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'BRCA1-free' birth isn't a "slippery slope to designer babies"

Posted Apr 09 2009 7:17pm
Does the birth of a baby lacking a cancer-causing gene mean we're on a slippery slope to designer children?

Does the birth of a baby lacking a cancer-causing gene mean we're on a slippery slope to designer children?

January 2009 began with the birth of a baby girl at a London hospital. Her parents had undergone a form of in vitro fertilisation (IVF), which meant that, unlike the father’s family, the baby was free of a breast cancer-causing mutation that had plagued the women of his family for generations.

This is exciting news.

Every woman across three generations of the father’s family had previously been diagnosed with aggressive breast cancer, many in their 20s. Tests had shown that the family carried a faulty copy of the BRCA1 ‘high-risk’ breast cancer gene.

Although BRCA1 mutations are rare in the population as a whole, between five and eight out of ten carriers of this gene fault will go on to develop breast cancer, often at a young age (compared to an overall risk of one-in-nine of the general population ). And, as is often the case with early-onset breast cancer, BRCA1 tumours will often be extremely aggressive.

So the couple took the decision to use the latest technology to ensure that their baby didn’t carry the BRCA1 fault - a mutation that the couple described as ‘like having the Sword of Damocles hanging over the family’. And, thanks to the help of the private Assisted Conception Unit at London’s UCL Hospital, they gave birth to a healthy, BRCA1-mutation-free baby on January 9 th.

As with all advances in reproductive technology, this caused controversy in the media and the inevitable invocation of the ‘designer baby’ cliché - a loaded phrase that simultaneously draws on imagery of over-accessorised parents and Frankenstein-esque forbidden knowledge.

But is it really a ’slippery slope’ from here to choosing hair or eye colour, or even intelligence, as critics claim? Or is this an exciting advance for a small minority of people who live in the shadow of an inherited risk of disease?

 

During IVF, an egg cell is injected with sperm outside the womb

During IVF, an egg cell is injected with sperm outside the womb

How did they make a BRCA1-mutation-free embryo?

The procedure the couple underwent is known as pre-implantation genetic diagnosis, or PGD. It’s an extension of the IVF process, through which couples conceive if they’re having trouble going the ‘natural route’.

‘Normal’ IVF involves the creation of multiple embryos, only a few of which are implanted into the mother’s womb.

But PGD contains an additional genetic test, carried out on the embryos created before they are implanted into the womb.

The family in this story created eleven embryos via IVF. Of these, five were shown to be free of the BRCA1 mutation. Two of these were then implanted into the mother’s womb, where one grew into a healthy baby.

The other mutation-free embryos were frozen, in case the couple wanted to have more children in future.

Why is this controversial?

PGD is not new. It’s been used for many years to help couples have children free of inherited diseases, such as cystic fibrosis or Duchenne muscular dystrophy, that have affected their parents’ families.

These diseases are caused by the inheritance of specific genetic defects. Children born with these defects generally have a 100 per cent chance of developing the disease. And for many of the conditions, there is no cure.

What’s different in the case of the so-called ‘BRCA baby’ is that children carrying a faulty copy of BRCA1 aren’t absolutely certain to get breast cancer - they have a fifty to eighty per cent chance - and breast cancer is a disease that can be treated, often successfully.

Nor, as several critics have pointed out, is a child born with a ‘normal’ copy of the BRCA1 gene guaranteed to be ‘cancer-free’. This is different from a child born with two normal copies of the CFTR gene, who will be pretty much certain not to develop cystic fibrosis.

A child without  BRCA1 gene fault still has a roughly one in three chance of getting some form of cancer at some point in their lives - just like the rest of us.

But instead of having a 50 to 80 per cent chance of developing breast cancer - probably at a young age - they are now on a par, genetically speaking, with the general population.

These facts have lead certain groups to criticise the procedure, and to speculate that this is the ‘thin end of a wedge’.

As a spokesperson for the charity Life said,

“The big question is: Where is this going to stop? We need to remember that we are more than the sum of our genes.”

