Genetic markers
Our genetic code comes with many variations – some can cause rare genetic conditions while others can contribute to common, complex diseases.
The concept behind locating genetic markers, also known as SNPs, 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 variation of a marker is much more common among the affected people than the healthy people.
These SNPs may not actually cause the condition, but we know they are either on or close to genes that increase the risk of that condition and are therefore used as markers of increased predisposition to that condition.
To select the health-related markers included in our genetic testing services, our team of Ph.D. geneticists and epidemiologists applies strict inclusion criteria.
In curating the peer-reviewed literature, our team looks for genetic risk markers that are significantly associated with clearly defined health conditions. Our criteria for inclusion include:
- The association between the SNP and the disease has been replicated at least once in the same ancestral group. If the condition has been studied more than twice, the preponderance of evidence must show the same statistically significant result.
- The study is well-designed with sound epidemiological principles, the cases are defined using standard clinical diagnostic techniques, and the controls are taken from a similar source population as the cases.
- The sample size is large enough to detect even weak effects.
- We critically evaluate the significance level of each reported SNP, taking into account the stricter significance levels needed when multiple testing is performed.
- The researchers use sound laboratory practices.
Medication outcomes must also meet strict guidelines:
- For the medications included, the risks must be ones that you or your doctor can act on or do something about. Your risk of side effects can be minimized or drug effectiveness can be maximized by using a customized dose, for example. Or in some cases, you might be better suited to another medication altogether.
- Research findings from multiple well-designed studies have to show consistent, reliable, and significant association between a genetic marker and a medications outcome.
- The genetic marker connected with this medication can be tested using the DNA in a person’s saliva. Some other types of medications tests might use DNA from tissue related to a disease, such as cancer cells or harmful viruses. Navigenics only tests DNA that can be obtained from a person’s saliva sample.
Functional data and magnitude of effect are also taken into account, but studies are not automatically excluded if functional data is unavailable or the effect estimate is small.
You can learn more about our selection criteria for markers, including our risk model score.