What you should know about DNA testing for disease risk

Population DNA testing for disease risk is coming. Here are five things to know.

What you should know about DNA testing for disease risk

Population DNA testing for disease risk is coming. Here are five things to know

Screening millions of healthy people for their risk of disease can be cost-effective. But it raises ethical and regulatory concerns. from www.shutterstock.com Paul Lacaze, Monash University and Jane Tiller, Monash University

DNA testing to predict disease risk has the potential to prevent disease and save lives. Yet few Australians can currently access predictive DNA testing via the healthcare system.

That may soon change.

As technology improves, the cost of DNA testing declines, and the Australian Government invests in genomics, universal DNA screening is becoming feasible.

DNA screening would involve large numbers of otherwise healthy people having DNA testing, by providing a simple blood or saliva sample, to identify risk of certain conditions. This includes types of cancer or heart disease that run in families – and can be prevented.

Being identified at increased risk doesn’t mean you’ll get the disease. But identifying risk early and before symptoms appear provides the opportunity for prevention. Prevention can be achieved through regular check-ups, medications or even risk-reducing surgeries.

The new opportunities for prevention genomics offers could transform public health.

Read more: Why we should test everyone's genes to predict disease

But a number of challenges exist. How would we provide DNA testing to millions of people and deliver the required health services to all those at high risk?

What about genetic discrimination? Could testing cause more harm than good, and lead to over-diagnosis? How would the health-care system fund this level of testing, and would it be cost-effective? Do people even want testing?

The concept of population DNA screening is daunting. But the benefits could be huge.

Australia has the chance to do it properly. Here are five things to know.

1. DNA screening is not a crystal ball, but it identifies risk

DNA testing can’t tell us everything. It estimates risk well for certain types of diseases, mostly those caused by single gene changes. These are distinct from other common diseases where genetic risk accumulates from hundreds of genes and is harder to predict.

Potential candidates for screening include cancers such as breast and ovarian cancer caused by the BRCA genes, colorectal and other cancers caused by Lynch syndrome, inherited high cholesterol and other types of genetic heart disease.

Although each of these conditions alone are relatively rare, together they put an estimated one in 38 adults at high risk.

Read more: Should doctors share gene tests after a death in the family?

Genetic risk for these conditions is often identified too late, after cancer is diagnosed or someone dies from a cardiac arrest. Limited health budgets mean testing is usually offered only to people diagnosed with genetic diseases and their families, not healthy people.

This means thousands of Australians are missing out on DNA testing that could be life-saving, and don’t know they’re at risk of a condition they might be able to prevent.

2. DNA screening could prevent different types of genetic conditions

There are measures people can take to reduce the risk for many genetic conditions. Once risk is identified through testing, people can enter risk surveillance programs, which are highly effective, especially for some types of cancer and high cholesterol. These can detect symptoms at an early (and more treatable) stage.

Some preventive medications can also reduce risk of breast cancer (tamoxifen), bowel cancer (aspirin), high cholesterol (statins) and genetic heart disease (beta blockers).

In some cases, preventive surgeries are available, such as mastectomy to significantly reduce breast cancer risk.

Read more: Angelina Jolie has had a double mastectomy, so what is BRCA1?

3. DNA screening would be cost-effective

We modelled the health and economic benefits of offering population DNA screening in Australia, focusing on young adults aged 18-25 years (about 2.6 million Australians).

Young adults are most likely to benefit from screening, being old enough to provide informed consent, but below the average age of onset for preventable adult genetic conditions, and below the average age of having their first child.

We modelled screening for four well-understood cancer genes. We calculated screening for these genes alone would prevent 2,411 cancers and save 1,270 lives in Australia over the populaiton’s lifespan, compared with current rates of DNA testing.

It’s possible some people won’t actually want to know if they are at heightened risk of disease. From www.shutterstock.com

At an estimated $400 per test, this would cost the Australian government around $600 million (four to five times more than current expenditure on genetic testing for these conditions).

But we estimated screening would save around $300 million in prevented cancer treatment costs, making DNA screening highly cost-effective in this population.

At $200 per test (which could be realistic in the near future), savings in treatment costs could outweigh screening costs, saving the health-care system money and saving lives.

Read more: Explainer: what is pre-pregnancy carrier screening and should potential parents consider it?

We also modelled the impact of providing screening results for family planning. This would identify “carrier” parents for rare genetic diseases that occur when children inherit two defective copies, one from each unaffected parent (such as cystic fibrosis).

Options like prenatal testing to identify affected pregnancies, or using IVF to ensure only unaffected embryos are implanted, are available to high-risk couples. Adding reproductive information to the model further improved the cost-effectiveness.

4. DNA screening raises ethical and regulatory concerns

Despite its potential to save lives and money, DNA screening raises ethical questions. Some people may not want testing due to concerns including DNA privacy, insurance discrimination or the “right not to know”. The shared nature of DNA also means testing implicates family members, and issues such as non-paternity may arise.

Those identified as high-risk by DNA screening may be stigmatised. Genetic discrimination already occurs in Australian life insurance, and evidence shows many people at high risk of certain conditions refuse testing for this reason.

Reproductive screening also introduces difficult decisions related to using IVF and termination of pregnancy. Ethical positions vary across religious and cultural groups, and must be respected.

Read more: Sharing isn't always caring: genetic privacy must come first

Making screening routine may also risk pressuring some people towards irreversible medical interventions, such as surgery or termination of pregnancy.

