What DNA Can And Can’t Tell Us
The recent piece by Lisa Milbrand in Parents Perspective provides a fascinating glimpse into the modern world of DNA testing. In this post-genomic era, DNA may be thought of as something of a biological crystal ball. But it’s worth noting that the crystal ball may be quite blurry depending on what we are looking for.
Take for example rare diseases that are, in essence, genetic diseases. In this case, DNA tells us almost everything we need to know. If you have the gene variant that is responsible for the disease, you know that you will get the disease (although you won’t know exactly when). Such is the case for Huntington’s Disease along with many other single-gene diseases. That’s why babies can be screened for Cystic Fibrosis.
Other diseases are a little more blurry. If you carry a certain genetic variant you may be at high risk for disease but without perfect prediction. An example is the BRCA genes and breast cancer. These can carry risks along the lines of 85% (note not 100%) that you will develop breast cancer. Other genetic markers can operate in this probabilistic way.
But it’s worth remembering that most diseases – and in fact most human traits – are not due to the actions of a single gene. Multiple genes come into play, many (if not most) of which have not been identified. Multiple environmental factors come into play as well. Then of course there are the nearly infinite combinations of how genes and environments interact. That’s the stuff that makes the DNA crystal ball fuzzy indeed. The reality is that family history – rather than DNA testing – can probably tell you more about your (and your child’s) genetic risk for disease – and that the environment will be as telling. If you are wondering if your child will be very shy, or very outgoing, or somewhere in between, certainly their DNA holds some clues – but these aren’t easily revealed or understood. And they are the only determinants.
So if you consider DNA testing for yourself and your offspring, bear in mind what it can tell you, and what you want to know. Many times the answers just won’t be there.Add a Comment