Embryo screening for late onset cancer is not frivolous

Whenever embryo screening is discussed in the media, there is always talk of slippery slopes and designer babies. And the most recent occasion should not disappoint. When Professor Joy Delhanty of University College London announced her plans to offer embryo screening - or preimplantation genetic diagnosis (PGD) - for a range of inherited cancers, there was a predictable cry of concern. Where will all of this end?

We've been here before. The first birth after successful preimplantation diagnosis was in 1989. At that time, there was much talk of slippery slopes. It was thought that PGD might start off testing for deadly genetic diseases which take effect in childhood, but it would not stop there. Soon, we would be designing our children by selecting for desirable characteristics such as intelligence and athleticism.

Ten years later, we do not seem to have slipped very far. After a small number of births, the handful of embryo screening programmes around the world are still offering testing only for serious genetic diseases such as cystic fibrosis and Duchenne muscular dystrophy. But some feel that testing is already getting frivolous. Preventing the birth of children who will quickly become ill and may die before adulthood may be acceptable, they say. But preventing the birth of those who may not become ill until much later in life is often viewed with suspicion. Worse still, critics say, is testing for a disease which not only has a late onset, but which may never appear at all.

The inherited cancers that Professor Delhanty is testing for fall within this category. But it is wrong to think that such testing constitutes a frivolous use of preimplantation genetic diagnosis. Those people born into a family blighted by an inherited cancer are not able to enjoy decades of life unaffected by the disease. Even if they never develop it themselves, or they develop it very late in life, they will be affected by the disease in other ways. Witnessing the deaths of other family members and wondering whether they will befall the same fate can be a very heavy burden to bear. A late onset disease imposes a psychological burden on families which can be almost as unbearable as the disease itself.

It's not unethical to offer such techniques to couples at high risk of passing on such a disease to their children. Rather, it would be unethical not to.