Embryo screening for gender, diseases raises questions

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. But Tanya's first child was a son. Then came another. When an ultrasound showed that her third child was also a boy, she struggled to hide her tears from the nurse.

And that is why this year she drove 400 miles to a doctor's office in Los Angeles. Using methods common in fertility clinics, 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 had the DNA to become boys, and which were programmed to be girls.

The three male embryos were frozen, their fate to be decided later. The two female embryos were transferred to Tanya's womb in to create the daughter she always wanted.

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 - and which to reject as unhealthy, or merely undesirable. The cost is about $10,000, including the price of in vitro fertilization, the procedure that creates "test-tube babies" and which is a required part of embryo screening.

But as the number of doctors offering the service leaps upward, embryo screening is raising some profound questions: Is it proper to discard an embryo based on genes or gender? Which lives aren't worth living? Who decides? Some fertility specialists say the questions will only become thornier, as scientists are bound to create tests for disease as well as various traits.

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. By weeding out male embryos from the females, the doctors aimed to help parents avoid such gender-linked diseases as hemophilia and Duchenne muscular dystrophy, which are inherited overwhelmingly by boys.

Later techniques allowed doctors to screen for the genes that cause a variety of diseases. The screening, however, has become widely available only in the last two years, as more companies have begun handling the sophisticated laboratory work for fertility doctors.

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.