Scientists funded by Cancer Research UK are issuing a warning on the potential dangers of cloning following their discovery that a rare childhood illness is four times as common in babies born after IVF treatments.
The condition, called Beckwith-Wiedemann syndrome, predisposes children to birth defects and cancer, and is linked with a genetic phenomenon known as imprinting. This means that certain genes act differently depending on whether they are inherited from the mother or the father.
The researchers believe that IVF increases the risk of the syndrome because it interferes with imprinting. Cloning, which is a more radical technique than IVF, is known to destroy normal imprinting and could dramatically increase the risk of conditions like Beckwith-Wiedemann syndrome.
Beckwith-Wiedemann syndrome normally affects between two and five children in every 100,000. Children who are born with the condition are more likely to suffer from birth defects and a number of children’s cancers; primarily Wilm’s tumour, a cancer of the kidney.
The researchers looked at a group of 149 children suffering from Beckwith-Wiedemann syndrome and found that four per cent were born either after in vitro fertilisation or a related technique called intracytoplasmic sperm injection. Normally these techniques only account for about one per cent of children born. From these results the researchers calculated that children born from assisted reproduction were at significantly increased risk of Beckwith-Wiedemann syndrome.
Scientists believe that the condition is caused by disruption to the imprinting of a particular gene. Imprinting means that a gene ‘remembers’ whether it came originally from the mother’s egg of the father’s sperm.
Most genes are not subject to imprinting but the ones that are tend to be involved in the development of the baby when it is still growing in the womb. Imprinted genes that are inherited from the father tend to encourage the baby to grow bigger while the equivalent genes from the mother tend to keep growth in check.
The research is a collaboration between scientists at the University of Birmingham, led by Professor Eamonn Maher and Dr Wolf Reik at the Babraham Institute in Cambridge.
Dr Reik explains: “The genes themselves are not necessarily any different but imprinting controls how active the gene is. If the imprinting goes wrong, control is lost and this can result in unregulated growth.
“Imprinting is set when the sperm or egg is produced and we believe that IVF and ICSI interferes with the process just after fertilisation, increasing the risk that a child will develop Beckwith-Wiedemann syndrome.”
He adds: “Evidence is emerging that imprinting is also faulty in cloned animals so it¹s not unreasonable to think that human cloning would put children at risk of this condition and others like it.”
Sir Paul Nurse, Cancer Research UK’s Chief Executive, says: “Cancer Research UK is opposed to reproductive cloning and this research highlights just one of the severe problems that may result.”
Journal of Medical Genetics40 (1)
The research confirms that the national population of offspring conceived using IVF or ICSI should be followed up to evaluate their long term health.
Imprinting works by adding small molecules to the cell’s DNA, a process called methylation, which usually prevents the genes from working.
Intracytoplasmic sperm injection is used to combat male infertility. Sperm are removed from the tesicle and injected directly into an egg by scientists in a lab. The fertilised egg is then implanted into the mother’s womb.
Approximately five to ten per cent of children with Beckwith-Wiedemann’s Syndrome develop cancer.