For some people, genetic information is formidably powerful. It can reveal that you have inherited a debilitating disease which lies unavoidably in your future, that you have a massively increased susceptibility to a particular cancer which can only be mitigated by surgery, or that you are not biologically related to your parents and siblings.
But, for many people, it’s actually quite mundane and uninformative. I’m one of those people. Undergoing genome-wide profiling was interesting, educational and worthwhile, and I would certainly recommend it as a voyage of exploration. But it hasn’t really been useful for my health. (It’s perhaps worth noting that a SNP profile covers only a fraction of the potential disease-causing variants, but nonetheless I doubt there’s anything I need to be scared of lurking in the rest of my genome.)
So, what did I learn?
From both 23andMe and deCODEme, I’ve discovered that, regardless of my own personal genetic risk, I’m at a distressingly high risk of various common diseases and a vanishingly small risk of numerous rare ones. This is certainly interesting from an epidemiological perspective, and one could argue that learning more about the prevalence of different diseases is one of the major educational benefits of personal genomics. But although I learnt a bit about the many diseases out there (and have marvelled at the fact that any of us are ever healthy), I haven’t exactly been moved to do anything as a result of my genetic information.
I’m at a higher risk of both types of diabetes relative to the general population, a fact which certainly could be useful if I (a) didn’t already know it from a distant family history of both diseases, (b) didn’t already maintain a healthy weight by eating well and exercising (fairly) regularly and (c) was really, honestly going to change my behaviour as a result of the information. Which, as we all know, is easier said than done. Intriguingly, my highest genetic risk is actually for rheumatoid arthritis (RA), but a little probing into the details indicates that this is primarily due to being homozygous for minor alleles of two closely linked SNPs (rs2476601 and rs667967) in the PTPN22 gene on chromosome 1… which is exactly the same gene that apparently underlies most of my genetic risk to type I diabetes. This left me wondering if I really am at higher risk of RA, or – given my family history – if in the context of my personal genetic background, this risk factor is more likely to manifest itself as diabetes. And this, of course, is part of the problem of trying to apply susceptibility variants uncovered in population studies to individuals.
On a brighter note…
It turns out that I’m at a substantially lower risk of age-related macular degeneration (AMD) than most people, which is certainly good news since this is quite strongly heritable, but not something I was losing sleep over to start with. (I’m well past the age to worry about type I diabetes, but well shy of the age where I might consider worrying about AMD!)
I don’t really seem to carry any of the common mutations tested for recessive Mendelian diseases, which lacking a family history in any of them is not exactly a surprise (though is still not definitive). Learning one’s carrier status is certainly something that seems potentially useful – particularly in conjunction with a partner prior to considering having a child – but for someone with no immediate plans to have children, the information is of rather limited relevance. Similarly, not currently being on any drugs, the pharmacogenetic information is little more than a curiosity to me, and I worked out years ago that I must be a fast caffeine metaboliser. (I am also unsurprisingly European by descent, but am pleased to discover that I might have blue eyes after all, contrary to the rather more persuasive phenotypic data…)
Don’t be surprised or disappointed by a ‘boring’ genome
Jokes aside, I have previously noted that many people feel rather under-whelmed by the experience of having a genome scan. But I would suggest that it’s the wrong message to take from the experience, and here’s why: if you go to your GP and ask for a health check, most people would be quite pleased to be told there was nothing wrong. I’ve taken home glucose and cholesterol tests, both with ‘normal’ results… this is good news, surely? So why be disappointed with an (apparently) uninteresting genome? If anything, I should be pleased. Of course, there is no such thing as being genetically normal – and I’m as much a mutant as the next person – but we shouldn’t expect to find hidden treasures in everyone’s genomes, nor skeletons in the cupboard. It’s just one of many molecules involved in the mind-bogglingly complex biological system that makes me me and you you. It might be useful in the future, and it might not. But either way it’s definitely interesting, and although that’s not a good enough reason for a health service to offer genome sequencing to everyone, it is a good enough reason to allow people access to a little personal genomic tourism if they want.
As technology improves and science progresses, we will understand an increasing amount about the genome; it will become a standard part of medical practice in many clinical contexts, and ever more individuals will have the opportunity to explore their own genetic information. But we shouldn’t assume that it will be useful for all – some people could benefit enormously right now from this kind of personalised genomics, and some people will never benefit directly. For now, what’s important is that we approach these tests with a realistic sense of what to expect, armed with good information, an open mind, and a healthy dose of common sense.