Whole Genome Sequencing

Whole genome sequencing is different than gene sequencing. It is also different from whole exome sequencing which only looks at a person’s exons, the parts of DNA that code for proteins in the body. Researchers like this method because it is faster and cheaper.

More still needs to be done before whole genome sequencing becomes a routine part of medical care.  Many questions remain for researchers, health professionals, and policymakers.  Read about some of the barriers and questions that still exist by clicking here .

Your genes don’t determine everything.  They can tell you that you are at a higher risk of disease, but the personal choices you make and the environment in which you live still play a very important role.  It is important to maintain a healthy lifestyle in order to minimize your risk of disease.  The growing field of gene-environment research focuses on how your lifestyle and environment interact with your genes to affect your health.

The Story of Nic Volker

Whole genome sequencing is becoming a new way to diagnose diseases or disorders that were undiagnosed using traditional tests.  One miraculous example of this is the story of Nic Volker.  Nic was a 6-year-old with a mysterious disease that caused many misdiagnoses and ineffective treatments.  Eventually, researchers at the Medical College of Wisconsin used whole genome sequencing and diagnosed a rare genetic disease.  This discovery is what saved his life.  For the full story, click here.

What is whole genome sequencing?

Whole genome sequencing is the mapping out of a person’s unique DNA. Your genome is the unique blueprint for your body. Sometimes, because of new or inherited genetic mutations, your genes can cause a disease or increase your risk for disease. By sequencing your genome, health professionals can look at the unique variations found in your genes. Some of it matters.  Some doesn’t matter.  Some is still unknown or uncertain.

It is most often used in medical research and is beginning to be used more in clinical practice. For example, a doctor or genetic counselor could use whole genome sequencing to see if a patient has a genetic disorder or is at risk for a disease.  

Whole genome sequencing results can be placed into 3 categories: Single-gene disorders, multi-factorial disorders, and the pharmacogenomic profile.

  1. Single-gene disorders (sometimes also called Mendelian disorders) are diseases that are caused by a mutation in the DNA for one gene. An example of these diseases is Sickle Cell Anemia.
  2. Multi-factorial disorders are diseases associated with DNA changes in more than one gene. This often includes diseases like obesity and diabetes and often is highly influenced by your environment.
  3. Pharmacogenomic profiles use an individual's genetic code to determine how they will respond to a drug so that a doctor can prescribe the correct amount. This is an example of personalized medicine.

How can I be tested?

Today, whole genome sequencing is mainly used in research, but there are several companies that can sequence your DNA.  These are known as direct-to-consumer tests.  The testing that is offered through a physician is currently several thousand dollars.  Many biotechnology companies, however, are racing to sequence the genome for under $1000 and at a faster rate.

If you do choose to have your whole genome sequenced, it is very important and helpful to review your results with a trained professional. Also, you should make sure the lab is CLIA certified.

What do the test results mean?

Whole genome sequencing is not your average diagnostic test.  A blood pressure test will give you a straightforward ‘yes’ or ‘no’ answer about your health.  Whole genome sequencing, though, will often give you a ‘maybe.’  Most of the information you get from a genomic test tells you about your risk for disease, not whether you have a disease or will for sure get the disease.

A health forecast: Understanding disease risk from whole genomic sequencing

Weather forecasting tries to predict what the weather will be like in an hour, a day, or a week.  It involves knowledge of patterns and statistics.  When a weather forecast predicts rain this coming weekend, it usually comes as a percentage, like 30% chance of showers. We then take that information and prepare for it by changing our plans or carrying an umbrella with us.

Whole genome sequencing is a lot like weather forecasting. It doesn’t predict exactly what will happen, but gives you the chances of something happening. This means that it will tell you more about your risk for a certain disease, like diabetes, not if you have diabetes or not. But just because genomic information is often uncertain doesn’t make it less useful. We can take that information and change our lifestyle choices to better our health.

Questions to consider

Whole genome sequencing may not be right for everyone, so it is important to ask yourself whether you think it is right for you.  Some may not want to know about their genetic risks whereas other people want to know everything about their genome.  Here are some questions to think about if you are considering whole genome sequencing:

  • Am I concerned about the privacy of my results?
  • Who would I want to share my results with?  How would I feel about sharing them with my employer or insurance company?
  • How old should a person be before he or she can get tested?
  • What will my results mean for my family members who may share a similar genetic makeup?
  • Is there any information about disease risk that I would not want to know?
  • Do I want to know about something that may not affect me in the next 10 or more years?
  • Do I want to know about a genetic disease for which there is no treatment?
  • How do I feel about receiving uncertain results, or results that tell me ‘maybe’ rather than ‘yes’ or ‘no’?
  • What is my family history?  Am I prepared to receive news that is unexpected?
  • What would this information mean for my health?  What sorts of actions would I take?

Because the results of a genomic test are complicated and include a large amount of information, it is best to meet with a genetic counselor or trained health professional to explain your results and answer any questions or concerns you might have.