A genetic survey of more than 34,000 people has revealed the first gene known to have a decisive effect on height in people of average stature. A change to just a single letter of genetic code is linked to a height boost of almost a centimetre in a healthy person, all other things being equal. Although up to 90% of variation in people’s height is thought to be down to genetics, identifying the genes involved is difficult because there are thought to be hundreds of them, each with an almost imperceptible effect.
Researchers therefore combed through almost the entire genome of nearly 5,000 volunteers in search of tiny changes, called polymorphisms, that correspond to variations in height. Eventually they found a single-letter DNA substitution, buried in a gene called HMGA2, that influences height. People with two copies of the ‘tall’ variant of HMGA2 are, on average, almost a centimetre taller than those with two copies of the ‘short’ version. Those with one copy of each are somewhere in the middle.