These criticisms are understandable.

But as a charity concerned with understanding and beating cancer, we think the advent of PGD for ‘high risk’ cancer genes is extremely good news. As a result, many families who have been affected for generations by the spectre of familial cancers now have a chance to spare future generations this fate. And we have several points to make about the criticisms of this process.

“Not ‘cancer-free’”

Although, as several reports pointed out, the baby isn’t guaranteed not to get cancer (if you’ll excuse the double negative), its chances of having early-onset, aggressive breast cancer are hugely reduced in the absence of a faulty BRCA gene. The process has, in effect, levelled the playing field in terms of cancer risk. And there’s nothing wrong with that, in our opinion.

“Breast cancer can be treated”

Treatment is indeed available for breast cancer, and survival rates have been increasing as treatments get better. But despite these advances it can still be a harrowing, debilitating process - and success is not guaranteed. On top of this, the prognosis hasn’t been increasing at the same rate for all types of breast cancer - and early-onset, aggressive disease has, in general, a poorer outlook.

And having IVF isn’t easy. Undergoing an invasive and lengthy procedure - with no guarantee of success - to spare future generations the spectre of inherited breast cancer, and the treatment that comes with it, is not a decision to take lightly

“It’s a slippery slope to designer babies”

Aside from the slippery slope being a well-recognised logical fallacy, there are several reasons why this won’t lead to parents successfully selecting favourable ‘designer’ characteristics any time soon.

For a start, like cystic fibrosis and other genetic diseases, BRCA1-driven breast cancers are linked to a single, detectable genetic fault. But things like height, weight, and intelligence are influenced by much more subtle genetic variations (rather than faults per se ) - variations that we don’t really understand.

Even in the case of the subtle variants linked to cancer (such as those being marketed in genetic tests for the disease ), we still don’t know enough about them, and how they interact with other genetic variations, or with our environment.

And just as we have thousands of gene variations that help make us the unique human beings we are, the interaction of these variations determines our overall cancer risk.

So it’s hard to see how PGD techniques to weed out these variants, as we currently understand them, could get approval from the Human Fertility and Embryology Authority (HFEA) - the body who give licenses to clinics wishing to carry out such procedures.

HFEA said in a statement in 2006, when licensing the procedure for use in inherited cancer susceptibility:

“The inherited conditions suitable for PGD testing are very uncommon. This is not about opening the door to wholesale genetic testing. This is about considering a particular group of genetic conditions to be sufficiently serious to merit the use of PGD embryo testing.

“These genetic tests can still only be used for a minority of people if there is a clear history of cancer across generations of a family”.

At Cancer Research UK we support the right of a couple to choose to undergo this procedure. We accept that there are people and groups who will never accept that this sort of technology will be a good thing, and we respect these views. But our concern is with helping people affected by cancer.

Preimplantation genetic diagnosis offers hope to families who have been affected by the disease for generations.

The future

Scientific research has identified - and will continue to identify - the genes linked to cancer. But only a minority of these are ‘high-risk’ genes - genes that, when they go wrong, lead to cancer the majority of the time.

We’ve probably already identified the majority of these genes. As well as the BRCA genes (which Cancer Research UK was involved with discovering and linking to cancer ), other gene faults cause conditions like Familial Adenomatous Polyposis, Hereditary Non-polyposis Cancer Syndrome, and Li-Fraumeni syndrome.

So it’s highly likely that PGD will be used by families in the future to remove these genetic nasties from their lineage. And this could lead to more headlines and commentary about ‘playing God’ and ‘designer babies’.

This is not a black and white area. How we apply science to the society we live in, and how this affects future generations, has always been a controversial area and will continue to be so - and debate and discussion about how we shape our future is essential.

But as an organisation dedicated to beating cancer, we think that science that can help families avoid inherited cancers is science that should be grasped with both hands..

Henry

This entry was posted on Friday, January 30th, 2009 at 3:27 pm and is filed under Breast, Cancer in the news, Genes. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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