Last Christmas, my (maternal) grandparents received an unusual present—they had their genomes sequenced! Well, not their entire genomes (because that would cost about $1,000 USD) but part of their genomes. For 1/10th the cost, they each had about 602,000 of their 10 million SNPs sequenced. SNPs or Single Nucleotide Polymorphisms are places in a person’s genome where one of the nucleotides (A, G, C or T) can be substituted for another; a source of genetic variation that occurs in more than 1% of the population. (This site has a good SNPs figure.) SNPs occur about once every 300 nucleotides and can be in the DNA sequences between genes, acting as biological markers for nearby disease related genes, or within genes where they can directly affect gene expression. Most SNPs do not affect health but some do, affecting responses to certain drugs, susceptibility to toxins and other environmental factors, and the risk of developing certain diseases.
The Human Genome
Image owned by Wikimedia Commons (CC0 Public Domain)
So, after Gramma and Opa sent their saliva samples, the DNA sequencing company analyzed their SNPs, emailed them to let them know they could access their results online, and we got to take a look at what the sequencing had uncovered. 23andMe provided a lot of data—the raw results and analyses on their risks of having various inherited conditions, genetic risk factors, possible responses to certain medications, and traits.
Before presenting the results of the genetic risk factors and inherited conditions, the company carefully stated that the results should be discussed with your doctor and to realize that this doesn’t necessarily mean you will or will not develop a specific condition since there are other genetic variants linked to these conditions that weren’t tested for. The company also pointed out that environmental and lifestyle factors can contribute to these diseases. Before being able to see the results, Opa and Gramma had to read a legal document and click that they understood. Only then, could they see the results. However, Opa and Gramma are lucky, they’re Canadian so they actually have access to the health analyses; people in the US do not. Americans can only see the results of the ancestry analyses at the moment because the FDA (Food and Drug Administration) has classified 23andMe’s DNA sequencing test as an unapproved medical device).
My Grandmother’s Ancestry
Among the inherited conditions where the company reported whether the variant was present or absent included sickle cell anemia, cystic fibrosis, phenylketonuria and Tay-Sachs Disease while among the genetic risk factors, variants were reported as present or absent for celiac disease, Alzheimer’s disease, Parkinson’s Disease and breast cancer (BRCA1 and 2) along with others. Since Opa and Gramma both know what diseases run in their families, the results from these two analyses didn’t come as any surprise. However, the drug response analyses were unexpected and potentially life-saving. It turns out one of my grandparents has a predicted increased sensitivity to one family of drugs and the other has a higher than normal risk of myopathy if they take statins. These are useful pieces of information that they can tell their doctors if medications need to be prescribed.
Another analysis done on my grandparents’ DNA was ancestry composition. Here’s a screen grab of my grandmother’s ancestral analysis: The analysis showed what percentage of her DNA came from each of the world’s 31 populations. In her case, she is 99.3% European, 0.4% East Asian and native American, 0.1% Middle Eastern and North African, 0.1% subSaharan and 0.1% unassigned. She also has 2.5% Neanderthal DNA! [The average is between 1-4%.] This information isn’t very useful but it is interesting and shows how interconnected the human race is.
So, did my grandparents find having (some of) their genome sequenced worth it? Yes. Did it provide some useful information? Yes. Will I be getting mine done at some point? Definitely!