IT’S one of the most amazing spectacles in reproductive technology—the
almost daily shifting of the moral and technical goalposts. Such is the power of
the swift transition, in the West at least, from simply “wanting” children to
having the “right” to bear them.
IVF is now commonplace. Routine egg freezing—and more pregnancies
deferred till middle age—will happen sooner rather than later. Gay men
becoming dads by using surrogates is already last year’s outrage, while mothers
in their sixties are increasingly tolerated. Even ovaries grafted to unusual
places could end up providing genuine ovulation. Are there any technical, or
even ethical, limits? It’s hard to be sure, at least if major scientific
conferences are anything to go by. Nor is the public showing any signs of losing
its appetite for assisted reproductive technology (ART).
The truth is that while there may once have been no evolutionary need for us
to be fertile beyond our twenties, today, careers and 80-year lifespans mean
there is no rush to get the next generation out. And, arguably, children may be
better off being born to mature, established 40 to 50-year-olds than to
teenagers.
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So while the moral qualms and panics are still real enough, pragmatism is
prevailing. And for now that means improving the success rate of IVF and ICSI,
which delivers the sperm directly into the egg. These techniques are nowhere
near good enough yet—a topic on everyone’s lips at the annual conference
of the American Society for Reproductive Medicine held in San Diego recently. A
round of IVF costs about $10,000 and has a 1 in 4 chance of succeeding on
average in women under 35—decreasing rapidly to 1 in 10 at 41.
That’s where embryo screening comes in. If a couple in their forties use IVF
to have a baby, they can have the embryos screened for chromosomal abnormalities
before they are transferred to the uterus, thus increasing their chances of
success. But now that pre-implantation genetic diagnosis (PGD) has been
around—and refined—over about a decade, the number of tests that can
be performed is about to shoot up. Dozens of disease-linked genetic mutations
can be spotted by examining a single cell from an embryo, and not all of these
mutations are for childhood diseases.
In theory, PGD could screen out any version of any gene the parents find
undesirable. And while the spectre of designer babies shows no signs of going
away, the scientists developing these technologies have their hands full helping
the people who need it—women with cervical cancer, men who carry a disease
gene, couples who can’t conceive naturally. Worldwide, only 50 clinics offer PGD
to women but the number is growing.
PGD involves removing one or two cells from an eight-celled embryo for
genetic analysis. Right now, PGD is used to detect major problems with
chromosomes—whether there is an extra number 21, for instance, denoting
Down’s, or whether some are missing. The purpose is to reduce the failure rate
of IVF so fewer embryos need to be transferred and fewer multiple pregnancies
result. Carrying three or more fetuses can lead to complications, and parents of
triplets have higher than average rates of depression and divorce.
A new method of examining all 23 pairs of chromosomes was reported at the
conference. The resulting headlines made some people nervous that a new eugenics
was upon us. In fact, the method still only spots big problems that prevent the
embryo from implanting in the first place. Nor is it quite ready for the clinic
because the screening takes longer than the maximum allowable time between
sampling the embryos and transferring them to the uterus.
Somewhat more ambivalent news came from one group at the meeting, which
reported a technique for spotting embryos with a mutation in the breast cancer
gene BRCA1. The only known effect of this mutation is to raise the likelihood
from 5 per cent to more than 50 per cent that the girl will get breast cancer as
an adult. The technique is still experimental, but the obvious question is
whether eliminating embryos that may or may not develop breast cancer really is
the best way to get rid of the inherited form of the disease.
Such concerns about selective breeding were raised just before the
conference, fuelled by the well-publicised news from New York that doctors had
chosen an embryo because it could provide a transplant of cord blood cells for
its sick 6-year-old sister.
The parents carry a rare disease called Fanconi anaemia from which their
young daughter, Molly, was dying. The chosen embryo was both free of the disease
and a compatible donor. Adam was born a healthy baby, and doctors successfully
transferred the cells to Molly.
Yet scratch this particular example and there’s little there. Parents can
already have a second child who they hope will be a compatible donor for the
sick one. It is up to them and their counsellors to make sure the new child
would be a loved member of the family, not just a source of spare parts. PGD
just means getting a compatible donor the first time, and in the case of Molly’s
brother, a healthy child.
So how does PGD really score in the ethical nightmare stakes? Right now, not
very high. We are far from screening embryos for stature and intelligence. For
one thing, these are multiple gene traits heavily influenced by environmental
factors. The chance of ever being able to create complex intelligence or
desirable personality traits from gene manipulation is slim. For another, even
if you could it would not be easy, or cheap. One of the most obvious
abuses—Chinese-style gender selection on purely cultural or political
grounds—has already been condemned by the ASRM in a statement issued last
year.
It’s anyone’s guess what will happen in the next five years, however, with
the advent of DNA chips and multi-gene screening. But as long as researchers are
unpicking such apparent certainties of human reproduction as the “safe period”
for women—next to impossible to predict, it turns out—then the PGD
goalposts are likely to stay more or less where they are now for a while
yet.