A common misperception about genetic mutations is that they all cause disease. They don’t. Some mutations, which are changes in genes that are also called variants, make it more likely you will experience a particular disease, but it is not a guarantee.
An even less understood fact is that some mutations appear to provide protection from disease. As the study of genetics advances, we can focus more attention on the protective benefits of genetic changes. This will provide an opportunity to create a better balance in medical and clinical science with the gene changes that increase risk for disease.
Geisinger genetic counselor Marci Schwartz, LGC, is a key team member in the MyCode® Community Health Initiative and provides us with a short history of the evolution of genetics and the possibilities for the future:
Our understanding of human genetics has advanced rapidly over the last century. Just 107 years ago, the term gene was coined. Since then we have discovered the molecular structure of DNA, learned to read, or sequence, our genetic code and discovered thousands of genetic causes of disease.
However, we still have an incomplete understanding of how DNA sequences relate to human health. Interpreting our genetic code can be like trying to read a book in a foreign language when you only understand some words — at times it is easy to know what a sentence is saying, but sometimes it is a lot more challenging.
Because of this interpretation challenge and how expensive DNA sequencing has historically been, in the past sequencing of genes was reserved for those who were believed to have a genetic cause of disease — and the focus was on looking for genes that do not work correctly and cause health problems.
Now the cost of DNA testing has come within reach for many more uses, including sequencing of healthy people’s genes through research projects like the MyCode Community Health Initiative at Geisinger. This means that we have enhanced potential to do research to better understand how DNA influences health and to begin to think of new uses for genetics in healthcare.
One potential new use for genetics in healthcare is the consideration of gene mutations that put a person at decreased risk for disease. Right now, there is no standard for looking for and reporting on protective genetic mutations in people who have genetic testing. We also have limited knowledge of which genetic sequences may be protective for different conditions.However, there are a few ways that we can foresee how protective genetic information could be beneficial in the future. For example, this type of information could help us better understand why some people develop disease and others do not.
One early example of protective genetic information that could be promising for use in clinical care relates to risk for coronary heart disease. In particular, we now know that one gene called PCSK9 has the potential to either increase or decrease the risk of heart disease by influencing the level of LDL cholesterol in the blood — depending on how the gene change affects gene function. Protective variants in this gene can explain why some people have a lower risk for heart disease than we would otherwise think.
We also know that some people have a genetic condition called familial hypercholesterolemia, in which there is an increased risk of heart attack and stroke from exposure to high cholesterol from an early age. It is possible that some people may have inherited both a genetic variant increasing their cholesterol levels and another decreasing their cholesterol levels. This type of information might be helpful to explain why some people may have different traits than expected or why family members differ from one another.
Improvements in the accuracy of risk predictions using protective genetics could help increase patients’ confidence in genetic information and significantly expand the use for genetics in healthcare.
Marci Schwartz, LGC, is genetic counselor and research coordinator in the Genomic Medicine Institute at Geisinger. She is interested in the use of genome screening as a tool to improve preventive medical care in a personalized way.