This story appeared in Techonomy’s Winter 2020 magazine.
While genetic testing and genome sequencing are still considered cutting-edge by consumers and physicians, scientists have moved well beyond simply querying DNA to understand our health. The fruits of that research are already reaching the clinic, and may even become mainstream in the not-too-distant future. If you think there’s a lot of healthcare data about you floating around now, just wait.
One simple way to understand what’s coming next is through what biologists refer to as the “central dogma”: DNA makes RNA makes protein. Your genome, which contains the DNA you inherited from your mother and father, is your body’s blueprint. It dictates everything from day one, but cannot change to react to any particular situation in your life or environment. The way anything actually happens in your body is that each snippet of DNA, or gene, undergoes a molecular process to make RNA. This RNA is much more dynamic, representing only the genes that are turned on at any given time. (Many genes, for example, dictate the development process that turned you from a single cell into a baby with 10 fingers, 10 toes, and organs in the right places. Once those genes complete their purpose, they’re never turned on again.) RNA, in turn, guides the formation of proteins, which actually do the heavy lifting of virtually all tasks required to keep you humming along. They’re changing all the time.
Scientists have found that across this DNA-RNA-protein spectrum, there are many opportunities to peek into the body for a better view of health and disease. Here are some examples:
1. Genes and Genomes
This is what you’ve heard about most, since these are already used in the clinic. Labs can analyze individual genes, sets of genes, the subset of your genes that translate into proteins (this is called an exome), or the entire genome, which is the full 6 billion molecular blocks that make you unique. DNA reveals whether you have an inherited risk for a disease such as cancer, the cause of a rare disease, and other details that were baked in from conception.
Because RNA only reflects genes that are active, it can provide a more useful view of what’s going on in your body at a particular point in time. Measuring RNA, also known as gene expression, can help explain disease conditions that don’t show up in your DNA. For instance, some diseases are caused by RNA toxicity, which means that what can be a normal piece of DNA has been processed into too much RNA.
These perform just about every chore required by the human body. They’re also fleeting, typically lasting only as long as they’re needed before they break down. That’s why many scientists believe they offer the best real-time snapshot of your health. From your immune system’s response to an infection, to red-flag alerts that an organ is failing, proteins may offer measurable signals that could not be found with DNA. One day, a test may look at all the proteins active in your body; this is called the proteome. Already, simple proteomic tests are being used by some doctors and hospitals.
Not to be confused with an exome, exosomes are teeny-tiny particles that cells use to communicate with and influence each other. Think of them as molecular email: a cell might stuff specific DNA, RNA, or proteins into exosomes and fire them off for certain other cells to receive and decode. These particles may help researchers track the spread of cancer, understand an ongoing immune response, and more. One of the reasons they’re so appealing for potential clinical use is that they can be found in blood, urine, and other easy-to-access samples.
5. Cell-Free DNA
Our bodies are not the pristine machines we tend to picture. Research has shown that as cells die, they split open and spill out their molecular cargo. While that released DNA no longer has any effect in the body, it can be accessed for clinically important questions. So-called “cellfree DNA” is the scientific basis for non-invasive prenatal testing — blood samples from a mother include DNA sloughed off by the fetus. It’s also a way to peer into a tumor, which litters the blood with spilled-out DNA. Early testing has shown that circulating tumor DNA can be used to select a cancer treatment without making the patient undergo painful surgical procedures.