Scientists discover which genes determine your height

December 29, 2014 - 06:23

Your height is the result of an incredible number of small variations in your genetic material. Scientists have now identified these variations by analysing data from more than 250,000 people.

Scientists have studied how genetic variants influence human height. They identified more than 697 genetic variants that all contribute to the height of a person. (Photo: Shutterstock)

If you are more than 190 centimetres tall it’s not just the result of a good posture and growth boosts from vegetables and wholemeal.

Your genes determine no less than 80 per cent of your height and new research shows that the combination of several thousand ordinary genetic variations determines whether your trousers will always be a bit too short or you will be forever shopping in the kids’ department.

In a new study published in Nature Genetics, researchers have proven that no less than 697 small variations in our genomes influence our height.

A more complete picture of height

The study, which is the result of a survey of the genomes and height of more than 250,000 people, gives a picture of how human height is determined and which genes play a part in the process.

According to one of the scientists behind the study, the project is an example of basic scientific work that can form the basis of more research in future.

“Now that we know so many genes and genetic variants that influence height, we have a more complete picture of the process that ultimately determines the height of an individual,” says senior researcher Bjarke Feenstra with the department of epidemiology research at Statens Serum Institut (SSI), who contributed to the new study.

“For instance we could take a look at the roles genes play in early childhood or in the teenage years, and we could look into which types of tissue the various genes influence,” he says.

Professor: exciting study

Clinical professor of growth and reproduction and Head of Department at the Department for Growth and Reproduction at Rigshospitalet, Copenhagen University Hospital, Anders Juul did not contribute to the new study but agrees with Feenstra that scientists can use the study to learn a lot about the genes related to growth.

“It’s an exciting study with an enormous amount of DNA samples. The study gives us new knowledge about the most significant genes associated with height,” says Juul.

“It offers an explanation for 60 per cent of the variation in the height of individuals.  The results can be used to identify potential new biological signalling pathways that have a bearing on longitudinal growth,” he says.

Variation makes bones a single millimetre longer

Not surprisingly, during the study the scientists discovered that genetic variations that influence bones and connective tissue are especially significant when it comes to the determination of height.

Small variations in the DNA’s molecular building blocks cause the bones to grow to a given length with a single genetic variation, while another genetic variation will cause the bones to be a single millimetre longer on average.

The combinations of the many small variations and the many single millimetres are accumulated and ultimately amount to the great variation in human height where anywhere between 150 cm and 200 cm is considered normal.

The scientists have identified hundreds of such variations -- but according to Feenstra there are many more.

“We’ve identified 697 common genetic variations, but there are certainly many more that are either rare or influence height less. We estimate that the accumulation of the effect of thousands of genetic variations determines genetic contribution to a person’s height, and that a major part of these will be common genetic variations,” he says.

Many features determined by several genes

Height is not the only thing that’s determined by thousands of genetic variants. The same goes for BMI and cholesterol levels.

However, when discussing height, BMI and cholesterol levels it is important to distinguish between the common genetic variants and the disease-causing genetic variants.

For instance, in combination, the common genetic variants will account for the variation in height in a group of males, while a single rare disease gene can cause dwarfism.

Similarly, common genetic variants account for the variations in the BMI of people of normal weight, whereas a few rare genetic variants cause obesity.

Thus, thousands of common genes form a ‘normal’ starting point, while a few undesirable genetic variants can wreak havoc, changing the outcome completely.

Dwarfism caused by single gene

By identifying 697 places in the genome where small changes in the composition of the DNA’s building block influence height, the scientists can now start investigating the effects of the individual genes.

Some genes are already known from conditions such as dwarfism, where a dysfunction in the gene leads to a dramatic growth inhibition.

“It’s interesting that in several such genes with well-known, extremely rare mutations with a dramatic influence on growth and height we also find completely ordinary genetic mutations that have a marginal effect on height,” say Feenstra.

He explains that the study has identified decisive genetic variations several places in some of the same genes.

“The close to 700 genetic variations are concentrated around 423 different locations in the genome. This means that in many instances several different independent mutations influence the same gene.  And the results actually suggest that even more variations may exist in these concentrated genome regions, so that down the line we will have an even better understanding of the genetic architecture behind height,” says Feenstra.

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Read the original story in Danish on Videnskab.dk

http://videnskab.dk/krop-sundhed/vildt-sa-mange-gener-afgor-din-hojde

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Translated by
Iben Gøtzsche Thiele

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