First common height gene identified
For the first time, scientists have identified one of the many genes which commonly influence our height. The work, which was partly funded by the EU, is published online by the journal Nature Genetics. It has been known for some time that around 90% of the variation in human height is due to genetic factors, rather than environmental factors such as diet. Yet although scientists have discovered rare gene variants which affect height in very small numbers of people, until now the common gene variants which affect the height of the majority of the population have remained unidentified. The scientists studied the DNA of 5,000 people, looking for tiny differences in the genetic code which appeared more often in tall people than shorter people. This revealed that people with a certain version of a gene called HGMA2 were likely to be taller than people with a different version of the gene. The results were confirmed by a follow-up study of over 19,000 people. We all have two copies of HGMA2, one from each parent. The study revealed that having two 'tall' versions of the gene adds around a centimetre to your height compared to someone with two 'short' variants. Having one copy of the 'tall' variant adds around half a centimetre of height. According to the scientists, its affect on growth can be seen in individuals as young as seven years of age. 'Height is a typical 'polygenic trait' - in other words many genes contribute towards making us taller or shorter,' explains Dr Tim Frayling of the Peninsula Medical School in Exeter, UK, a co-leader of the research. 'Clearly our results do not explain why one person will be 6'5'' [1.96 metres] and another only 4'1'' [1.24 metres]. This is just the first of many that will be found - possibly as many as several hundred.' Around 25% of the white European population is estimated to have two 'tall' versions of the gene, while 25% have two 'short' versions. Little is known about the precise role of HGMA2, but the scientists believe that it could influence height by causing increased cell production. This is of interest because tall people are at a slightly greater risk of certain cancers, and cancers are caused by unregulated cell production. 'There appears to be a definite correlation between height and some diseases,' comments Dr Mike Weedon of the Peninsula Medical School. 'For example, there are associations between shortness and slightly increased risks of conditions such as heart disease. Similarly tall people are more at risk from certain cancers and possibly osteoporosis.' In children, being short can sometimes indicate the presence of a serious medical condition, and height, or the lack of it, is a common reason for sending children to a specialist. '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,' says Dr Joel Hirschhorn of the Broad Institute of Harvard and MIT (Massachusetts Institute of Technology) in the US. Earlier this year many of the researchers involved in this study revealed the discovery of the first common gene linked to obesity. EU funding for the height gene research came from the Sixth Framework Programme (FP6) EURODIA (Functional genomics of pancreatic beta cells and of tissues involved in control of the endocrine pancreas for prevention and treatment of type 2 diabetes) project and the Fifth Framework Programme (FP5) GenomEUtwin (Genome-wide analyses of European twin and population cohorts to identify genes in common diseases) project.