|
|
|
SCIENCE UPDATE
Cancer case raises gene therapy fears
A second case of leukaemia among children given a revolutionary form of gene therapy has increased concerns about the treatment.
The patient, from France, was a boy “cured” of a condition called X-SCID, popularly known as “bubble boy disease”. This genetic defect leaves children without an immune system — they need to be kept in sterile conditions or might catch fatal infections.
The treatment involves taking the faulty immune cells from the child’s bone marrow, genetically modifying them in the laboratory so they work properly, then putting them back to kick-start the immune system.
Four children have received similar pioneering treatment in the UK. It appeared to work perfectly in many of the patients given the treatment.
However, another French boy who was treated at the Necker Hospital in Paris fell ill with a leukaemic illness late last year. Both boys are said to be responding to treatment and are “stable”, but the emergence of another case is a severe blow to the development of gene therapy.
The Food and Drugs Administration in the US, and the French authorities have now suspended the treatment, and many other trials involving a similar gene modification technique. In the UK, no further X-SCID gene therapy will be carried out until the question marks over safety have been resolved.
Dr Harry Malech, of the National Institute of Allergies and Infectious Diseases in the US, says: “I think we shouldn’t view this as the death knell to gene therapy. . . . We need more good science to work out what went wrong.”
IVF offers cloning warning
IVF babies are more likely to suffer from a rare gene disorder and scientists say the finding is another good reason not to make human clones.
Beckwith-Wiedemann syndrome is a rare condition which causes too much growth, kidney abnormalities and a raised chance of tumours.
The syndrome is the result of errors in a process called “imprinting” — which happens when the DNA from mother and father are combined when the embryo is first conceived.
Every embryo is a combination of two sets of genes — one from its mother and one from its father. However, certain genes perform differently, and are more or less active, depending on whether they come from the father or the mother.
This “imprinting” is a key control which makes sure the foetus develops correctly while it is in the womb.
Scientists believe that fertility techniques such as IVF and ICSI — in which a single sperm is injected into an egg — may be disrupting this imprinting process.
Although in the vast majority of cases the baby would be healthy, in some cases the problem would have an effect on their future health.
The researchers from the Universities of Birmingham and Cambridge looked at 149 babies diagnosed with the syndrome.
They found that six out of the 149 had been conceived via IVF or ICSI, or 4 per cent.
The proportion of babies born using IVF in the UK is only 1 per cent, meaning that IVF babies are more likely to fall prey to the disorder than those conceived naturally.
Dr Wolf Reik, from the Babraham Institute at the University of Cambridge, said: “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 interfere with the process just after fertilisation, increasing the risk that a child will develop Beckwith-Wieemann syndrome.”
Clone damage: However, he said that the result was bad news for supporters of human reproductive cloning. There is significant evidence that cloning techniques also interfere with imprinting. In animal experiments, many foetuses spontaneously miscarry at various stages of pregnancy, and scientists are still not sure why, although miscarriage is often a safety mechanism that halts a foetus which is not developing correctly.
Dr Reik said: “Evidence is emerging that imprinting is also faulty in cloned animals so it’s not unreasonable to think that human cloning would put children at risk of this condition and others like it.”
‘Reading circuit’ in brain by age 7
The networks the brain relies on to read may be in place earlier than expected in children, new study findings suggest.
Using a scan called functional magnetic resonance imaging (fMRI) to measure brain activity in children ages 5-7, researchers found that reading-related brain networks were in place by age 7.
In an interview, the lead investigator, Dr William D. Gaillard, explained that the left side of the brain is the dominant one for language skills in 95 per cent of people. Gaillard and his colleagues expected that this predominance of the left brain for reading tasks would already be apparent in children ages 5 to 7.
The study, which included 16 healthy children, bore out those expectations. Even though the researchers thought that reading-related brain activity would be focused on the left side of the brain in these young readers, they expected that younger children would show more reading activity on both sides of the brain than a previously studied group of older kids.
That did not turn out to be the case, the researchers report in the Jan 14th issue of the journal Neurology. In most children, the same reading-related brain network found in adults was in place by age 7, according to the report. In some cases, these networks were comparable by age 5 to those seen in adults. — Dawn ScienceDotcom Report
|
|
|
|
