When one considers the genuine suffering caused by breast cancer, categorising 80 per cent as 'reduced' penetrance (rather than 90 per cent) may be hair-splitting. While both breast and colon cancer are treatable, this is not always so and many treatments fail. Moreover, other diseases for which PGD is already licensed (including cystic fibrosis) can be managed or treated. What all the disorders so far considered have in common is that none is curable. Much of the serious debate has centred on the issues of risk or severity of disease and attitudes to risk. On these issues, responses from the public consultation document: PGD: Choices and Boundaries (HFEA, 2006), tell us what we already knew: individual attitudes toward risk and what is considered 'serious' disease are subjective and vary widely. Fortunately, the HFEA Ethics and Law Committee concluded that despite being treatable, later-onset and reduced penetrance, inherited predispositions for breast and colon cancers may still be considered 'serious' genetic conditions.
One surprising, and welcome, finding from the consultation document was that more than half of all 283 respondents were still at school, perhaps demonstrating that many different stakeholders are taking ownership for important ethical issues impacting society. Despite the enormous range of opinion, respondents appeared to agree on two issues: (i) that penetrance alone should not dictate which tests could be offered and (ii) the availability of PGD should not be determined by current practice in prenatal diagnosis.
PGD offers the choice for individual patients at risk of transmitting genetic disease to help prevent suffering for their families. PGD has never been about discrimination against people with genetic disease, cancer or disabilities. Neither should PGD be viewed as obstructing or removing the need for research into developing cures for genetic disease. Indeed, the production of embryonic stem cells from embryos carrying disease mutations, diagnosed using PGD, may actually accelerate progress towards a cure (References 2-4).
What about 'designer babies'? The phrase is just too tempting to resist and unfortunately has entered the media lexicon. In reality, our choice of reproductive partner is the closest most of us will ever get to designing babies. Moreover, a simple thought experiment may help to alleviate fears that PGD will soon be used to design babies with selected positive traits such as intelligence. Suppose that only five genes code for intelligence - in fact, there may be hundreds - with each gene having a high and low performing allele (version). To get the desired combination of high intelligence alleles in just one baby, more than 5000 embryos would need to be tested. It would take a woman 40 years of continuous IVF with PGD to achieve this. In short, 'designing' babies using PGD is a non-starter.
Despite some high-profile opposition, PGD has already helped thousands of families with hundreds of different genetic problems. Such problems, if ignored, would lead to enormous suffering for children and their parents. IVF treatment (especially when combined with PGD) demands considerable physical, emotional and financial investment from couples courageous enough to choose this option. We should be confident that fully informed patients working together with their doctors will make sensible choices regarding the use of PGD to help them to have healthy children.