

Angelina Jolie at the 2010 Comic Con in San Diego (Photo credit: Wikipedia)Fifteen years ago it was the stuff of science fiction.  Now, you can just swab your cheek, send it to a company and, for only a few hundred euros, have your DNA analyzed.  You’ll find out about your ancestry and your predisposition towards certain inherited diseases or conditions (from cancer and diabetes to myopia).  You’ll also learn if you’re a ‘carrier’ — that is, if you’re carrying a gene that won’t affect you but might affect your children.  You can even get information about more light-hearted issues like whether you’re likely to have fast- or slow-twitch muscles or your ability to taste certain bitter flavours.  The technology is pretty great, but it also raises some interesting questions which I thought would be worth discussing (especially since I really enjoyed our previous discussion).

At the moment, sequencing an entire genome is still expensive enough to be out of most people’s reach.  Instead, most personal genomics companies offer genotyping services.  Unlike sequencing, where all three billion letters of your DNA are read, genotyping involves looking at 500,000 or a million locations in your genome.  The locations are chosen because they’re close to genes known to play a role in certain characteristics or diseases or because variation at that location is statistically linked to a disease or trait.  By reading a few letters of DNA at these locations, scientists can find out which variant a person has.

For example, a person with “GG” at a particular location might have a higher chance of having blue eyes, while someone with “AA” at the same location would likely have brown eyes.  It’s not really that simple, though.  Eye color, like many other traits, is based on lots of genes which interact to determine the actual color.  It’s important to realize that genotyping doesn’t give you definite answers — you just get the odds.  Knowing how to interpret those odds is important, too.  You might be twice as likely as average to develop a certain disease, but if the average person has a 4% chance, your odds would still be pretty good.  You’d have an 8% chance of getting the disease, meaning that 92 of 100 people like you wouldn’t actually get sick.  Conditions like diabetes can also be strongly influenced by lifestyle choices.  Knowing you’re at risk can help you make better decisions, as long as you understand how to evaluate the numbers.

Despite the caveats, this sort information can be quite important; it can even change your life.  The actress Angelina Jolie recently decided to have a double mastectomy after a genetic test confirmed that she had a high chance of getting breast cancer.  She discovered that she was carrying a mutant form of the gene BRCA1 which normally repairs DNA.  The mutation made it more likely that she would develop breast or ovarian cancer, giving her odds of 87% and 50%, respectively.  Based on her family history, she decided to undergo the surgery as a preventative measure.  Following the operation, the likelihood of her developing breast cancer dropped to under 5%.

You’re not just learning about yourself, however.  You’re also learning about your relatives, since they share some of your genome.  Parents and children share 50% of their genes, as do full siblings.  If you’ve got a mutated version of a particular gene, there’s a 1/8 chance that your cousin has it, too.  Finding out about your own genome can mean inadvertently invading other people’s privacy.  Even if you don’t tell your relatives what you’ve learned, you might change your behaviour in ways which would tip them off.  Do you have the right to make that decision for them?  At what point do our individual rights give way to the rights of others and communal considerations?

I think this is pretty exciting technology and I’d love to get genotyped or, better yet, have my whole genome sequenced.  The question I’d like to pose is: Would you like to get genotyped or have your genome sequenced?  I’m not really asking about the issues of insurance, etc, here, but we can discuss them if people want.  I’m more curious about things like:

  • Are you interested in finding out more about where your ancestors came from and what percentage of your DNA comes from Neanderthals?
  • Would you just want the fun bits and none of the scary/important health-related stuff? Or maybe you’re only interested in the serious stuff?
  • What about incurable conditions like Parkinson’s or Huntington’s?  Would you want to know if you’re more likely to develop them?  Would you change your life if you were?
  • Given that you’re finding out for your whole family, would you ask for their consent? Do you think they should have a right to veto your decision?
  • What about your partner — would they get a say?  Do you have an obligation to tell them about what you might pass on to your children?