As a society, we must carefully consider these ethical issues. A recently-launched nationwide study will offer reproductive carrier-screening to 10,000 Australian couples to see if they are carriers of inheritable conditions. This will be crucial for building public awareness and examining these ethical concerns.

5. DNA screening will be feasible in the near future

As the cost of DNA testing falls, publicly-funded population DNA screening is becoming realistic. Genetic testing for risk of breast and ovarian cancer is already reimbursed on the Medicare Benefits Schedule in Australia for individuals at high risk, and more tests will likley be added in coming years.

If widespread testing is not provided by the health-care system, consumers will likely turn to cheap internet-based alternatives, which don’t necessarily follow Australian standards for scientific validity or quality.

Read more: Five things to consider before ordering an online DNA test

Population DNA testing through the health-care system would ensure higher standards of quality control. It would also facilitate equity-of-access to testing that is required to maximise population health benefits.

The federal government has already published guidance on population screening. But before Australia can launch a universal DNA screening program, we need more public education, regulatory protection, and increased funding to expand genetic health services.The Conversation

Paul Lacaze, Head, Public Health Genomics Program, Monash University and Jane Tiller, Ethical, Legal & Social Adviser - Public Health Genomics, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Would you consider DNA testing? Would you encourage your adult children to consider it?

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    To make a comment, please register or login
    11th Jun 2019
    A lot of the DNA sites are bullshit. My daughter got me a DNA test kit. It asked where was your mother and father born? I responded father UK mother Malaya.I done the swab test and It came back as 50% European and 50% Asian. My mother was European although born in Malaya. My daughter answered father born UK mother born UK. Her result 100% European. Explain that. When I queried it with them there was no response.
    11th Jun 2019
    I did a DNA test through My Heritage and one for my wife through Ancestry. Neither asked any questions, only provided answers, and found several close relatives we didn't know existed, as well as related links to long lost family members.
    11th Jun 2019
    A lot depends on how many other people have used the particular service, and how accurate the information that has been given to them by people who are getting DNA testing. Going through a site like ancestry.com is likely to yield better results simply because millions of people all around the world have used their DNA service, so that they have a large database of DNA that increases the probability of the results of the analysis of your supplied DNA being correct. The other thing is, that something like this is always going to have some margin of error, because DNA testing is still less than 50 years old.
    11th Jun 2019
    Actually it could cause a lot of panic, even suicides in some people who were serenely unaware that they carried genes that could make them very sick or shorten their lives.
    11th Jun 2019
    Ignorance is bliss? I don't think so. My mother and two nieces died from a genetic trait that could have been remedied with knowledge. Other family members have now been screened.
    How much would you scrimp to fatten up your superannuation if you knew you were never going to collect it?
    11th Jun 2019
    Scaremongering Triss.

    In the event this because a public health initiative, it is likely that the results would only be given by a health practitioner and not simply sent back to the person tested as happens with DNA tests from 'entertainment' sites like Ancestry.com.

    This is because for a start most people are not equiped to interpret the test results as likely risk factor, and second, most would have no idea how to mitigate an adverse result. These things would need to be done by a health practitioner and follow up scheduled as necessary.
    11th Jun 2019
    I can speak to this subject with knowledge. Firstly, reputable ancestry sites offering DNA testing for a fee will result in indications of genealogical associations (cousins). The larger the sample on the site the more"hits" are likely. I have mine on two sites and through one of those sites, Ancestry.com, I found details of my father's brother's sisters and parents (my cousins, uncles aunts and grandparents), all were unknown to me prior to the test. My father died fifty years ago, long before I was interested in my ancestors, and he was not in touch with his family, so neither were we. I also was able to discover that my father was born in a different country, on a different day, a different month and a different year, to the one that we celebrated as his birthday.

    Secondly, five years ago I suffered a permanent impairment, that upon investigation, was caused by a tumour. Although benign, the tumour was one of two, slow growing and would result in a risk of further impairment or death if not treated. I received radiotherapy. This particular tumour is caused by a gene fault from one of my parents, so I was DNA tested for this particular gene. It was confirmed that I was a carrier of this particular gene, which also makes me likey to develop endocrinal cancer. I was lucky as this gene usually causes the tumour and cancer problems at a young age. I have tests every six months to determine if there are any other tumours developing, and the condition of the existing tumours. The downside was that there is a 50% chance that my siblings and my offspring carried the same gene and the same health risks. Luckily, upon DNA testing I was the only member of the family who lost the lottery. However, if any were carrying that particular gene, they could have been monitored to prevent the same impairment that I have, happening to them, due to being able to have earlier treatment before any tumour growth had caused irreparable damage.
    11th Jun 2019
    The main issue is how secure are the results and whether insurance companies would get to know. As it is at the moment, if you have a DNA test for any disease you MUST inform insurance companies. This means that if your DNA suggests you may have a risk for say heart disease, the insurance company must be told and they can (and do) either increase your premium or refuse to insure you at all. Failure to tell them then have a heart attack they can refuse to pay out on the grounds it was an existing condition. The fact is, that whilst DNA is a useful tools, it speaks to tendencies not facts and that knowledge is a double edged sword.
    Karl Marx
    11th Jun 2019
    Oooo I can see the insurance industry, health insurance industry & health care providers salivating already in anticipation of being able to increase premiums etc & or make any risk found in your DNA classed on your contract as pre existing so you aren't covered under a normal premium base.
    I hope that legislation will prevent any company from enforcing DNA samples for health & insurance purposes.

    Tags: health, dna, disease

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