PHG Foundation

In this procedure, embryos produced by in vitro fertilisation are biopsied by removal of a single cell which is tested for a specific genetic characteristic, usually a disease-causing mutation for which the family is at risk. Only an embryo or embryos that are free of the mutation are implanted in the mother's uterus.

Because PGD involves the manipulation of human embryos, it comes under the provisions of the 1990 Human Fertilisation and Embryology Act and is regulated by the Human Fertilisation and Embryology Authority, a statutory body established by the Act.

The HFEA licenses clinics to carry out PGD for specific conditions, basing its decisions on the guidance in its current Code of Practice. This says that PGD should be made available 'only where there is a significant risk of a serious genetic condition being present in an embryo'. To date almost all PGD licences have been granted for couples at risk of having a child with a life-threatening genetic disease such as cystic fibrosis.

Now the HFEA wants to know what the public thinks about the use of PGD for 'lower penetrance' conditions such as inherited susceptibility to breast cancer. The term 'lower penetrance' means that the probability that a person carrying a mutation will be affected by the disease is significantly less than 100%.

For example, in the case of a family with inherited susceptibility to breast cancer associated with a mutation in the BRCA1 gene, a family member carrying the mutation has a 60-80% chance of developing breast cancer by the age of 80. Mutations causing a similar level of risk are also known for a type of inherited susceptibility to bowel cancer.

Should the HFEA license a clinic to use PGD to test a couple's embryos for such mutations? It's a difficult question. In contrast to, say, cystic fibrosis or Duchenne muscular dystrophy, breast and bowel cancer do not generally develop until adulthood and various treatment and surveillance options are available to those known to be at high risk. Another consideration is that PGD itself is a difficult procedure that is expensive and carries all the risks associated with IVF.

On the other hand, the HFEA's Code of Practice states that the views of the couple seeking treatment should be taken into account when a licence application is assessed, and that the indications for the use of PGD should be consistent with (though not necessarily identical to) current practice in the use of prenatal diagnosis.

There appears to be very little, if any, current demand for antenatal diagnosis of inherited cancer susceptibility mutations, but if couples felt strongly enough to want to go down this route then it is unlikely that it would be illegal under the current abortion legislation, at least if any termination were carried out within the current 24-week limit. Perhaps, then, the views of the couple concerned should also prevail in decisions about PGD.

The HFEA considers that it has a duty to strike a balance between the wishes of couples seeking treatment and the views of wider society. Key questions in its consultation include:

Is inherited susceptibility to cancer a 'serious genetic condition'?

What is the lowest penetrance that might be considered to confer a significant risk of disease?

How much weight should be placed on the views of people seeking treatment?

Where should the limits of PGD lie?

Anyone wishing to respond to the consultation has until 16th January to do so. A concise background paper setting out the issues, is available on the HFEA website at http://www.hfea.gov.uk/AboutHFEA/Consultations


Dr Alison Stewart is Chief Knowledge Officer at Cambridge Genetics Knowledge Park.


January 2006


Biolines is a monthly biotechnology column emphasising legal, ethical and social issues.