Have you ever heard a doctor mention your “genome” and wondered what that actually means? You’re not alone. In this article, we’ll break it down in plain language — and explain how understanding your genome might help you get answers about your health.
Your Genome: What It Is and Why It Matters
You’ve probably heard of DNA — the material inside your cells that carries information about who you are. Your genome is simply your complete set of DNA. It includes everything encoded in your DNA, from the color of your eyes to how your heart and lungs develop.
Within your genome are roughly 20,000 genes — segments of DNA that carry instructions for making the proteins your body needs to grow, function, and stay healthy.
Genes make up only about 1–2% of your total genome. The remaining portions contain important signals that control when and how genes are turned on or off — and changes in these areas can also affect your health.
While every human genome is about 99.9% the same, that small 0.1% difference between people is what makes each of us unique. It also means that some people carry genetic changes that can affect their health — sometimes from birth, and sometimes showing up later in life.
What Are Genes, and How Do They Affect Your Health?
Genes are like individual sentences within your instruction book. Each gene carries the “recipe” for a specific protein, and proteins do the work of keeping your body running. When a gene contains a change that affects how the protein is made — or whether it’s made at all — it can sometimes lead to a health condition.
These genetic changes can be:
- Inherited from one or both parents
- New (de novo), meaning they occurred for the first time in you, without being passed down
- Present in some cells but not others, which can happen with certain conditions
Not every genetic change causes a health problem. Many are normal variations that have no effect at all. A genetic specialist can help make sense of what a change actually means for your health.
What Is Whole Genome and Whole Exome Sequencing?
When your provider orders genetic testing, they have several options. Some tests look at just one gene, or a set of related genes called a gene panel. But two broader types of testing have become increasingly important: whole genome sequencing (WGS) and whole exome sequencing (WES).
- Whole exome sequencing (WES) reads all of the genes, or the protein-coding parts of your genome — the sections that directly tell your body how to make proteins. This covers about 1–2% of your total DNA, but it includes most of the genetic changes known to cause disease.
- Whole genome sequencing (WGS) reads your entire genome — all 3 billion letters, including both the coding regions and the non-coding sections that play important roles in regulating genes.
Both types of testing look at thousands of genes at one time, giving your medical team a much wider view than a standard gene panel can provide.
Why Would a Doctor Order Whole Genome or Exome Testing Instead of a Panel?
Great question. The answer often comes down to how clear the picture is.
If your symptoms strongly point to a specific condition or group of conditions, your doctor may start with a more targeted test — like a gene panel focused on the most likely possibilities. For example, if a child shows signs of a well-recognized syndrome, it may make sense to test for that condition directly.
But when symptoms are unusual, affect multiple parts of the body, or haven’t led to a clear diagnosis after standard testing, a broader approach often makes more sense. Whole exome or genome sequencing can look at thousands of genes at once — casting a much wider net without requiring multiple separate tests.
This broader approach can shorten the time to diagnosis, reduce the number of tests a person needs, and lower overall health care costs. Research has found that WES or WGS can be more cost-effective when ordered early in the diagnostic process rather than as a last resort.
Because of this, clinical guidelines from organizations such as the American College of Medical Genetics and Genomics (ACMG) now recommend considering whole exome or genome sequencing as a first-line diagnostic test for many patients — particularly children with congenital anomalies, unexplained developmental delay, or intellectual disability. Insurance coverage for these tests has also grown significantly in recent years, with many major insurers now covering WES and WGS when specific clinical criteria are met.
Who May Especially Benefit From Whole Genome or Exome Testing?
While this type of testing isn’t right for everyone, it can be especially valuable for people who:
- Have symptoms affecting multiple organ systems that don’t fit a clear diagnosis
- Have been through extensive testing without getting answers
- Have a condition suspected to have a genetic cause, but no specific diagnosis has been found
- Have a rare disease, or may have a rare disease
- Have a family history of an undiagnosed condition
- Are children with unexplained developmental delays, intellectual disability, or birth differences
About 80% of rare diseases have a genetic origin, yet the journey to a correct diagnosis can take years or even decades. Whole genome and exome sequencing can be a powerful tool to shorten that journey.
What Are the Chances of Getting a Diagnosis?
It’s natural to wonder: if I do this testing, will I actually get a diagnosis?
The honest answer is: it depends on your situation. Overall, studies show that whole exome and genome sequencing leads to a diagnosis in roughly 30–40% of people with rare or undiagnosed conditions. That number may be higher in children and in people who haven’t had prior genetic testing.
While those odds mean that testing doesn’t provide an answer for everyone, a 30–40% diagnostic rate is significantly higher than what traditional gene panels or single-gene tests have historically offered — especially for complex or unexplained conditions.
Even when testing doesn’t return a clear diagnosis, it can still be valuable. Results can rule out certain conditions, inform family planning, and may be re-analyzed in the future as new genes and diseases are discovered.
How Can a Genetic Diagnosis Change Your Care?
Getting a genetic diagnosis isn’t just about putting a name to a condition. For many people, it can open doors that weren’t available before. A diagnosis can:
- Guide treatment decisions — some conditions have specific treatments or therapies that work best when the underlying genetic cause is known
- Help avoid harmful treatments — knowing a genetic cause can sometimes prevent treatments that wouldn’t work or could cause harm
- Connect you to specialists and resources — a diagnosis can link you to disease-specific specialists, support groups, and clinical trials
- Inform family members — understanding a genetic cause can help relatives make informed decisions about their own health
- End the diagnostic odyssey — for many patients and families, simply having an answer brings emotional relief and a clearer path forward
It’s important to understand that a genetic diagnosis is not the same as a treatment in itself. And while some conditions with a genetic cause do have genetically targeted therapies — treatments designed to work based on a specific genetic change — not all do. A genetic specialist can explain what your specific results mean and what options are available to you.
The Role of a Genetic Counselor or Medical Geneticist
Whole genome and exome test results are complex. A single test can identify multiple genetic variants, and figuring out which ones are meaningful takes expert knowledge. This is where genetic counselors and medical geneticists play a critical role.
These specialists are trained to:
- Review your personal and family medical history
- Explain what your test results mean in plain language
- Help you understand the difference between a clearly disease-causing change versus a “variant of uncertain significance” (a change whose meaning isn’t yet clear)
- Help guide next steps
The American College of Medical Genetics and Genomics (ACMG) recommends that genetic counseling be provided both before and after whole genome or exome testing. Having this guidance makes a significant difference in how useful your results are.
At Genome Medical, our team of genetic counselors and medical geneticists can support you through the entire process — from deciding whether this type of testing is right for you, ordering testing when appropriate, and helping you understand your results and what they mean for your care.
The Bottom Line
Your genome is the complete set of instructions that makes you, you. When something in those instructions contributes to a health condition, whole genome or exome sequencing can often help find the cause — especially when other testing hasn’t provided answers. While this type of testing doesn’t always return a diagnosis, it offers one of the best chances available today at finding answers for people with rare or undiagnosed conditions.
With the right support from a genetic counselor or medical geneticist, understanding your genome can be a powerful step toward better, more personalized care.
Have questions about genetic testing? Schedule an appointment to meet with one of our genetic counselors.
