06 March 2017
ByAppeared in BioNews 891
Naked Genetics podcast
Presented by Dr Kat Arney
It's amazing how a string of four little chemicals can be so controversial. More and more, we hear about the genetics behind everything from education and intelligence to appearances and sexuality, not to mention diseases and our ancestry. This can be a murky and politically charged area, not least because of the so-called alt-right's burgeoning interest in genetics.
Dr Kat Arney's fascinating and wide-ranging Naked Genetics podcast eased us into genetic testing with the less controversial topic of cancer.
Her first guest was Professor Nazneen Rahman, a geneticist at the Institute of Cancer Research who can also belt out a jazz number. She studies how your genome can affect your risk of developing various cancers, particularly ovarian and breast.
Any discussion of risk is liable to make many people feel scared, overwhelmed and bored, all at the same time. It's frankly unnatural to wrap your head around these probabilities – just think about how you react whenever the weather forecast turns out wrong – and it takes a lot of training to get the human brain to think probabilistically.
Beyond a handful of statistics, Professor Rahman avoided numbers in favour of a clear and articulate explanation of the role of genetic testing in cancer. In the UK, we start with people already diagnosed with cancer, then reach out to family members who might also be at risk. Professor Rahman discussed how this approach means that cancer patients can also be given more personalised information about their disease.
Screening the entire population for particular mutations, she explained, is ineffective because of their rarity. Around this point, I felt that they should have mentioned the inherent pros and cons of screening. All tests are inaccurate in two ways: there's a chance the test will say you're sick when you aren't (a false positive) or it will say you're well when you're sick (false negative). Both outcomes are harmful and unavoidable, and this must be taken into account when rolling out any kind of screening programme.
Next up was Dr Tony Gordon, who spoke at the Progress Educational Trust's 'Testing, Testing, 1, 2, 3' debate about pre-implantation genetic screening (PGS) and pre-implantation genetic diagnosis (PGD) in September (see BioNews 870). He's the UK laboratory director of Genesis Genetics, which tests for genetic disorders in embryos produced through IVF as well as in fetuses.
Dr Gordon said his company can test embryos from as little as five days after fertilisation (during IVF) by taking cells from the part that will grow into the placenta. This PGS test makes sure embryos have the correct number of chromosomes. PGD, on the other hand, zooms in to look at genes and, by Dr Gordon's count, can test for around 240 heritable conditions.
Inevitably, genetics tends to make things more complicated, not less, in all respects. As Dr Arney said: 'It's not quite as simple as one gene, one fault, one disease.'
Luckily, the odds are against this kind of embryonic testing leading towards a perfect and perfectly homogenous master race, because – as Dr Gordon points out – if you screened for more than one or two conditions, you'd quickly run out of embryos to transfer during IVF.
He also brought up an interesting point when talking about how, with late-onset disorders like Huntington's, they must tread carefully when talking to parents who might not be aware that they have the gene themselves.
The third and final guest was Mike McNamee, professor of sports science at Swansea University, who specialises in ethics. Professor McNamee critiqued the shaky science behind the newest batch of direct-to-consumer genetic testing kits. These kits claim to uncover potential sporting or artistic ability – essentially promising to quantify whether a child would feel more at ease in front of an easel or a pommel horse.
Professor McNamee highlighted a gene called ACTN3 that has been linked to power and speed in athletes, but only to a point as a famous long-jumper does not express this gene. As he rightly mentioned, 'being a world class sprinter requires a million other things', not least 'the motivation, dedication, the commitment' to do it in the first place. (I may be expressing heroic quantities of ACTN3 right now, but the only time you'll see me sprint is when they call last orders at the bar.)
He went on to say that it's 'preposterous' and 'fallacious' to reduce any kind of complicated, specialised activity requiring a mixture of talent, training and luck to a string of DNA. There are always all manner of social, historical and environmental contingencies that influence what we want from our children as well as what they might want for themselves.
This half-hour programme was packed with lots of other interesting titbits that Kat Arney and her guests talked about. I highly recommend giving this podcast your time.