The world?s first cloned baby could be born in November, according to Italian fertility expert Severino Antinori. Most animal clones have short, unhealthy lives. But even if the baby is healthy, the mother could be at high risk for a rare invasive womb cancer.
Richard Gardner, who chaired the U.K. Royal Society?s working group on cloning, says the mother could be at risk from 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 involved.
Animal experiments have shown that these genes remain switched on in cloned embryos when they should be silenced by a chemical masking process called ?imprinting.? This means important genes linked to the development of the placenta could go into overdrive, accelerating its growth and posing high risks to mothers.
?The human has the most invasive placenta to start with,? says Gardner. ?If placental growth goes awry, there?s a greater propensity for this problem to emerge in humans than in other animals.? Scientists have paid little attention to this problem, focusing instead on the fate of the clone itself.
Barry Hancock, of Weston Park Hospital in Sheffield, which specializes in the treatment of trophoblastic cancers, agrees that abnormal imprinting in the genes of cloned human embryos may increase a mother?s risk of the disease. ?But it?s a theoretical risk,? he says.
Harry Griffin, of the Roslin Institute near Edinburgh where Dolly the sheep was cloned, says, ?It?s very difficult to know what, if anything, is true.? See news story ?Woman Pregnant With Clone?, click here.
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