Researchers have pinpointed 83 rare genetic variants that may directly affect a person’s height. These variants, described in a study published today in Nature, don’t occur very often, but some were found to be associated with height differences of up to two centimeters (0.78 inches).
Scientists have long known that the genes people inherit are instrumental in determining how tall or short they become. And experts have been hunting down these genes as far back as the 1800s. “We knew for most people that [height] was due to the combination of multiple genes,” Joel Hirschhorn, a genetics expert at MIT’s Broad Institute and one of the study’s lead researchers, tells The Verge. In recent years, up to 700 common genetic variants have been found to be associated with height.
Most of these variants are so-called non-coding variants, which affect the production and timing of the protein a gene encodes. This is opposed to another type of mutation called coding variants, which instead change a protein’s structure. For instance, a coding variant may cause a protein to have a different number of amino acids than usual. For this study, Hirschhorn and his team wanted to focus on coding variants, which are easier to understand. “We understand a lot less about how non-coding variation works, so it’s harder to go from non-coding variation to an understanding of biology,” says Hirschhorn.
The research team analyzed the DNA of more than 700,000 individuals across multiple countries. They checked for more than 200,000 known coding variants, and cross-checked the results with the person’s height. This allowed them to narrow down the 83 genetic variants that seemed to be influencing height in some way. To better understand the mechanics of these mutations, they focused on one variant called STC2. Through a long complicated process, this gene influences a substance that helps to stimulate the growth of cells. So when STC2’s activity is impaired, a person may be taller. Hirschhorn says their follow-up work will focus on the biology of all these variants.
A lot of the variants that the team found overlapped with mutations that are already known to play a role in severe growth disorders, making the researchers more confident about their findings. The results could be used to potentially treat such disorders in the future, Hirschhorn says. For example, a drug that blocks STC2 may have a similar effect to what growth hormones do now. Of course, such promises are still a long way off.
In fact, there are still many more variants associated with height that have yet to be discovered, Hirschhorn says, and analyzing the DNA of more and more people might eventually help. “We have another study we just launched where we’re hoping to get up to 2 million people’s worth of data,” says Hirschhorn.