Cloned baby cancer warning

The first cloned baby could be born in November

Women who choose to have cloned babies run a high risk of developing a type of rare invasive womb cancer, scientists suggest.

The warning follows reports earlier this week that a patient of the controversial Italian fertility expert Severino Antinori is pregnant with a clone and due to give birth in November.

While most concerns raised over cloning have centred around the offspring, experts are predicting serious consequences for the mother.

If someone is prepared to take the risk of having a cloned baby, they may be willing to take the other risks associated with it

Dr Rosemary Fisher, genticist

Professor Richard Gardner, an expert on early mammalian embryo development, says the mother could be at risk of choriocarcinoma, an unusual form of cancer, unique to humans.

The cancer develops from the trophoblast, the part of an embryo that invades the womb wall and develops into the placenta.

Though the causes are unknown, poorly regulated genes controlling the growth of the placenta seem to be the key.

Animal experiments have shown these genes remain switched on in cloned embryos when they should be silenced by a chemical masking process called "imprinting"

Professor Gardner, a zoologist at the University of Oxford, fears this could trigger important genes - linked to the development of the placenta - to go into overdrive, accelerating its growth and posing high risks to mothers.

'Theoretical' risk

Professor Gardner, who chaired the Royal Society's working group on cloning, said: "The human has the most invasive placenta to start with.

"If placental growth goes awry, there's a greater propensity for this problem to emerge in humans than in other animals.

In an article in New Scientist, he admits that while the risk is only theoretical, people have paid far too little attention to it.

It is a theory expanded by geneticist Dr Rosemary Fisher, a senior fellow at Imperial College School of Medicine at London's Charing Cross Hospital.

She said: "It has been shown in certain conceptions, that where genes are abnormally expressed, they have a predisposition for the mother to develop choriocarcinoma.

"A cloned embryo may also have abnormal expression of genes and consequently increase the risk of choriocarcinoma for the mother."

However, she stressed that it is one of the most curable forms of cancer if detected at an early stage and even though there could be a hypothetically increased risk of developing cancer, some women may think it is a price worth paying.

She said: "If someone is prepared to take the risk of having a cloned baby, they may be willing to take the other risks associated with it."