DIY doctor: Do home DNA tests reveal the full truth?

DIY doctor: Do home DNA tests reveal the full truth?

Suzanne Harrington uses a home kit to see what risks her body could potentially be exposed to. Here, she shares the results.

When the world’s largest collaborative science project concluded in April 2003, scientists had, for the first time, accurately mapped the human genome.

Sixteen years later, I find myself spitting into a test tube at home, then popping it in a pre-addressed envelope and posting it to a laboratory for DNA analysis.

Not for any Jeremy Kyle-type reasons (I know who my parents are), and not because I am particularly curious about my ancestry (ditto); DNA testing has long been associated with identifying reluctant paternity, or being of interest to amateur genealogists — and confounding racists by revealing their DNA to contain material from other ethnic groups — as well as quirkier uses: When a neighbour’s German shepherd puppy grew to the size of a donkey, a home testing kit for pets showed Great Dane DNA.

No, I want to know, roughly, what conditions my body are predisposed to, so I can look out for them in the future. (Ancestrally, turns out I’m 100% European, with a dash of Neanderthal. No surprises there).

Kitted out

DIY doctor: Do home DNA tests reveal the full truth?

Direct-to-consumer DNA analysis kits have been gaining mainstream popularity as a preventative health measure since 2017; the more we know about our bodies, the better we can take care of them now, so that they last better in the future.

(A high-profile and extreme example of such preventative care was when Angelina Jolie discovered she was carrying the same breast cancer gene which killed her mother, and had a preventative double mastectomy).

While obviously not as exacting as tests done in a hospital, DNA kits can be useful indicators of future health issues, although it’s important to remember that home kits do not provide whole genome sequencing, but rely on genotyping — that is, looking for specific variants, rather than going through a person’s entire genetic information.

Around 12m Americans have had their DNA tested, mostly for reasons of ancestry curiosity. UK-based Atlas Biomed, which charges £149 (€172) per DNA analysis, has so far tested 15,000 people focusing on health, although ancestry is included.

In terms of privacy, the data belongs to you — if it is shared into a bigger database by the analysis company for medical research, you are not identified, other than as a male or female human.

So how does it work? DNA (deoxyribonucleic acid) is made up of repeating units called nucleotides, each containing a sugar and a phosphate molecule, which makes up the main structure.

It comprises four organic bases, A (adenine), G (guanine), C (cytosine), and T (thymine).

It’s the specific order of A, G, C, and T within a DNA molecule which is unique to every individual – what makes ‘us’ us.

Reading the alphabet

DIY doctor: Do home DNA tests reveal the full truth?

Erin Carney is a genetic counsellor with Atlas Biomed, the lab which analysed the DNA in my saliva, then sent me its findings electronically after about six weeks.

She talks me through what she terms the psychosocial aspects of my results.

Turns out I’m at high risk of coronary heart disease, Alzheimer’s, and osteoporosis. Yikes.

“The body reads the four-letter alphabet of DNA — A, C, T, G — like a novel,” says Carney.

“There are 3bn letters of DNA code. And while 99.9% of DNA is the same in everyone, 0.1% is coded differently.

"It is this 0.1% variant which can cause disease. We call this pathogenic variant.

“Atlas Biomed screens for several hundred diseases — we are not screening all 3bn but to see if, for example, people are carriers of cystic fibrosis.

"Also, there are thousands of known variants for breast cancer, but Atlas screen for several hundred.

"We all have two copies of DNA, one from each parent, but just one set needs to be off in order to be at risk of developing disease.”

Risky results

DIY doctor: Do home DNA tests reveal the full truth?

Closer inspection of my results are not as grim as they sound. It starts with a baseline of the average risk of developing heart disease (4%) and then shows how my risk is 6.32%.

The other 2.32% risk comes from genetics (1.12%) and factors relating to information I provided — having had depression adds another 1.20% risk.

“It’s at the higher end of those who have taken the test,” says Carney.

“But these results don’t take everything into account. They are not gospel.”

Worse is my Alzheimer’s risk: 9.99%. Just by being female, the average baseline risk is 7.70%, and although my genetic makeup reduces this risk by 0.79%, my former depression ups it by 3.08%.

And worse again is my chances of developing osteoporosis — as a woman, there is an average 15.40% risk of development, and despite my genetic protection against it (0.08%), “other factors” — being an ex smoker — have bumped it up 1.94%.

It’s not all bad news, however. When we used to believe that everything was genetic, these days we know it’s 80% lifestyle, 20% DNA.

Healthy fresh food, exercise, taking good care of mental health, practising yoga to strengthen bone density, reduce stress, and lower blood pressure — these are all things that can be done now rather than being floored later by a genetic predisposition.

“The best thing to do is to share these results with your GP, to see if there is anything that can be done now,” says Carney, reiterating the importance of not taking commercial DNA testing as a medical diagnostic.

“You still need a mammogram.”

DIY doctor: Do home DNA tests reveal the full truth?

In other words, do not rely on these tests.

Exeter University recently conducted tests into a commercial DNA chip and found it was accurate only 17% of the time when detecting a rare breast cancer gene mutation; there is concern that people could be falsely reassured by negative results.

Conversely, doctors in Britain called for direct-to-consumer kits to be more tightly regulated, citing an increase in individuals trying to schedule surgery based on flawed results.

Do the test but use it as a guide and awareness-raising tool towards healthier living. For medical diagnostics, you need to undergo tests at a hospital.

Also, doing a microbiome test (where you send not saliva but a small sample of poo through the post) can give a snapshot of your current health, which can also be useful.

Although, again, not gospel.

Before you order a DNA home test

PROS

  •  Promotes awareness of genetic diseases

  •  Nudges you to greater health proactivity

  •  Bypasses medical appointments

  •  Affordable and non-invasive

  •  Your data is added to a larger database which can be used anonymously in medical research

    CONS

  •  Tests only for some conditions and diseases

  •  Is only a guide, not a medical diagnostic

  •  There have been cases of individuals reacting in alarm to results and scheduling unnecessary medical interventions

  •  DNA testing companies are largely unregulated

  •  Tests can be misleading or oversimplistic

  •  Promotes awareness of genetic diseases

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