Interpreting Your Personal Genetic Data
Lauren V. Alteio | October 15th, 2017
In 2001, the first human genome was sequenced in its entirety for the hefty price of $100 million [1]! Over a decade later, we can now sequence the complete human genome for around $1000, providing insights into all of the genes that make up the human body [1]. Although most people are still not likely to drop $1K to have all of their genes sequenced, there are many companies that sell kits for sequencing a subset of these genes for a fraction of the cost of sequencing an entire genome. But what does this process entail and what information can you get from having your genes sequenced?
Fig. 1. The cost of gene sequencing as decreased from $1 million to $1,000 over the last decade. Source.
Numerous companies are offering direct-to-consumer genetic testing, including 23andMe, Ancestry, and National Geographic, just to name a few. These companies focus on sequencing Single Nucleotide Polymorphisms, or SNPs, in your DNA sequence. About 99% of your DNA is similar to every other person on Earth, but SNPs are the source of variation within our genes that make us all different [2]. SNPs are changes in single letters in the alphabet of your individual genetic code, which result in changes in the way the book of your DNA is read. By tracking these sites of variation through gene sequencing, you can learn more about yourself, your ancestry, and your connection to other people across the globe.
I was lucky enough to get my SNPs sequenced using one of these sequencing services. I received my sequencing kit in the mail, and deposited some saliva in the tube that the company provided. The saliva sample I sent out contained many of my cheek cells, each housing plenty of DNA for genetic sequencing. Once the company received my saliva sample, they performed all the behind-the-scenes work to get the DNA ready for sequencing. This involves breaking down the cell membranes from my cheek cells and extracting the DNA. After the time-consuming process of getting pure DNA from your cells, the prepared DNA is inserted into a sequencing machine, which outputs data containing each of the letters in the genetic code of my tiny cheek cells [3]. Preparation of the DNA must be done carefully as to avoid breaking down the DNA and introducing any contamination. The whole process from cheek cell collection to completed data takes about three months!
Fig 2 Gene sequencing is a time and labor intensive process! DNA must be extracted from cells before it can be put into the sequencing machine to obtain the A’s, T’s, G’s and C’s that make up your genetic code. Source: Lauren Alteio
A few months after I sent out my saliva sample, I was able to view my results online! Many of the companies that offer consumer gene sequencing have interfaces where you can view your own data, or share with other people from around the world. I received ancestry data based on my DNA, which allowed me to learn how much of my DNA came from ethnicities around the world and how much of my DNA came from Neanderthals, which are thought to have interbred with modern humans nearly 50000 years ago [4]. My family has known that we are mainly of European descent, specifically Italian. However, I was surprised to find Middle Eastern and East Asia DNA in my sequences as well! I also received some insights into my maternal haplogroup, which is a genetic link to my ancestral history, allowing me to trace my maternal line back through time. The maternal haplogroup can be determined by the DNA contained within your cells’ mitochondria, and because this mitochondrial DNA is inherited directly from your mother, it doesn’t change very often through mutation like other genes, making it possible to trace your maternal ancestry [5]. After openly sharing my DNA results on the web interface, I was even contacted by a relative who had been adopted and was in search of information on her biological mother. We were estimated to be third cousins as a result of our DNA. Of course, sharing your genetic sequence data is a personal choice that each person must make independently.
In addition to all this ancestry data, I received some insights into my health and wellness based on my DNA. This information ranged from whether I enjoyed the taste of cilantro, to what type of muscle fibers I most likely possess, to my risk for getting Parkinson’s disease. This information is determined using Genome-Wide Association Studies, which compare genomes and find connections between genes and the result of their expression [6]. Most companies that offer genetic testing face restrictions in the health information they can provide. Although interesting, it is important to remember that this health information is just a suggestion. Estimates of how likely you are to get a disease are based on statistical comparisons to a whole community of people. For example, if you receive a result stating an increased risk for cystic fibrosis from a 20% to 30% chance, you are not destined to develop or pass on the disease. In fact, your chances of developing the disease are still very low, but might be slightly elevated when we look at the entire population at large. Some diseases are affected by your lifestyle choices, and the information you gain by having your genes sequenced might aid you in a conversation with your doctor.
Fig 3 DNA in every cell of your body is comprised of A’s, C’s, G’s, and T’s, which hold information passed down from your ancestors. Source.
Now that I have this information about my ancestry and health, what does it all mean and what do I do with it? Many of the companies that provide gene sequencing services also provide online interfaces for customers to explore their data. Here you can browse through ancestry and health related information, and read more about what all of these traits mean. You can connect with people using genetic similarity, which might be a great starting point toward building ancestry trees. You can even understand why you might sneeze when exposed to sunlight, and why caffeine doesn’t affect you as much as other people. These are just some examples of genetic-based traits that you can explore!
Taking the first step to getting your genes sequenced is like opening a new book. You might discover a long-lost relative or learn that you contain genes from a different ethnicity than you expected, leading you to explore different cultures. Genotyping is a great way to find out more about yourself, your family, and your health. There is no shortage of information available about this technology! If you are interested in learning more about the science and ethical concerns involved in getting your own genes sequenced check out this video. Maybe you too will begin this exciting journey toward self-discovery!
References:
[1] Wetterstrand KA. “DNA Sequencing Costs: Data”. NHGRI Genome Sequencing Program (GSP). www.genome.gov/sequencingcostsdata
[2] J. Craig Ventner Institute. “Genome Variation”. Genome News Network. http://www.genomenewsnetwork.org/resources/whats_a_genome/Chp4_1.shtml
[3] Goode MR., Cehong, SY., Li, N., Ray, WC. And Bartlett, CW. (2014). Collection and Extraction of Saliva DNA for Next Generation Sequencing. Journal of Visualized Experiments. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4442313/
[4] Panko, B. “How Ancient Neanderthal DNA Still Influences Our Genes Today”. http://www.smithsonianmag.com/science-nature/how-ancient-neanderthal-dna-still-influences-our-genes-today-180962285/
[5] Scientific American. “How Do Researchers Trace Mitochondrial DNA Over Centuries?”. https://www.scientificamerican.com/article/how-do-researchers-trace/
[6] McBride, CM., Wade, CH., and Kaphingst, KA. (2010). Consumers’ View of Direct-to-Consumer Genetic Information. Annual Review of Genomics and Human Genetics.http://www.annualreviews.org/doi/full/10.1146/annurev-genom-082509-141604