Everyone inherits their genes from their parents -- one copy from each -- but changes to a gene or set of genes don’t always have the impact on your health that you might imagine.
That’s because single genes rarely act alone. Instead, they exert their influence by working in coordination with each other. When scientist talk about “genomics,” they’re referring to analyzing all of the genes that someone has.
So what is genomic medicine? In short, it’s the study of the collective impact that all of a person’s genes has on their body.
Genomic medicine is a relatively new field, but it has grown quickly over the past few decades. This area of medicine took off after the Human Genome Project, a massive scientific endeavor, was completed in 2003. The Project aimed to fully map and understand all the genes that humans have. The scientists working on it discovered that we probably have about 20,500 genes.
When you put all of your genes together, you have your genome: a full set of instructions that tells your body how to grow and develop. These instructions come in the form of DNA. Sections of DNA are combined to form genes.
Genomic medicine is already helping scientists learn who might be at risk for certain diseases, including cancer and rare childhood diseases. It also has the potential to help match patients to the treatment they’re most likely to respond to.
Genetic Medicine vs. Genomic Medicine
“Genetics” and “genomics” are sometime used interchangeably, but they’re not the same. Genetics refers to the specific genes you’ve inherited. The study of genetics focuses on individual genes and how they function.
You might have heard that mutations (changes) to a specific gene can set you up for certain health problems, which is true. People who carry a BRCA mutation, for example, have a much higher than average risk of developing breast and ovarian cancer. If you’re worried about your breast cancer risk, you might want to ask your doctor if you should have a blood test that checks for this mutation.
Genomic medicine, in contrast, is far broader, because it entails having all of the DNA in all of your genes mapped out in a process called genomic sequencing. While that sounds more complicated -- and it is -- recent advances in technology have made it more affordable.
Your Genome: Uniquely You
Being human means that your genome is almost identical to the genome of any other human being -- but not exactly. A tiny fraction will be different, which explains why we don’t all look the same or have the same health issues. Some of these differences are inherited, but others come from the impact your lifestyle and environment have on your genes and change how they are expressed (epigenetics).
Variations in your personal genome might explain why you’re at higher risk for certain diseases, or how well you’ll respond to a specific treatment. They might even help a doctor diagnose you with a particular ailment. Because this is a new and developing field, however, practical uses are limited. For now, having your genome sequenced is most likely to be useful for people with certain types of cancer or rare, undiagnosed diseases.
Should You Have Your Genome Sequenced?
There are now more than 6,000 conditions that could be diagnosed with the help of genomic sequencing. Although that sounds like a big number, you should know that most of these conditions are rare. That’s why it is most likely to be useful for explaining why someone has many congenital health problems or moderate to severe developmental disabilities -- especially if getting a correct diagnosis impacts how those issues are treated.
Genome sequencing may be useful if you have a child with a serious condition doctors haven’t been able to diagnose. It is possible that getting your child’s genome sequenced might help pinpoint why they have intellectual disability, developmental delay, seizures, limb abnormalities, frequent infections, or other issues.
Some cancer patients also benefit from having their genome sequenced. For instance, research suggests this method is more useful than traditional genetic tests (which only check for a few specific mutations) at matching blood cancer patients to the best treatment for them. This is the crux of precision medicine, an approach that enables doctors to tailor treatment to a patient based on variations in their genes (or, in the case of cancer, the genes found in cancerous cells) as well as other factors.
If you have cancer, you might want to ask your doctor if you should consider genome sequencing. Depending on your type of cancer, it’s possible that sequencing could reveal information that would help you choose a treatment or provide insight into your prognosis.
What Are the Pros and Cons of Genome Sequencing?
Genomic medicine is very exciting, and there are now several companies that will sequence your genome if you want to pay for it. Going this route has some potential benefits. If you learn that you have a genetic predisposition to heart disease, for instance, you might make lifestyle changes that’d lower your risk.
There are, however, several potential downsides worth considering. For starters, scientists don’t yet understand the role of most of the genes in the human genome, so your test might find variations that have no known meaning.
You might also think about the possibility that such a test could result in information that’s distressing. If you found out that you’re going to develop a fatal disease that has no cure, would you want to know? Some people might, but others might find that it only leads to them becoming depressed or anxious.
Lastly, you should consider whether you’re OK with a private company having access to all the information that’s contained in your genome. Be sure to read their privacy policies carefully. Keep in mind that since this is a fairly new field, some companies may be still sorting out best practices for keeping your info safe.