What are genetic markers?
When it comes to health, scientists have learned that about 10 million points in the human genetic code are especially important. At these points, the genetic code from person to person often differs by one letter – for instance, a G is swapped for an A, or a C for a T. In some cases, the code includes one extra letter (two C's instead of one, for instance, called an insertion), or one letter fewer (known as a deletion).
These differences can be used as flags or markers for nearby DNA that affects your health. They are called SNPs (pronounced "snips," short for single nucleotide polymorphisms).
By looking very closely at your complete genetic code, it's possible to see, for each location, whether you have the genetic letter or letters associated with an increased risk of a particular disease.
Any disease-associated markers you inherited from your parents put you at higher risk for the conditions related to those markers. If you have the risk markers connected with diabetes, for instance, you are more likely to develop diabetes during your lifetime. You may also inherit markers that protect you from certain health conditions.