I will run through the questions while I am waiting for my deCODE cancer scan and my NHS BRCA test. There are two sets, I’ll answer the first in this post.
1. Why am I considering taking this test?
I'm taking the test because I'm interested in consumer genetic testing and in sharing the experience, I'm also intrigued to know what my cancer markers have in store. DeCODE do not test for BRCA genes but for common variants (SNP markers) that can increase risk three fold from average (that is up to 37% lifetime risk, compared to the more dramatic 55-85% risk for BRCA). The deCODE information is to some extent complementary to BRCA testing, all be it less clear cut.
I have no immediate medical motivation to find out about risks for cancers other than breast, given that I am under 40, have a reasonably healthy lifestyle and no untoward family history. I am, however, very excited about being part of the consumer DNA experiment and fascinated by the implications for society. I would love to have my complete DNA sequence but I’m happy to wait until sequencing costs come down and science fills in some of the gaps.
I have been researching the rival screens sold by 23and me, which I admit to finding tempting, the full list of tests is here. The trivial stuff (such as memory, pain sensitivity, avoidance of errors etc) is alluring in a pop psychology kind of way, the drug response information would be useful, the ancestry tracking looks enticing and now I’ve had my kids I could cope with the carrier status data. It does all seems slightly shallow, and drilling down to the disease information details reveals fewer markers than deCODE, which would explain the cheaper price. But overall it gives me that tingly hover-over-the-buy-it-now button feeling that precedes the desire to purchase something expensive online.
2. What do I hope the test will tell me?
I hope that I will have a low or average risk profile for breast cancer, and a low risk for the other cancers.
3. How important is it to know what the test may tell me?
Taking breast cancer separately, the outcomes could be crudely divided into 4:
a. Low deCODE marker risk - High BRCA risk
b. Low deCODE marker risk - Low BRCA risk
c. High deCODE marker risk - High BRCA risk
d. High deCODE marker risk - Low BRCA risk
[Although for the deCODE markers I’m unlikely to get results as clear cut as high/low risk, but numbers in between]
Using this to answer the question:
Scenarios a and c – deCODE test not that important compared to positive BRCA
Scenario b – deCODE test adds some extra reassurance
Scenario d – despite not having BRCA, a high deCODE score would reinforce my family risk
I’ve crudely defined “importance” as how much I’d change my behaviour. Based just on my family history I’m already trying to lower my risk (diet, exercise, self-examination), but I’m not hyper-vigilant - a high risk for either BRCA or deCODE markers would lead me to investigate early scans and preventative medicine. However, the whole hog mastectomy/ovary removal option could not be justified on the basis of profiling SNP markers. Would the NHS offer me breast scans at a younger age if I am low risk BRCA but high risk according to deCODE?
4. Will the test be able to answer my question?
The tests will give me more information on my cancer risks, but I'll wait to find out if they will add much more to my risk profile over and above that already in my family history.
5. What do I hope to be able to do after getting the test result that I can’t do now?
If I have high risk deCODE markers then I will take action (but perhaps I should be suitably motivated by my family history). In terms of the other cancer types, having a higher risk of skin cancer would make me more away of the amount of time I spend in the sun.
6. What if I get a result that I am not expecting?
I am expecting to be moderately high risk for the deCODE breast cancer scan, but not to be in the top risk band (that would involve markers from both sides of my family, and my mother’s relations have no history of early onset breast cancer). Being in the top band would take some getting used to.
It would be a shock to be higher risk for the other cancers for which I have no family history – I have the mindset that I am low risk for these.
7. Would it be a good idea to get professional advice (e.g. from my doctor) before buying the test and if so how can I get it?
I saw my GP to get referred for the BRCA test. I didn’t ask about the deCODE test but I doubt he would have recommended it or even been particularly familiar with the genetic markers involved.
8. Will the information the test provides have implications for my relatives?
The BRCA test will have more implications than the deCODE markers for my children and sibling, plus the children of my affected aunt. But the SNP risks will still be relevant to my immediate family, especially if there are any increased risks.
9. Am I going to tell them? If so, how?
I’m hoping the results are low risk so I won’t have to deal with this – if they are high then I would tell my brother (but would he want to know?). My sons are too young now which postpones the decision. They are likely to have access to their own DNA sequence by the time they are old enough to understand. If they were older now? I'm not sure I would say anything until they were adults, and I worry about the scope for nagging refrains such as “with your DNA your really must eat your broccoli”.
10. Will they want to know?
I can ask my brother if he wants to know, but I will only ask if there is a high risk, so the act asking may change his answer. Although, of course, I am blogging about the results...although I don’t have to blog ALL the results. Thankfully kids too young to read the blog...
11. Ought I to discuss this with them beforehand?
Hmm, too late now. Buying the test was very much like buying anything else on the internet, an individual consumer decision: it's my DNA and I can do what I want with it. This is even embedded in the company brands – 23andme, deCODEme. But buying a DNA test is actually one of the few consumer decisions that is not me me me.
12. Do I need to take the test now?
I could wait for the price to come down and the science to progress, although the BRCA test is urgent as I’m older than my grandmother was when she was diagnosed.
13. Is there another way of finding this information out?
Arguable my family history gives as much information as the deCODE markers are likely to. There are swathes of studies correlating the SNP markers to disease sufferers, but are there any correlations between markers and the family history of healthy individuals – i.e. which is more predictive of disease outcome – looking at common SNPs or looking at family history? It somewhat depends on the size of your family – expansive extended families contain much more data.
14. Would the result of the test have any impact for my work or my insurance prospects now or in the future?
There is currently an insurance moratorium regarding use of genetic information in the UK. I’m self-employed but don’t see that an employer would need to know.
Posting answers to these questions has forced me to think about the test in more detail than had I worked through the responses in my head. I suppose this has been a DIY genetic counselling session. Nothing similar was pushed at me when I ordered by kit from deCODE, which makes sense from a commercial point of view, but I wonder if some families have struggled with nasty genetic shocks that they weren’t expecting.
Comments
Post a Comment