy, she struggled to hide her tears from the nurse.

This year at a doctor's office in Los Angeles, doctors mixed Tanya's eggs with her husband's sperm to create five embryos in a laboratory dish. Then, using a new technique, they examined the embryos to determine which would become boys. The three male embryos were frozen, their fate to be decided later. The two female embryos were transferred to Tanya's womb.

The embryo-sorting technique, called PGD for "pre-implantation genetic diagnosis," is quickly _becoming the most controversial development in high-tech reproduction. Doctors are able to screen embryos not only for gender but for whether they carry the genes involved in cystic fibrosis, sickle cell anemia and more than 100 other inherited diseases. They can even tell whether an embryo would grow into a good cell donor to help a sick person. The information is helping parents choose which embryos they want, which to reject as unhealthy or merely undesirable. It _costs about $10,000.

As the number of doctors offering it leaps upward, embryo screening is raising profound questions: Is it proper to discard an embryo based on its genes or gender? Which lives are not worth living? Who decides?

The debate has been building since the late 1980s, when doctors at London's Hammersmith Hospital learned how to tease a cell from a 3-day-old embryo and study its chromosomes for gender. They aimed to help parents avoid such gender-linked diseases as hemophilia and Duchenne muscular dystrophy, which are inherited overwhelmingly by boys.

Later techniques allowed _screening for the genes that cause a variety of diseases. The screening, however, has become widely available only in the last two years.

While no one keeps complete numbers, specialists say about 50 U.S. clinics now offer the service to patients. Nearly 2,000 embryo-screened babies have been born worldwide since 1992.

Embryo screening has caught the attention of Joy Pablo, 34, a Los Angeles nurse who has battled breast cancer since 1998 and worries that her 5-year-old daughter will one day face it.

"If they could guarantee me a boy, I would have peace of mind,'' said Pablo, "because the chances of breast cancer are so much smaller than with a girl.'' When having children, people often roll the genetic dice and hope for the best. Or they become pregnant and use a prenatal test, such as amniocentesis, followed by an abortion if the test turns up a problem. With embryo sorting, "they can start their pregnancy on Day One with a commitment to continuing it,'' said Dr. Mark Hughes of Wayne State University in Detroit, who helped develop embryo diagnosis with the Hammersmith doctors. "How can it be more ethically troublesome to test before a pregnancy than later, when the fetus has a heartbeat and is moving?''

Where amniocentesis usually provides information about a single fetus, embryo screening allows parents to judge and reject many potential children at once. Because it bypasses the pain of abortion, some fear it will be used too freely, coarsening attitudes toward the embryo. Germany has barred embryo screening for any purpose. In England, it can be used to select a child's gender only when there is medical need. In the United States, there are no restrictions on it.

"Morally reprehensible,'' said Dr. Robert E. Anderson of the Southern California Center for Reproductive Medicine in Newport Beach. "Most Americans, no matter where they come down on the question of where life begins, would find something morally objectionable about creating embryos and then discarding some simply because of their sex.''

Using embryo screening to detect disease also has drawn protest, as disease genes alone may not tell a whole story.

Embryo tests can detect the genes behind cystic fibrosis, for example, but not whether it will be so mild that symptoms are negligible, as sometimes happens. Some critics say it is immoral to reject a potential life on the basis of a disease that may turn out to be mild.