It’s a question that has fascinated geneticists for decades: why are some people taller than others?
Now a new study of 700,000 people has revealed 83 DNA changes which have a big impact on height.
The alterations are uncommon, but some adjust height by more than 2cm. More common variants relate to differences of less than a millimetre.
“While our last study identified common height-related changes in the genome, this time we went for low-frequency and rare changes that directly alter proteins and tend to have stronger effects,” said Joel Hirschhorn, MD, PhD, of Boston Children’s Hospital.
Conducted by nearly 300 research groups around the world, the Genetic Investigation of Anthropometric Traits (GIANT) study is the largest genetic investigation of height ever conducted.
Scientists have now accounted for 27.4 per cent of the heritability of height, mostly explained by common variants.
The study also revealed new biological pathways that influence skeletal growth, including one gene that restricted growth factors in the blood.
“The STC2 protein serves as a brake on human height, validating it as a potential drug target for short stature,” Hirschhorn said.
Researchers used a catalogue of nearly 200,000 less common known variants to find genes associated with traits or diseases.
As much as 60 to 80 per cent of height is influenced by genetics, according to previous research, with the remaining 20 to 40 per cent affected by diet.
According to the team, height is the “poster” child of complex genetic traits, as it’s affected by so many genes working at once.
If you can figure out the genetics of height, disorders that are influenced by several genes should also be easier to understand.
“Mastering the complex genetics of height may give us a blueprint for studying multifactorial disorders that have eluded our complete understanding, such as diabetes and heart disease,” Hirschhorn said.