Male-only conception 'highly speculative'

Reproductive biologists have described as "far-fetched" the idea that cloning technology might be used to help homosexual couples conceive their own children.

The notion was floated by Dr Callum MacKellar, a biochemist in Edinburgh, UK, who edits a journal on bioethics.

He suggested nuclear transfer techniques pioneered in Dolly the sheep could eventually be used to create "male eggs" from one man that would be fertilised by the sperm of another.

But many commentators dismissed the proposition as speculative and well beyond what was currently possible in biology.

"To me there are important issues to focus on, but this is not one of them," said Professor Azim Surani of the Wellcome/CRC Institute of Cancer Research and Developmental Biology in Cambridge.

Female genes

Dr Callum MacKellar, who runs a non-profit organisation called European Bioethical Research, claimed scientific advances could, one day, result in a homosexual couple having a baby that combined the DNA of both fathers.

"It's theoretically possible - if they were able to control the imprinting - to have a child that's born as a result of having two fathers," he said.

A "male egg" would be created by removing the nucleus from a female's donor egg and replacing it with the nucleus from a sperm cell.

The new egg would then have male DNA and could be fertilised in-vitro by another sperm before being implanted in the womb of a surrogate mother.

But Professor Azim Surani said there were significant obstacles currently preventing the idea from becoming a reality.

Narrow timeframe

He said that normal development in mammals required both male and female genomes because they had complementary information.

"The studies we have done clearly show that there are some genes that are only active when they come from the mother," he said. "This is the phenomenon known as imprinting."

He said scientists were a long way from understanding how the mechanism worked.

"The genes have to go through the female germline. They acquire the ability to be switched on during the growth of the oocyte (an immature female reproductive cell) and there is a very narrow timeframe over which this can occur - there is no other time when this process can take place."

Dr MacKellar conceded that there were major biological impediments to male-only conception but said: "The whole question of biology since Dolly the sheep is absolutely fascinating and it's the big question at the moment."

Reproductive cloning

The UK Parliament is about to vote on a Bill which, if passed, would permit cloning techniques to be used for therapeutic purposes. This would include the production of replacement cells for the treatment of degenerative conditions such as Parkinson's and heart disease.

The legislative changes are based on recommendations produced by an expert panel led by England's Chief Medical Officer, Sir Liam Donaldson.

Under the proposals, male-only conception would not be permitted because it is likely to be regarded as reproductive cloning.

The cloning of farm animals has shown the technology to be extremely problematic and far too dangerous to be used to make a full-body copy of a human.

But Dr MacKellar claimed the Donaldson committee had not looked into the ethical issues raised by male-only conception.