What you need to know
About 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 disease 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.
How we select markers
Our team of Ph.D. geneticists and epidemiologists scours the peer-reviewed literature to identify genetic risk markers that are significantly associated with clearly defined health conditions. Our inclusion criteria for each SNP include the following:
- The association between the SNP and the disease has been replicated at least once in the same ethnic group. If the condition has been studied more than twice, at least 60 percent of the studies must show the same statistically significant result.
- The study is well-designed with sound epidemiological principles, case definition using standard clinical diagnostic techniques and controls taken from a similar source population as the cases.
- The sample size is large enough to detect even weak effects.
- The study meets a minimum level of statistical significance and uses a sound method to analyze the data. Analysis includes an evaluation and adjustment for population stratification and possibly other confounders that may lead to spurious results.
- The researchers use sound laboratory practices.
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.
How we select conditions
Because our goal is to help individuals lead longer, healthier lives, we focus on conditions where an outcome may be modified by either lifestyle factors or supervised medical management. This includes both primary prevention and earlier diagnosis for improved long-term management.
How we estimate risk
We incorporate several factors into estimating an individual's lifetime risk for each health condition, including:
- The gender-specific lifetime risk of that disease in the general population
- The frequency of the disease-associated genetic marker in a reference population
- The odds ratio of that genetic marker as defined by the original research
- The individual's genetic markers
- A standard multiplicative model for combining multiple risk factors
Our methods and sampling process
- Navigenics contracts with a CLIA-certified lab to provide our members with the highest quality in laboratory specimen handling.
- Individuals provide Navigenics with a saliva sample from which their DNA is extracted and then interpreted at more than a million points in the genome.
- Once an individual's DNA is interpreted, Navigenics estimates their lifetime risk for specific common diseases, which is then presented to the individual in a secure, Web-based report.
- The report can easily be printed to facilitate discussions with health-care providers.
