* Should scientists and doctors be allowed to screen embryos for genetic defects?; * Will screening eventually lead to embryos being destroyed because they are at risk of 'minor' disorders such as myopia or low IQ?

Tom Shakespeare, research fellow in the disability research unit, Leeds University, was born with achondroplasia, a genetic condition that restricts growth. The condition affected his father and affects his children.

"It is wrong to assume that particular differences are always tragic. The history of genetic medicine is that if (a treatment) is not possible we go on until it is.

People will eventually be divided into those who can afford genetic treatments for their unborn children and those who can't. I would challenge the division of genetic selection between diseases and 'normal' attributes. The reason disability isn't favoured is a social one."

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Michael Jarmulowicz, consultant pathologist at the Royal Free Hospital, London and secretary of the Guild of Catholic Doctors.

"I believe that life starts at conception, even if conception was in a petri dish. Early diagnostic testing was for disorders such as Duchenne muscular dystrophy where children are confined to a wheelchair and die in their mid-teens. One can almost sympathise with this.

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Doctors now screen for different disorders. We have testing for cystic fibrosis. This starts in childhood, and 20 years ago people affected by it would die in their late teens. Now medicine has advanced and people survive into their thirties and beyond. Cystic fibrosis could be fully treatable within the next 20 years.

Doctors also say let's test for forms of breast cancer with a high genetic incidence. But the test does not say you will definitely get the disease, it says there is an 80 per cent chance you will get it over your lifetime. I am even more unhappy than I was with the process because people are looking at genes that have only a statistical probability of causing a disease.

Recent research in Nature said that a gene had been identified for physical fitness. As the Human Genome Project advances, more genes will be identifiable that govern traits such as intelligence or height. We are beginning to realise that these characteristics are not as multifactorial as we thought."

Richard Nicholson, editor of The Bulletin of Medical Ethics.

"It is a sliding scale. It depends on the severity of the genetic disorder. If pre-implantation diagnosis can prevent muscular dystrophy, it may be suitable for some people.

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I would be hesitant in allowing testing for Down's syndrome. A lot of Down's people have a life with which they are perfectly content. They can reach a potential previously unthought of; it's not unusual to find Down's children going through the normal school system. However, the medical profession can be old-fashioned - many doctors still regard the birth of a Down's child as a bleak prospect.

I think it unlikely that testing will ever be carried out for lesser disorders such as myopia because the IVF process is so costly and time-consuming."

Christine Godsen, professor of medical genetics at Liverpool University and member of the Human Fertilisation and Embryology Authority, which is preparing a document for public consultation on pre-implantation genetic diagnosis.

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"For couples who have, say, a 25% genetic risk of having a child with a disorder and who have already had one or two terminations, I think pre-implantation genetic diagnosis is better than termination. You have not created a life so you are not ending it.

There have been fewer than 200 PGD pregnancies world-wide - for people who already have a terrible and intimate knowledge of disease. In the US they have changed the law so that life insurance companies cannot discriminate against those with disabilities. In the UK there is no such legislation. People with severe disorders can find it hard to get jobs, mortgages and life insurance.

It is responsible to want to have a healthy child. PGD should be seen as a step forward. Last year in Britain 180,000 terminations were for social reasons. Only 2,000 were for foetal abnormalities."

Some of the above spoke at a debate, "Babies by design?", last Friday at the Olympia Exhibition Centre, London organised by the Wellcome Trust.

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