Public opinion in Britain is to be sounded out on a rapidly developing form of genetic testing which allows potential parents to discover whether an embryo carries serious hereditary conditions before it is implanted in the uterus.
Pre-implantation genetic diagnosis - or PGD - is used to help couples with serious genetic disorders in their family to have healthy children. But medical scientists acknowledge that people are concerned by the ethical issues involved.
The British public will be the first in the world to be asked its views thanks to a four-month consultation exercise staged by the Human Fertilisation and Embryology Authority and the Advisory Committee on Genetic Testing.
HFEA chair Ruth Deedes acknowledges that scientific and medical advances, especially in the field of genetics, often cause public unease, so 'we feel it's time the public had a say'.
The HFEA has already decided that PGD should not be used to test for social, physical or psychological characteristics, or for other conditions not associated with serious, often life threatening, medical disorders, she adds.
Concerns have been raised in the past that the use of PGD with pre-natal diagnostic tests is tantamount to saying that those affected by a particular condition should not have been born, or are less valued as individuals.
But the HFEA consultation document argues: 'To say that, given a choice, it would be better for a child to be free of a serious disease, does not necessarily reflect on attitudes towards people with that disease.'
PGD was developed in the 1980s and was first used successfully in 1990 to produce two sets of girl twins.
It is currently used to detect whether an embryo created through in vitro fertilisation has a genetic defect that will give rise to an inherited genetic disorder, such as cystic fibrosis.
It can also be used to determine the sex of an embryo where there is a risk of passing a serious gender-linked disorder, such as haemophilia or Duchenne muscular dystrophy, to a boy (see box, below).
Embryos that do not carry the genetic disorder or are not of the potentially affected sex can then be transferred to the uterus in the hope that a normal pregnancy will develop.
Many tests used in PGD are not new and are already used in pre-natal diagnosis tests, such as amniocentesis and chrorionic villus sampling.
But PGD means potential parents can begin a pregnancy knowing that only unaffected embryos have been transferred.
Although PGD has been small-scale so far, genetic testing is becoming more widely available and, as more people seek tests to establish whether they carry specific disorders, it may be that the demand will increase, says HFEA spokesman James Yeandel.
'The Human Fertilisation and Embryology Act allows for a line to be drawn permitting some activities and prohibiting others, ' he says. 'The consultation document aims to consult on whether, given the potential use of PGD, there are any uses which should not be permitted or which should only be permitted under certain circumstances.'
This is not the first time the HFEA has invited the public to comment on ethical issues. In 1993, following a consultation exercise that drew 200 responses, it banned IVF sex selection for social reasons but allowed its use for medical reasons.
NHS Confederation policy manager Tim Jones applauds the HFEA's decision to consult. He says: 'There are lots of issues in healthcare which are resolvable by science but some need a public debate on the ethical dimensions, too, and PGD is one of these.'
He hopes healthcare managers and commissioners will respond to the consultation document.
The Muscular Dystrophy Campaign and the Cystic Fibrosis Trust have also welcomed the exercise. 'We will be keen to study the findings of this consultation, ' says Tony Lee, executive director of the Muscular Dystrophy Campaign.
The Church of England board for social responsibility has been asked to comment, and says it will respond to the document when it has had a chance to consider it in detail.
Peter Warden, on behalf of Jehovah's Witnesses, says: 'We will have to apply our minds to see whether our belief in the sanctity of human life applies in this case as, obviously, an embryo is not viable until it is implanted in a woman's womb.
'This is new to us and we have not looked at the techniques involved.'
Genetic disorders and PGD
Cystic fibrosis, Duchenne muscular dystrophy, haemophilia, Huntingdon's disease, the thalassaemias, sickle-cell disease and a number of rare hereditary cancers are among the serious disorders caused by single-gene defects.
Around 20 of these disorders account for 70-80 per cent of all major genetic diseases in the UK. Two per cent of babies are born with a single-gene or chromosomal disorder, and in total, 3 per cent have some form of congenital malformation. For many affected couples there is a high risk that the condition will recur in their children.
Four UK centres are currently licensed for pre-implantation genetic diagnosis and one for carrying out the embryo biopsy part of the procedure only.
PGD depends on the success of in vitro fertilisation. But it does not guarantee that the treatment will result in a baby being born - the live birth rate per treatment cycle of IVF in the UK is 17 per cent. Around 20 babies have been born after 200 PGD treatments in the UK.
PGD is likely to be more expensive than standard IVF treatment. So access may be limited by the ability of patients to meet the costs or by the willingness of health authorities to fund Consultation Document on Preimplantation Genetic Diagnosis . www.hfea.gov.uk or www.doh.gov.uk/genetics/preimplant.htm