Short people 'short' on genes

Short people can blame deleted sections of DNA for their diminutive stature, according to a study looking at variations in the genomes of over 12,000 people.

The US group from Children's Hospital Boston noticed a link between smaller people and the amount of genetic material missing in their genomes.

It is widely accepted that height is heritable, but 'despite tremendous recent progress in finding common genetic variants associated with height, thus far these variants only explain about 10 percent of the variation in adult height', explains lead author Dr Joel Hirschhorn.

He believes about half of height variation could be accounted for by differences in the amount of DNA present at particular points in the genome. To investigate, his team looked at specific changes known as copy number variants (CNVs). These are alterations causing certain regions to have either too much or too little DNA. While everyone will have some of these abnormalities in their genomes, some people have millions; and some areas of DNA are more commonly affected than others.

'To investigate whether CNVs play a role in short or tall stature, we conducted a genome-wide association study of copy number in a cohort of children... and we observed an excess of rare deletions in children with short stature', co-author Dr Yiping Shen said.

When the team carried out the same analysis on a larger population they again found an excess of deletions in shorter people. According to the Telegraph, for every million individual deletions, people lost one eighth of an inch in height.

They write in their report, published in the American Journal of Human Genetics, that these findings were not due to any known gene deletion syndromes. They could not, however, make a link between CNVs and tall stature.

'Our findings strongly support the hypothesis that increasing burden of lower frequency deletions can lead to shorter stature, and suggest that this phenomenon extends to the general population', commented author Dr Andrew Dauber.