Time to think about gene therapy in womb- US experts
RTw 25.09.98 21:34
Copyright 1998 Reuters Ltd. All rights reserved.
The following news report may not be republished or redistributed, in whole or in part,
without the prior written consent of Reuters Ltd.
By Maggie Fox, Health and Science Correspondent
WASHINGTON, Sept 25 (Reuters) - Leading U.S. researchers in gene therapy say it is finally
time to think about trying the still-experimental technique in the womb.
While they are not asking permission to try the technique -- yet -- they asked advisers to
the National Institutes of Health (NIH) on Thursday and Friday to think about the
implications of such an experiment.
The idea would be to "fix" babies with genetic defects before they are born. But
there is a long list of safety and ethical considerations.
"This meeting was not designed to ask for approval, but the sense of the committee is
that the technology has advanced enough that this is an appropriate time to discuss this
in a public forum," said Dr. W. French Anderson, one of the pioneers of gene therapy,
who was speaking to the committee.
Anderson said he thinks his lab is only about two to three years away from being able to
do this.
His lab did the first-ever gene therapy experiments on a human in 1990, when it tried to
use the technique to treat children with ADA deficiency, a genetic defect that leaves them
with no immune system.
Such babies often become "bubble children," forced to live in a plastic bubble
to protect them from infection.
Anderson has tried injecting genes that control production of ADA into the children, in
the hope their bodies will take up the genes and start producing their own. He has had
mixed results and no outright cure.
To do any of this work, he has to get permission from the NIH and its DNA advisory
committee, which consists of scientists, lawyers and other experts.
Anderson said he believes that gene therapy might work better before a baby is born,
because its body is still forming and might absorb the new genes better.
One of the biggest risks is that the new gene would be absorbed not only by somatic cells
-- the cells that make up most of the body -- but by germ cells -- eggs and sperm.
If that happened, the new gene could be passed down from generation to generation.
"The level of inadvertent germline transmission should be extremely low but, how
low?" asked Anderson. He said the committee had asked him to come back with
information from animal tests that would indicate how often this might happen.
And that leads to an even stickier question -- could and should scientists do it on
purpose? "Does that by itself open up the potential for great harm by opening the
door for intentional germ line gene transfer when most of us believe we are at least 10 or
15 years away from technically being able to do it," Anderson asked.
The book is still open on whether regular gene therapy is safe. It is still only allowed
on the very sickest and most desperate patients.
"We need 10 to 15 years experience with somatic cell (gene therapy) to see if there
are no problems," Anderson said. "The clock has just started ticking. Most of
the gene therapy patients have been terminal cancer patients and they have died."
It is possible that gene therapy itself could cause cancer, Anderson says. "If every
patient who gets gene therapy develops leukaemia after 10 years, you clearly don't want to
do germline therapy," he said.
The retroviruses used to deliver genes into the body insert their gene loads randomly.
"If they happen to go into next to a cancer gene, it might turn on the oncogene, or
if it goes in next to a tumour suppressor gene it might knock down the defence of the
immune system," Anderson said.
Many groups oppose Anderson's proposed experiments.
The Council for Responsible Genetics issued a statement calling the the idea ominous and a
step toward the creation of "designer babies."
"If this first proposal is accepted how much longer will it be before ... any child
who doesn't measure up to some arbitrary standard of health, behaviour or physique is seen
as flawed?" it asked.