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Predictive Genetic Testing: Assessing Polygenic Risk
July  2019

A recently published article provided an update on the state of predictive genetic testing.

This is not referring to the testing of single gene mutations that you might know as BRCA 1 or BRCA2, but rather the genome wide association studies (GWAS) that hunt for single-nucleotide polymorphisms (SNPs) on multiple genes that can be associated with increased risk for developing cancer, coronary artery disease, type 2 diabetes, etc.

More than 70,000 associations between SNPs and diseases have already been identified. The growing amount of data has resulted in several polygenic risk scores (PRS). As the data set gets larger, it is becoming less likely that significant SNPs have been missed, although most studies have had a preponderance of people of European origin.

Groups are actively working to standardize data to do even larger association studies on less common conditions. So far, the studies have reinforced the multifactorial nature of most common diseases with diet, exercise and environment playing a large role in their development. However, it appears that risk can be stratified effectively with those
having the higher PRS having multiples of risk over those with the lowest. This all varies by disease and risk score.

This is all still a work in progress as it is too early to tell if polygenic risk can be changed, and if so, by what method. Will environmental and behavioral changes be effective in reducing risk? Or will study of strongly associated SNPs result in new medications that will reduce risk? Only time will tell so stay tuned.

In this issue, we also have a case of myocardial bridging by Dr. Kadouch and splenectomy by Dr. Rooney as well as our usual ECG Puzzler.

Hunter DJ and Drazen JM, “Has the Genome Granted our Wish Yet?”, May 15, 2019

Buniello A, et al, “The NHGRI-EBI GWAS Catalog of published genome-wide association studies, targeted arrays and summary statistics 2019” Nucleic Acids Research 2019:47(D1);D1005-D1012.