Scientists discover HMGA2. Gives one a good 1 cm more for homozygotes.
People who carry two copies of the “tall” version of the HMGA2 gene are up to 1cm taller than those who carry two copies of the “short” version.
The international team of researchers say the discovery could aid a greater understanding of the link between height and disease.
They predict in the journal Nature Genetics many other genes will now be uncovered that control height.
Although it has long been clear that genetics plays a key role in determining a person’s height, the genes involved have remained a mystery.
The latest study is a collaboration between Harvard University, the Children’s Hospital Boston, Oxford University and the Peninsula Medical School in Exeter.
They analysed the genomes of 5,000 white European patients, who gave DNA samples and details of their height and weight for medical studies into diabetes and heart disease.
They found just one tiny change in the HMGA2 gene had an impact on a person’s height.
The finding was confirmed by searching for the same two key versions of the gene in a further 30,000 patients.
Around 25% of white Europeans carry two copies of the “tall” version of the gene, while a similar proportion have two copies of the “short” version.
Carrying one copy of the “tall” version of the gene adds around 0.5cm to a person’s height, while two copies adds nearly a full centimetre.
Previous research has suggested that HMGA2 plays an important role in human growth.
Rare, severe mutations in the gene cause dramatic alterations of body size in mice and humans.
Researcher Dr Tim Frayling, of the Peninsula Medical School, said: “Height is a typical ‘polygenic’ trait, in other words many genes contribute towards making us taller or shorter.
“Clearly, our results do not explain why one person will be 6ft 5in (192 cms) and another only 4ft 10in (145cms).
“This is just the first of many that will be found, possibly as many as several hundred.”
A greater understanding of the genes behind height could also provide clues about risk of disease.
Taller people are statistically more likely to be at risk from prostate, bladder and lung cancer.
This suggests that the genes that regulate cell growth and division may also play a role in the uncontrolled cell proliferation characteristic of cancer.
Conversely, shorter people are known to have a higher risk of heart disease.
Professor Joel Hirschhorn, an expert in genetics at Harvard, said “This is the first convincing result that explains how DNA can affect normal variation in human height.
“Because height is a complex trait, involving a variety of genetic and non-genetic factors, it can teach us valuable lessons about the genetic framework of other complex traits, such as diabetes, cancer and other common human diseases.”
He added: “By defining the genes that normally affect stature, we might someday be able to better reassure parents that their child’s height is within the range predicted by their genes, rather than a consequence of disease.”