By BBC
News Online science editor Dr David Whitehouse
 | | Mitochondria
contain genes outside the cell's nucleus |
Scientists
have confirmed that the first genetically altered humans have been born and are
healthy.
Up to 30 such children have been born, 15 of them as a result
of one experimental programme at a US laboratory.
 | | An
"unwelcome" development say scientists |
But
the technique has been criticised as unethical by some scientists and would be
illegal in many countries, including the United Kingdom.
Genetic fingerprint
tests on two one-year-old children confirm that they contain a small quantity
of additional genes not inherited from either parent.
The additional genes
were taken from a healthy donor and used to overcome their mother's infertility
problems.
Germline modification
The additional genes that
the children carry have altered their 'germline', or their collection of genes
that they will pass on to their offspring.
Altering the germline is something
that the vast majority of scientists deem unethical given the limitations of our
knowledge.
It is illegal to do so in many countries and the US Government
will not provide funds for any experiment that intentionally or unintentionally
alters inherited genes.
There is no evidence that this technique is worth
doing
Lord Winston The children were born following a technique called
ooplasmic transfer. This involves taking some of the contents of the donor cell
and injecting it into the egg cell of a woman with infertility problems.
The
researchers, at the Institute for Reproductive Medicine and Science of St Barnabas
in New Jersey, US, believed that some women were infertile because of defects
in their mitochondria.
These are tiny structures containing genes that
float around inside the cell away from the cell's nucleus, where the vast majority
of the genes reside. There can be as many as 100,000 of them floating in the cells
cytoplasm.
Two mothers
They are essential to cellular energy
production and scientists suspect they have many other important but as yet unappreciated
roles.
Mitochondrial DNA is passed down from generation to generation
along the maternal line.
The US researchers wanted to supplement a woman's
defective mitochondria with healthy ones from a donor.
Having just tested
the children born as a result of this procedure, the scientists have confirmed
that the children's cells contain mitochondria, and hence genes, from two women
as well as their fathers.
Writing in the journal Human Reproduction, the
researchers say that this "is the first case of human germline genetic modification
resulting in normal healthy children".
'Great reservations'
British
experts have severely criticised the development.
Infertility pioneer
Lord Winston of the Hammersmith Hospital in London told BBC News Online that he
had great reservations about it.
"Regarding the treatment of the infertile,
there is no evidence that this technique is worth doing," he said. "I am very
surprised that it was even carried out at this stage. It would certainly not be
allowed in Britain.
"There is no evidence that this is a possible valuable
treatment for infertility," he added.
Lord Winston said that, although
the number of additional genes involved was tiny, it was in principle the wrong
thing to do.
The Human Fertilisation and Embryology Authority (HFEA),
the body that monitors and regulates UK reproductive medical activities, told
BBC News Online that it was aware of the technique but had decided not to allow
it in the UK because of its uncertainties and the possible alteration of the human
germline.
'Back door'
The HFEA said it was an unwelcome
development that "adds additional concern" to their worries. US researchers have
also criticised the production of genetically altered children.
Eric Juengst,
of Case Western Reserve University, said: "It should trouble those committed to
transparent public conversation about the prospect of using 'reprogenetic' technologies
to shape future children."
The US Government Recombinant DNA Advisory
Committee told BBC News Online that the researchers had carried out this work
without government money.
The committee said that in no circumstances
would it consider any request for government funds that would result in modification
of the human germline.
Professor Joe Cummins, of the University of Western
Ontario in Canada, told BBC News Online: "Now is not the time to bring in human
germline gene therapy through the back door." |
