Moment of Inertia, Issue #3 | What a Tangled Web We Weave

Yesterday's M&D featured an article about research identifying key gene locations that play a role in determining the physical characteristics we associate with beauty. Genetics is rarely that simple in actuality, though.


What a Tangled Web We Weave

Long the exclusive domain of science fiction, the genetic modification of human beings is quickly (perhaps too quickly) becoming a reality. New tools like CRISPR and whole-genome sequencing are quickly making a future where we can play god with the living world look plausible.

The taste of genetics education (in the form of Punnet squares and pedigree charts, usually) we may receive in high school, however, paints a simpler picture of genetics than is often the case. Rarely is it the case that one gene, and only one gene, controls a feature like height, hair color, or eye color. Furthermore, these physical variants are rarely encoded as either one version of said gene or another (i.e., dominant and recessive traits). No, more often than not, human genetics (and indeed genetics writ large) is the story of a complex interplay between genes, each of which makes up a facet of a broader phenotypical picture.

Indeed, just as we can't understand an entire story based on the individual words that make it up, we can't understand our genetic code until we see how all the genes interact with each other. The "beauty genes" article makes this clear too: you can't just "turn up" the genes that control physical appearance without also affecting other aspects of health. For females these genes appeared to be tied to genes affecting body mass, and in men the genes seem to be linked to cholesterol levels. Much like an elaborate web, you can't pull on one thread without also at least jostling a few others.

So changing our genetics and our progeny's genetics isn't as simple as crossing pea plants with different leaf colors (@Gregor Mendel). That doesn't mean its impossible to make alterations to our genetics, just more complicated. To effectively (and ethically) make changes to the human genome, we need to have a deep understanding of the interconnectedness of our genes - and we are well on our way.

While we are beginning to build a library of the human genome (a functional library, not only the list of genes we compiled at the end of the Human Genome Project), we're not filling in all entries equally. As the article from M&D states, only people of European ancestry were involved in the beauty genes study. Although humans are over 99% genetically identical, the key variants that make us unique are just that: key. These variants don't only manifest in the form of traits like skin color, they can also manifest in the form of diseases and chronic conditions that are more prevalent in some ethnicities and races than others. As such, building a map of only one subset of all human races/ethnicities gives us a limited picture of all the different ways our genes may interact with one another.

As it stands right now, we've got a decent picture of the genomes of people of European ancestry, but are lacking on pretty much all other fronts. One way this imbalance can be addressed is by increasing the participation of non-Europeans in the studies and clinical trials that gather human genetic data. Traditionally, the US hasn't done the best job when it comes to running clinical trials with people of color, to put it (very) mildly, so it's understandable that the very communities from which we need to be gathering more medical data are the most leery of participating in clinical trials. Things are much better than they once were, though, and organizations like the All of Us research program from the NIH are setting up new systems that are empowering expanded participation in research studies so that in the future we can work with the data we're sorely in need of right now and beginning reading the entire story of the human genome.