National genetic screening programmes are needed

Press coverage of a report recently published by the Advisory Committee on Genetic Testing (ACGT) on the subject of Prenatal Genetic Testing suggests that a radically new service is being proposed, involving the 'mass genetic testing of pregnant women' with the attendant risk of a slippery slope towards the creation of 'designer babies'. Is this the usual hype and scaremongering? On the whole, yes. But there is something real to cover, and discuss.

The ACGT, by and large, describe best practices as they currently exist and, reasonably enough, suggest that these should be adopted nationally. As their report notes, genetic testing is now a well-established part of antenatal care, which may benefit a number of different groups of pregnant women, including: those with a high risk of carrying an affected pregnancy, indicated by family history; those with a low risk, but who have a child with a condition and seek reassurance about the current pregnancy; those at increased risk without a family history (such as age-related risk for Down syndrome); and those for whom routine scans turn up a problem with the fetus that may be due to an underlying genetic disorder.

Given the rarity of serious genetic conditions, the development of the service on the above basis, even in the light of new genetic knowledge, will not lead to the feared testing of all pregnant women. But the report does contain an important suggestion that should be considered seriously - not the testing of all pregnancies, but the offer of a test to all pregnant women, or a large subgroup of them, 'with the aim of identifying those at higher risk so that more specific tests may be offered'. As they note, the National Screening Committee should consider such programmes.

The number of conditions for which this might be considered would be small. For the population as a whole, cystic fibrosis is the obvious example; for particular ethnic groups thalassaemia. The crucial feature of these conditions is that if both parents are carrier they are at a one in four risk of producing a child with the condition. And yet they may well be ignorant of this fact because they are unaffected themselves and without any known family history. The rationale for screening the parents to see if they are carriers, with the offer of testing the fetus if this is the case, is then clear. Where screening programmes of this type do exist and are well organised, the uptake rate is generally high, indicating that they satisfy a genuine need. Accordingly, as Modell and colleagues point out in their study of screening services for thalassaemia during pregnancy, the fact that well-organised programmes do not exist on a national basis means that families are being denied the chance to make an important choice.

John Gillott is policy officer at the Genetic Interest Group