A furore has developed over the ethics of creating "designer babies" ahead of new UK guidance on use of genetic screening techniques.

Dozens of couples in the UK have opted for preimplantation genetic diagnosis (PGD) to avoid giving birth to children with serious genetic disorders such as cystic fibrosis and haemophilia.

But revelations that the technique has allowed a US couple to create a baby to act as a donor to save his sister from a life-threatening disease has led many commentators to ask where the line will be drawn.

Click here to read full details of the Nash family's actions

Baby Adam Nash is free of the genetic disease Fanconi anaemia carried by his parents and is a perfect tissue match for his sister Molly.

The techniques used to produce baby Adam have been used in the UK more than 200 times, but they are strictly regulated.

The Nash family hope genetic screening will work for them

Further guidance on use of PGD is to be issued next year, following a public consultation exercise led by the regulatory body, the Human Fertilisation and Embryology Authority.

Head of ethics and policy at the British Medical Association, Dr Vivienne Nathanson said it was vital to ensure that embryos are only selected for "the right reasons"

"We could not possibly approve the procedure if the child concerned was going to be put through any pain and distress.

"Stem cell harvesting is harmless but if there was a need to carry out a bone marrow transplant that is not without risk and is an extremely uncomfortable procedure - where do you draw the line?"

Dr Paul Vey, consultant in stem cell transplants at Great Ormond Street Hospital in London said: "It raises questions about where the cut off line should be in genetic screening. It is a start towards being able to choose the right coloured eyes and the right intelligence."

The view was echoed by Jeffrey Kahn, director of the University of Minnesota's centre for bioethics, who said "It's quickly becoming like buying a new car, where you decide which package of accessories you want.

"I suspect it's only because we don't yet have the tests that we're not having parents asking for embryos without a predisposition to haemophilia or for kids who will grow to more than six foot tall."

Accusation of eugenics

Pro-life organisation, Life, sees the application of PGD to produce a "designer baby" as eugenics.

Dr Vey says the case raises questions

"This baby was brought into the world to do a job. In essence it is about people being killed to get the child you want. This is what our parents and grandparents fought against 60 years ago," said Life spokesman, Kevin Male.

Eugenics was also an accusation made by editor of Gen Ethics News, David King, who said the Nash family had simply "created a child to order".

"We are getting into a designer babies era, what I would call a eugenics area...to picking and choosing our children," he said.

And Dr Michael Jarmulowicz, Master of the Guild of Catholic Doctors said: "All children should be born for their own sake, not as a purpose for someone else's benefit."

'Waiting a long time'

But David Westmoreland, whose son Craig died from Fanconi anaemia, said parents of children with life-threatening disease had been waiting a long time for such developments.

"You should understand the hope that it gives to the families - of having a controlled way of getting a sibling donor," he added.

This provides a way for parents to have healthy children

Charles Strom, Illinois Masonic Medical Center,

Charles Strom, director of medical genetics at the Illinois Masonic Medical Center, where the Nash screening was carried out argued there is now potential for PGD to be used for thousands of children world-wide who require bone marrow transplantation for either genetic reasons or reasons of malignancy.

"This provides a way for parents to have healthy children and - without any risk to the child - use the child to save the life of a child that is already born." he said.