Dear Danaher, Why don’t we have a DNA test for everything?

Dear Danaher is a column featuring reader-posed questions, answered by Danaher experts. Do you have a question about the future of science and healthcare? Send it to ask@danaher.com

Dear Danaher,

As someone who came of age during the boom of personalized everything, I assumed DNA testing would be a crystal ball for my health. I figured by this point in my life, I’d be able to take a simple test and know what diseases I would face and how to prevent or treat them. Why hasn’t that become a reality yet? What’s holding us back?

Sincerely,

Testy in Tuscaloosa

Dear Testy,

Scientific accomplishments are rarely the stuff of international press events, but in 2003, the completion of the Human Genome Project was a celebrated event worldwide. The massive, global scientific undertaking to sequence more than 90% of the human genome took 13 years, countless scientists and incredible support from research institutions and governments. The language of genes and gene editing even took over pop culture in the late 90s and early 2000s—think movies like X-Men, Jurassic Park and Gattaca.

More than 20 years later, we’ve actually made some major strides toward the vision you describe. Advances in human health and our understanding of disease have been evolving at an exponential speed with new discoveries, technological advances, tests and therapies developed every day.

However, the deeper we delve into the human body, the more complex it becomes. Most diseases aren’t the result of a single mutation, but tens or even thousands of mutations working in concert. Additionally, the breakthrough of single-cell analysis has shown us that with many traditional methods, we are sometimes observing a “bulk” effect from all the different cell types present in the sample, including healthy cells, tumor cells, matrix cells and more, which makes biological interpretation difficult.

That’s why a lot of recent advances have turned toward understanding diversity—both of types of cells and within each cell.

Your cells may all have the same DNA, but cells can interpret genetic instructions in many different ways. Just as the same recipe in the hands of two different cooks can turn out wildly different, cells interpret the same DNA differently based on how the DNA is packaged (epigenetic signatures), environmental signals and lots of other factors.

That’s why scientists are now not only looking at DNA, but also at the proteins made in the cell. The idea here is that by studying the proteins, you are looking not just at what instructions exist, but how they have been interpreted. This field is called “proteomics”—like genomics, but for proteins.

Naturally, the complexity doesn’t end there. (Sensing a theme?)

First are the sheer numbers. Humans have around 20,000 protein-coding genes, but through processes like alternative splicing, that number explodes to potentially hundreds of thousands of proteins that can be produced by a given cell.

Next, we need to consider not just which proteins are present, but where exactly within the cell they’re located. This takes the proteome one step further into a burgeoning field called “spatial proteomics.” Our favorite analogy for this way of thinking comes from our collaborator Emma Lundberg, a Stanford scientist who describes a cell as a house with many different rooms. Just as you might do different tasks based on whether you’re in the laundry room, kitchen or bedroom, the same protein can have different effects based on where in the cell it is.

Before you get too overwhelmed by the scale of the challenge, there is good news: we’ve developed new technologies to capture and make sense of all this complexity.

The first are improvements in a foundational technology called mass spectrometry, which is commonly used to measure and analyze proteins in a sample. Mass spec, as it's called, has undergone exponential advances in versatility, sensitivity and capability, transforming from a niche analytical technique into a cornerstone of modern proteomics, metabolomics, and many other scientific disciplines. The technology enables smarter analysis that can pinpoint changes called post-translational modifications, which is one way that cells can alter the function of proteins after they are made and are often used to designate what part of the cell the protein should be working in.

Smarter microscopes are also helping scientists get a fuller picture of where proteins are located in a cell. For a protein to appear in an image, it typically needs to be tagged or stained, which limits the number of proteins that can be studied in any given image. But new workflows and microscopes, including those powered by AI, are improving the sensitivity and analytical power of techniques that let scientists identify thousands of proteins in the same image, even with few or no specific tags. These advances in imaging are akin to moving from only being able to search a document for a particular word to being able to read the entire thing in context.

If that all sounds exciting, that’s because it is. Spatial proteomics was even named Nature Method’s Method of the Year in 2024.

Of course, just like genetics, proteomics and spatial proteomics are only one piece of the puzzle of human health. Even though we often can’t rely on one-and-done genetic tests to tell us everything we need to know about disease, scientists have never shied away from complexity—or from finding answers that will make us all healthier.

Warmly,

Danaher

Many thanks to Katherine Tran and Alexander Weis for providing the insights used in this answer.