I am one of those people who has my personal genome at my fingertips.
Almost two years ago, after seeing a geneticist regarding a possible Ehlers-Danlos Syndrome diagnosis (a diagnosis I did not receive), I decided to pay to have access to my own genetic sequence data. My genetics appointment left me feeling like I just wanted more information about myself. I didn’t want to have to wait for a specialist to feel strongly enough about something to warrant the genetic testing.
23andMe, a company you may have heard of, operates in the United States of America. Last year I believe it was just $200 to order a DNA kit. As of today’s date (2017-01-23) it’s $249 CAD. The kit arrives, you spit a lot into a plastic tube and you send it back off. Not long after, you received your genetic information online from 23andMe.
After the information arrives, you quickly realize it’s A LOT of information! 23andMe provides some reports split into larger categories of “Health” and “Ancestry”. If however, you’d like to explore more, you can choose to sign up with a number of different third party companies that have filled the hole in the market for helping shift through your data. I’m signed up with LiveWello.com for instance. For $20 I was able to upload my 23andMe data to LiveWello then from LiveWello I could create my own variance reports… Ok, I think I might have lost most of you so I will back up. 🙂
We have genetic information that is the essence of who we are stored on 23 pairs of chromosomes. Generally speaking, half of our genetic information comes from each biological parent. Our DNA strands are wounded up tightly (like a long long string or rubber band that you keep winding and it folds in on itself) and contain pairs of nucleotides with a base pair lock-and-key type markers that connect to each other to form the “rungs” of the DNA “ladder”. There are only four base pairs. Adenine (A) links with thymine (T) whereas cytosine (C) links with guanine (G). The sequence of these simple linkages makes up who we are genetically speaking. So simple. So complex. So mind-boggling!
A gene is a grouping of nucleotide base pairs that form a functional unit. For instance, one of the major genes involved in eye colour expression is the OCA2 gene, which provides a map to creating a the P protein, a protein found in melanocytes (cells that create melanin – a substance which gives skin, hair and eyes colouring). The OCA2 gene is located between base pairs 27,719,008 to 28,099,342 on chromosome 15 (citation). *Time to pause in wonder at DNA and life and patterns and disorder… WOW!*
Humans have 23 chromosome pairs. The two sets of genetic information on these chromosomes don’t necessarily match. It’s part of the magic of individuality even at the DNA base pair level of each and every one of us. The word used when looking at genes and their differences is “allele”. “Allele” just means gene variance. There are alleles that are “dominant” or “recessive” and these result in different outward expression (or phenotype) of certain genes.
Ok, enough details and definitions for now… let’s look at a concrete example. Above is my 23andMe “chromosome view” of ancestry. You can see my 23 pairs of chromosomes lined up. My info may be easier to distinguish than others because I am half Thai (of Chinese decent) and half French-Canadian (of European descent). For my chromosome 15 you can see that one set is clearly large portion British-Irish (from one parent) and the other is mostly Chinese ancestry (from the other parent). Wherever the exact OCA2 gene is, I have one dominant (dark eye colour) allele from one parent and the second recessive (light eye colour) allele from the other. My phenotype (what shows as my eye colour) is the dominant dark eye colour. My genotype (what is coded but not necessarily seen) is heterogygous (meaning one dominant allele and one recessive allele). Of course it’s much more complicated, but it gives you a bit of an idea.
Once the human genome was map, researchers dived right in. If, as a researcher, you were interested in finding whether there was a genetic basis for acrophobia (the fear of crowds) for instance, you would recruit a population (for good scientific results, the more people the better) who were afraid of crowds and see whether you could find some common variance in their alleles. You would compare against an equally large (or larger) group of normal “controls” (people who aren’t afraid of crowds) and calculate with how much certainty / confidence you can report any associations and possible risk alleles. I did not do well when I studied statistics so I will stop at that.
Just for fun, the National Post newspaper publish an article in 2013 based on findings in a particular study on phobias. The news article by Rebecca Tucker was titled “Afraid of heights? Blame your parents: New study suggests phobia may be genetic“.
So once I had my genome at my fingertips I could figure everything out myself, right? Wrong! Sure one can sift through scholarly articles and reviews to find risk alleles, but even knowing what those are and being able to compare them to individual data doesn’t necessarily lead to something significant. There are some diseases where it is know exactly which one based pair is responsible for disease expression, but for things like Ehlers-Dandlos Syndrome or auto-immune conditions, it is much more complicated. On top of that, even IF a person where to have all the risk alleles present, it would only represent a part of what would constitute the systemic disease entity. The rest of the picture would include environmental factors (trauma/stress etc.)
Having my own genome mapped has allowed me to truly marvel at the complexity of my body. It has not given me any more answers but can often lead to more questions. As someone with curiosity, playing about with my own data and skimming articles is something I dive into occasionally, but I understand now that, for me, it is not very likely to lead to anything definitive.
Where having mapped genomes of larger patient populations does help is in research, as mentioned above. If a large group of a certain population of people is found (e.g. Chinese people with a lupus diagnosis), then researchers can look at their DNA in great detail to try and find patterns. If links can be made or patterns found, whatever aspect of the body or disease they were looking at could perhaps be better understood. In many cases, the exact location(s) of genes and gene mutations from whence disease originates is not known. Finding risk alleles helps lead research into treatment and cures for diseases. As a researcher into complex systemic human disease, it must be nice to have any clues, no matter how small!
As far as diagnosis and using genetic information for diagnosing patients, I understand now that, for a large majority of conditions, genetic reports would mean very little. A clinician would still have to diagnose based on signs and symptoms combined with diagnostic testing and lab results (unless one were dealing with a disease where a specific known base pair(s) was the problem).
In conclusion, in my personal case, though I do not regret paying for my genome, it has not led to much (besides many “lost” hours of exploring, helping to fulfill my curiosity and increasing my learning). 🙂
Do you have your own genome sequenced? Have you enjoyed diving into the genome “rabbit hole”?
Note: The issue of genetic information and privacy is a hot topic. I will not delve into it here but you can bet I read the terms and conditions for 23andMe and LiveWello very carefully before going forward!