What About Those Asthma Genes?
Last summer, I did an Ancestry DNA test. It didn’t tell me anything the least bit shocking—I am, as I like to say, “very white”, with the majority of my ethnicity estimate comprised of 51% England, Wales & Northwestern Europe, 20% Scotland, 19% Eastern European & Russia—my under 10% amounts were also unsurprising, save perhaps for the inclusion of 2% Sweden. I didn’t think I’d learn a ton from doing this test, but it sure was fun waiting for the results!
Then, a few weeks ago, I began contemplating the genetics of heritable diseases. And became curious. A lot of people have no interest in knowing their disease risks for the future, but I am not one of those people. My curiosity can go from “Huh, I wonder” to insatiable in about 27 seconds. I re-found this website called Promethease, did some quick Googling for a reasonable assurance of security, paid $12 USD and uploaded my raw DNA file to get some sweet data.
The genetics of asthma
It is clear that asthma can be passed down through genetics in families, but the pattern of inheritance is unknown.1 According to the National Institutes of Health (NIH), certain gene mutations carry the risk of developing asthma, not the condition itself.1 This is due to the fact that it appears a person must have both asthma genes and the ‘perfect storm’ of environmental factors to actually develop asthma.1 You can develop asthma without asthma genes, but you can also have asthma genes without ever developing asthma.2
Does my DNA tell me why I got asthma?
The first thing to consider here is that I presume we are nowhere close to isolating all of the asthma genes that exist. According to Promethease, there are 47 genes—more accurately, single nucleotide polymorphisms (SNPs), which are most simply variations within or between genes3—in their database for asthma. The NIH states there are more than 100 genes that may be associated with asthma.1. A gene will be named something like rs2305480 followed by two letters, ie. (C;T), and those bracketed letters contain the SNP.
Some of the genes or SNPs in Promethease note the risk being increased for people of certain ethnicities with the gene. Given the little we know about genes and asthma, I cannot deduce whether or not this means the information only applies to them, or that the study was done on participants of this ethnic population, thus why the ethnicity was notable.
Here are my “bad” repute asthma genes and SNPs from Promethease:
rs2305480(C;T): “3.5x increase in risk of asthma for Han Chinese” for the C;T SNP. (C;C is normal and T;T is associated with 3x greater risk of asthma under age 4 if exposed to smoke.) 4 Okay, except I’m not Chinese, depending on how or if this makes a difference. Next gene…
rs13153971(C;T): “Normal (higher) risk of Asthma. This is normal for white people.” (AKA me.)
Except then I kept reading, “But this (C;T) has 1.58x the risk compared to T;T (normal for non-white people).”5 However, this was apparently tested in Koreans5, so I still don’t fully understand. (What else is new?)
rs1361600(G;G): “~2x increased risk for adult-onset asthma in Japanese populations.” As opposed to genotype A;A, there is a 2 times increased risk for adult onset asthma—to which I posed to John “What If I already have (technically) childhood onset asthma?”
Too late for you, asthma gene—way ahead of you.
Similarly, I also have some “good” genes that would be protective against asthma—except clearly, those didn’t work. One even says I have a 0.84x decreased risk for late-onset asthma. Another claims “Half the risk (maybe) of Asthma.”6 Emphasis on maybe? Otherwise, I have a host of genes potentially related to asthma but which are normal “normal” or “common in complete genomics”.
Does my asthma have to do with my genetics?
Well, maybe. After all, isolating a gene’s potential to trigger a disease state make it clear that asthma can be passed down in families—my grandma has adult-onset asthma, and my great-grandfather had asthma. However, we’re the only ones. Even though my asthma didn’t onset until I was 16, I still believe there is a greater chance that, just due to how my asthma acts, may be linked to a greater extent to my prematurity than my genetics. However, there are probably still 65+ asthma genes Promethease isn’t yet telling me about!
Putting aside ethical or potential privacy issues (for now), have you considered doing DNA testing for future medical problems (or to demystify current ones)? How did you decide?
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