Ever wonder how much of your height you inherited from your parents?
A large-scale genetic study published recently in the journal Nature is helping shed some light on the factors that determine whether a person grows to be 6-feet-1 or 5-feet-2.
While scientists already had a good idea of the most common genetic factors that contribute to height, the new findings uncover a number of rare genetic alterations that can play a surprisingly major role in human growth.
Using data from the Genetic Investigation of Anthropometric Traits consortium (a group also known as GIANT), scientists from the Broad Institute at MIT and Harvard analyzed genetic information from more than 700,000 people, discovering 83 DNA changes that play a part in determining a person’s height.
In their previous work, the same research team identified nearly 700 common genetic factors linked with height. Now, they’ve identified a number of rare genetic variants for human growth that have an even larger effect than most common factors. For some people, these rare DNA changes may account for height differences of up to a full inch.
“Overall, common variants still contribute more to height than rare variants,” Dr. Joel Hirschhorn, the study’s lead author and a professor of pediatrics and genetics at Boston Children’s Hospital and Harvard Medical School, told The Huffington Post. “But, for the person who happens to carry one of the rare variants, the impact can be much greater than for common variants. For the variants we looked at, this was up to almost an inch… as opposed to a millimeter or less for the common variants.”
Using a new technology called the ExomeChip, the researchers were able to scan the genomes of large populations to find rare markers that correlated with a particular height. They identified 51 uncommon variants found in less than 5 percent of people, and 32 rare variants found in less than 0.5 percent of the population.
With the addition of these uncommon variants, geneticists can now account for 27 percent of the genetics determining height ― up from 20 percent based on earlier studies.
Heritability is by far the largest factor contributing to individual height.
“Today, in places where most people get enough nutrition in childhood to grow to their potential, about 80 percent or more of the variability in height is due to genetic factors that we inherit from our parents,” Hirschhorn explained.
According to the study’s authors, this method of testing rare genetic variants could be used to investigate uncommon DNA changes involved in other aspects of human health.
“Looking at rare variants in genes was helpful in understanding the biology of human growth,” Hirschhorn said. “With a big enough study, similar approaches could be valuable in understanding the biology of many diseases, which could help guide better treatments.”