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Primary Genetics

Polygenic risk scores are a new type of genetic test designed for common conditions like diabetes, hypertension, and heart disease. Primary care physicians may want to ask some key questions about the tests before using them with their patients.


How do these scores differ from other hereditary disease testing? 

Common diseases like diabetes, hypertension, and dementia are usually caused by a combination of many genes and lifestyle or environmental influence and are therefore distributed more evenly in the population. Advances in computing, like artificial intelligence technologies, are enabling labs to develop proprietary risk scores for common diseases. These new “scores” compute a genetic risk for a common condition by adding up the influence of many genes.


How should physicians use genetic risk scores?

It depends on the particular test, but risk scores for common diseases will often label a result in a risk category like “high”, “average”, or “low” risk. A physician can add this risk factor to the mix of lifestyle and environmental risk factors when creating a medical plan for a patient.

Keep in mind that these scores are unlikely to address the less common single-gene forms of the conditions tested. Family history can help guide which type of inheritance is present in the family.


Are genetic risk scores trustworthy?

Again, it depends on the test and the lab.  Risk scores are usually developed by a particular laboratory and are therefore proprietary. Given the limited regulatory oversight of genetic testing, risk scores may not have undergone outside review. Physicians can ask for the lab to provide evidence for clinical validation, which means that a test result is clearly correlated with the disease state.


 It is important to distinguish for the lab what type of validation being sought. Most CLIA-certified labs have good analytical validation for a test, which confirms that the lab process is consistent and repeatable. Not all labs have collected rigorous evidence for clinical validation.


Will polygenic risk scores be part of whole genome sequencing?

Scores generated require an algorithmic approach rather than only looking at DNA sequence. Therefore, a lab’s proprietary algorithm will probably only be available through that particular lab.


Sources:

1. Torkamani, A, Wineinger, NE, Topol, EJ. .The personal and clinical utility of polygenic risk scores. Nature Reviews Genetics 2018, 19:581–590.

2. NIH Genetics Home Reference “How can consumers be sure a genetic test is valid and useful?” accessed July 24, 2019 at https://ghr.nlm.nih.gov/primer/testing/validtest.

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