November 24, 2011

Short People Short On Genes

We all understand that genetics determine our height, but scientists want to dig in deeper and find which genes might be directly responsible. Scientists have released a study, published by Cell Press in the December issue of the American Journal of Human Genetics, suggesting that uncommon genetic deletions are associated with short stature.

Researchers are focusing on genetic abnormalities, known as copy number variants (CNV), which are alterations within the chromosome that determine if a cell has too many or too few copies of a slice of DNA, Nick Collins writes for the Telegraph.

Height is a highly heritable trait that is associated with variation in many different genes. “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 senior study author, Dr. Joel N Hirschhorn, from Children´s Hospital Boston and the Broad Institute.

“It has been estimated that about half of height variation could eventually be accounted for by the sorts of variants we´ve been looking at, so it is possible that other types of genetic variants, such as copy number variants (CNVs), may also contribute to the genetic variation in stature.”

Everyone has some of these deletions in their genome, covering thousands of individual components of DNA, while others have millions. One eighth of an inch in height was discovered missing for every million individual CNV deletions in people, researchers found after studying 12,000 individuals.

Hirschhorn, said it showed a small but firm link between the amount of genetic material missing and a decrease in height. This trend stood up regardless of which genes were missing, he added.

“Each deletion takes out some letters of the DNA sequence — most have no effect but some have a modest effect. With both areas that have an effect on height and those that do not, we found a small relationship between deletions and short stature.”


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