It comes as a shock to many of my colleagues (and friends, but somehow not my family) that I am an avid viewer of Keeping up with the Kardashians (#KUWTK). And for every 8 episodes full of micro-dramas, naked photo shoots, and cray cray family dynamics, they’ll actually touch on some weighty issues. Last Sunday’s episode (season 11-episode 9) was one of those episodes as they discussed the pros and cons of genetic testing and personalized medicine.
Personalized medicine is a touch outside the scope of our themes at WildlifeSNPits as we focus on the intersection of conservation and evolution. As our readers know we take a genetics/genomics heavy view of evolution; in this way the Kardashians’ discussion of genomic testing was right up our alley. One thing we see in wildlife genetics is that the techniques developed for humans trickle down to us in time. Thus it’s not too unrealistic to think in the future we could have panels of genomic markers associated with disease in wildlife and use those to monitor health of natural or captive populations.
In case you were not watching #KUWTK with me, here’s what you missed: Kris Jenner (the matriarch) has a family history of breast and cervical cancer*. She arranges for herself and her daughters to have a genetic test for markers associated with cancer. The daughters agree (except for Khloe who gets her arm twisted into it), they have blood drawn, then they receive their genome reports in a dramatically edited meeting.
Some diseases have a genetic component (G), others an environmental component (E), and others still have both a genetic and an environmental component (G x E). #KUWTK only focused on the genetic component so I will too. There are genes that are associated with cancer susceptibility. If we take several thousand people, some with breast cancer and some without, and we look at hundreds of thousands of SNPs (genetic markers) in everyone’s genome, we can do an analysis called Genome Wide Association Studies (GWAS) to find genetic variants that are statistically associated with breast cancer. For most genetic markers there will be no difference if people with cancer have one variant or the other; but for markers associated with cancer, people with cancer will have one variant at a much higher proportion than people without cancer. This is one way in which genomics are being used to identify variants associated with all kinds of diseases.
It’s like the same thing that Angelina Jolie did where she had an 80% chance of cancer so she got her boobs removed.
What the Kardashians Got Wrong about Genetics
Several times during the episode someone would refer to the genetic test as a way to look for, “the genes for cancer.” The test doesn’t look for the genes for cancer it looks for the variants (or alleles) associated with cancer risk. It may seem like semantics but understanding the difference between genes and alleles is a major concept in genetics especially as applied to personalized medicine.
The truth is all of the Kardashians have the BRAC1 and BRAC2 genes. So do I. So do you. But genetic tests identify which allele of each gene you have. Since you have one copy of each gene from each of your parents, the possible genotypes, at BRAC1 for example are:
Not Susceptible/Not Susceptible
This is a simplified version. There are more than two alleles because any of the base pairs in the gene can mutate; however, not all are associated with an increased risk of cancer. (Of note, the susceptible alleles are very low in the population.)
What the Kardashians Got Right about Genetics
After the women receive their genetic test results, Kim asks, “is [this] the current situation,” in reference to the ability for genes to mutate over time. The doctors explained that the genome is set since birth, the alleles genotyped during this test will be the same alleles that a person has always had and will have in the future. This relates to our recent discussion of the difference between genomics (the sequence of each individual’s DNA) and transcriptomics (the expression of your genes). The genome doesn’t change, but the transcriptome changes between tissues, and can also change in response to the environment (ex- heat or stress).
During the episode, Kris said it’s a privilege to have a genetic test. Actually, there are a lot of companies that would be happy to take your money for a test. Many people do not need one, but it’s not something that is only available to the super wealthy. I’ve had one (mostly to find out ancestral history), and trust me I’m not in the same income bracket as the beauties on TV.
*- A commenter pointed out that there is not a DNA test for susceptibility to cervical cancer.