Your genetic markers
An important discovery of the past decade is a set of about 10 million places in everyone's chromosomes where the genetic code often differs by one letter — for instance, a G is swapped for an A, or a C for a T. These single-letter differences can be used as flags or markers for nearby genes that affect your health. They are called SNPs (pronounced "snips," short for single nucleotide polymorphisms).
By looking very closely at your complete genetic code, your genome, it's possible to see, for each location, whether you have the genetic letter associated with an increased risk of a particular disease.
To see which markers you have, our laboratory floods your DNA across a specially designed silicon chip. The chip has been primed to look at almost a million SNPs.
Any disease-associated markers you inherited from your parents put you at higher risk for the conditions associated with those markers. If you have the risk marker connected with obesity, for instance, you are more likely to become obese during your lifetime. You may also inherit markers that protect you from certain health conditions.
The concept behind the science of finding disease markers is fairly straightforward. Take thousands of people with a medical condition, and thousands of similar people who do not have that condition. Compare their DNA and identify places where one version of a marker is much more common among the affected people than the healthy people. Then we know those markers are either on or close to genes that drive up the risk of that condition.
