You can’t control your height, but 12,000 genetic variants probably do
You have little control over how tall you grow. Height is determined by genetic variation-lots of genes. Research in 2020 found that 10,000 genes could possibly explain differences in human height. The international GIANT consortium has teamed up with the same statistical geneticists to examine additional genetic links to height.
In the largest genome-wide association study for height to date, they’ve updated their calculations, adding 2,111 more genetic variants that influence a person’s stature, according to the report published Wednesday in the journal Nature. About 40 percent of the differences in height from people of European ancestry were explained by the identified genes.
There is a common misconception that certain traits like height, intelligence or eye color have a few “master genes”. Rebecca Darrah ,, an associate professor of genetics at the Case Western Reserve University School of Medicine, was not involved in the study. In reality, these traits are determined by thousands of genetic factors that interact with the environment. “This fascinating study shows that there are actually over 12,000 distinct genetic variants that contribute to height in European populations,” Darrah says, “and likely many, many more than that for even more complex traits like weight.”
The paper’s authors highlight
Height as a model trait that is worth studying. Eirini Martouli , is a senior lecturer in computational biology at Queen Mary University of London. He is also the co-first author of this study. Height is easy to measure. Adult height does not change over time like weight and IQ. It also has high heritability which means that your parents are more likely to pass down genes that affect height. However, genes are not the only factor that predict height. The environment, such as lack of dietary protein and exposure to certain infectious diseases and exercise, can also influence the person’s growth.
With the GIANT consortium, the team expanded their sample size from an initial 700,000 to 4.1 million to now 5.4 million people from 281 contributing studies. This study was different from previous genetic research that only sampled the genomes individuals of European ancestry. It included more than one million participants from East Asian, Hispanic and South Asian ancestries.
Based on the 5 million DNA samples, the study found 12,111 single-nucleotide polymorphisms (SNP)–single base substitutions in a DNA sequence–that could explain differences in height, making up about 21 percent of the genome’s length.
Human genetic materials includes more than just the actual genes. Most of the identified genetic variants that influence height exist in 7,209 non-overlapping segments outside the genes. These are proteins that control how genes are expressed. These are “likely related” to subtler changes, Darrah said. This could explain why most people and everyone in the study have heights within a normal range. She says that genetic conditions like dwarfism or overgrowth can be caused by dramatic genetic mutations in these areas.
Prior to the 2020 study, research in twins indicated that genes explained about 60 to 80 percent of height differences. The study authors predicted genetic variants could influence 50 percent of variations in height. Indeed, the 12,111 genes explained differences in height for 40 percent of people of European ancestry. However, the identified genes explained only 10 to 20 percent of height variations in those with non-European ancestry.
While this study had an enormous sample size, a lack of geographical diversity among non-European populations remains, pointed out Karoline Kuchenbaecker, a professor of genetic epidemiology at the University College London, in an editorial accompanying the Nature study. The research included data on people of African descent but only 0.4% of the participants actually came from Africa. Kuchenbaecker claims that Africa’s diversity is likely to be missed because genes are affected by the environment.
Marouli believes future work should better capture the ancestral diversity of non European populations. She says, “Increasing the number non-European ancestry individuals is essential to improve prediction accuracy. It may also help to find genetic variants specific to certain groups.” The genomic understanding of height could allow clinicians to diagnose and treat genetic conditions that can cause significant changes in a person’s height.