If you’ve ever lied about your height on a dating app, we now know to whom you can address your grievances. No, not any reinforced societal expectations about what heterosexual relationships look like or how traditional masculinity or femininity manifests, but a stretch of genetic variations.
Height is one of the easiest physical characteristics to measure, and we know that it’s a trait with high hereditability, meaning inherited genes almost entirely determine it. This trait seems like it should be a fairly straightforward one to parse genetically, but the actual places where gene variations occur have been hard to pin down.
Researchers in Australia, the U.K., and the U.S. published a study on Wednesday in the journal Nature that provides evidence for more than 12,000 spots in the human genome that are associated with height.
What’s new — In the largest and most diverse genome-wide association study (GWAS) to date, the study’s authors have identified 12,111 places in the human genome associated with height. The team analyzed existing genetic data from nearly 5.4 million people, more than a million of whom were not of European ancestry.
Throughout one’s DNA are single nucleotide polymorphisms (SNP, pronounced “snip”), which are spots for genetic variation. SNPs are, in part, what’s responsible for eye and hair color, height variation, and pretty much any other inherited trait. These aren’t mutations but spots where a particular nucleotide (adenine, cytosine, guanine, and thymine) exists. These nucleotides encode certain traits.
This study has pinpointed more than 12,000 locations in the human genome where those SNPs coding for height occur.
Why it matters — As simple as height may seem, there’s so much we still don’t know about it.
Loic Yengo, lead author, and statistical geneticist at the University of Queensland, says this work sets the stage for future genetic investigation of other traits and diseases, demonstrating that genetic data alone can contribute a significant portion of trait variation and risk of disease.
It also offers a guide on sample sizes. Though this is the largest GWAS to date, it will likely impel broader and broader studies with even more people.
Widening the sample size is important for the future of personalized medicine, Yengo wrote in an email to Inverse. The more genetic material included, the better researchers will get at identifying at-risk patients before an inherited disease or trait progresses beyond prevention.
“More directly, this study teaches something about the biology of bone growth and can eventually help us design treatments for certain skeletal growth disorders,” Yengo wrote to Inverse.
Digging into the details — Genetic information on European ancestry is now saturated. There aren’t many more unknown common variants associated with height in this population. According to Yengo, these more than 12,000 genetic variants account for about 40 percent of height variation in European ancestry.
“We’ve more or less finished mapping them, at least for European ancestry,” Joel Hirschhorn, senior author, and a pediatric endocrinologist at Boston Children’s Hospital tells Inverse. Genetic rarities, however, still remain. Yengo now wants to focus on rare variants present in less than 1 percent of that population.
And, there are plenty of other ancestry groups that must be investigated for common variants. In this study, fewer than 78,000 people represented South Asian ancestry. But Hirschhorn and Yengo point to the importance of better understanding height in African ancestries.
“Ancestries with an ‘s’ because of the large diversity existing on the African continent,” Yengo writes. Considering human life originated in Africa, information from these populations could provide novel insights.
“Humans all started as one relatively small group in Africa,” Hirschhorn says. “Some of that genetic diversity left Africa, and some of it stayed behind.” Since these genes come from much older populations, it has more genetic variability because it’s had so much more time to evolve.
“There’s more to discover and better ability to pinpoint where the right variants are, but to do that, you need large studies of folks with African ancestry,” he says.”
What’s next — These analyses will only get bigger and more diverse. Yengo’s vision for this research’s future is to home in on rarer genetic variants that alter height and to find even more height variants in other populations.
Hirschhorn’s interested in the immediate biological understanding we can glean. The more relevant genes we understand, the better we can get to know the biological mechanisms behind how height and skeletal growth work. He also says this study offers an opportunity for prevention and intervention when it comes to genetic disorders or diseases that affect height.
“And as a pediatric endocrinologist, I see a lot of kids where the parents come in because they’re concerned about their child growing too slowly,” he says. As sci-fi as it may seem, it’s not too hard to look at that kid’s genetics to see if perhaps they’re going to end up on the shorter side based on variants identified. But if that kid’s genetics suggest they should end up on the taller side, then there may be something else going on worth investigating.
Nobody needs genetic testing to at least partially, if not mostly, understand their own height. If you’re curious, see if you can learn your parents’ heights, and that should offer some insight.