Genetic Testing; What’s It All About?
Genetic testing is a booming industry. Thanks to innovations in the biotechnology space, there are more ways than ever for a person to understand their genetic lineage through genetic testing. It can be used to tackle diseases like cancer, Alzheimer's, and other neurological diseases, as well as determining what the best diet or exercise routine is the most optimal based on our individual genetic history. Companies like AirBnB are even promoting genetic testing alongside their own services to maximize the experiences of their customers. But what exactly IS genetic testing, and how does it work?
The Human Genome Project
Let’s start with some basic biology. Every organism has a genome, which is the complete set of a living organism’s DNA. DNA is a chemical compound containing genetic information and instructions to direct activities within an organism. Our genome, the human genome, has over 3.2 billion base pairs of DNA which contain ALL of the biological instructions for human growth, development, and function. In 1990 scientists from all over the globe collaborated with the goal of mapping the human genome, calling the sum of their efforts the Human Genome Project. Using the DNA of several anonymous volunteers, scientists went through the slow, pain-staking process of sequencing their DNA with the end goal of having a complete blueprint of the human genome. Despite $3 billion in funding ($5 billion adjusted for today’s inflation) and the involvement of 16 genomic centers around the globe, the Human Genome Project took over a decade to complete. In 2003, scientists were finally able to “complete” the human genome sequence (less than 1% of the sequence to this day remains incomplete), declaring the project finished. The incredible insight gained from the results of the Human Genome Project is the basis of the many genetic testing products and services available to us today.
The first direct to consumer tests became available years after the completion of the project but costed in the hundreds of thousands of dollars to get your hands on. Nowadays, thanks to innovations in the field of biotechnology, genetic testing kits can cost less than $200.
The Different Types of Genetic Testing
Genetic testing can be performed using two different methods. The first method is called “genotyping.” Humans have 99.9% of their DNA in common, but the remaining 0.1% is what makes every human different or unique. This is where genotyping comes in, as genotyping focuses on sequencing the small portion of DNA that makes every human different. The second method is called “sequencing.” Sequencing focuses on every single sequence of a person’s genome, yielding a more complete genetic picture. The results of sequencing are meticulous and can give much clearer answers to a person seeking out their likelihood of developing certain diseases. Generally speaking, a person purchases a genetic test for two reasons; they want to either perform an ancestry test, or a health test.
Ancestry Tests
Companies like Ancestry and 23 & Me use genotyping to take a look at a person’s genetic variance in order to determine their lineage. After receiving your DNA, usually in the form of a bodily fluid like saliva, they compare your results with reference populations already stored in their database. This database is comprised of many millions of people who have already submitted DNA to the company. The results you receive back from the company however are not really a look into your family’s past, but rather how strong a few unique genetic markers resemble different modern populations around the world who have also submitted their DNA for sequencing. The trace percentages of ancestry from lands far from where a person was actually born are valid only within a margin of error, not conclusive. For example, when a person takes an ancestry test and receives a result that suggests they are “1% Irish” or “1.5% Native American”, this result is not conclusive.
Health Tests
While ancestry tests can tell us about our past, genetic health tests can give us a glimpse into our future. A person who desires to determine their risk for health complications like diabetes, obesity, and others can do so with these tests. Companies like myDNA and Atlas Biomed perform health tests using both genotyping and full genome sequencing. DNA collection for health tests is similar to ancestry tests, with a person sending their DNA in the form of some kind of bodily fluid (saliva, blood, etc.) to a lab for testing.
Results
The results of performing genetic testing of any kind usually take at minimum a few weeks. These results will vary from person to person, because every human being is different. More in-depth tests will yield more in-depth results, such as having a full genome sequencing test performed. These results are not always easy to understand, especially if you do not possess the required medical background to interpret them. This is where genetic counseling comes in.
Genetic Counseling
Suppose a couple has a small child who was diagnosed with a rare but debilitating auto-immune disease. If they wanted to have another child, it would be in their best interest to determine the genetic risk of their next child also developing the auto-immune disease. They take a genetic health test, but aren’t quite sure how to interpret the results. This is where they could use the expertise of a genetic counselor. Genetic counselors are medical professionals who have the ability to understand and interpret the results of a person’s genetic test, providing much needed medical context to evaluate a given situation. They take the time to look through a person’s medical and familial history in order to draw certain conclusions and devise a plan of action based on that history. Genetic counselors also provide emotional support, and can also determine if any additional tests are necessary based on genetic testing results.
The Future of Genetic Testing
Although we have had many advancements in our understanding of our DNA since the completion of the Human Genome Project, we are still very much in the early stages of what is possible when it comes to gene sequencing. Genome sequencing is getting faster and faster, and with advancements in the field of biotechnology, there may soon be a time when genetic testing costs no more than a lotto ticket. Genomic sequencing may also one day be an integral part of routine medical diagnostics, which can lead to disease prevention at a rate much faster than anything we have ever seen.