New Clues on Genes That Affect Height

Researchers Pinpoint Genetic Variants That May Lead to Differences in Height

By Joanna Broder
WebMD Health News

Reviewed by Laura J. Martin, MD

Sept. 29, 2010 -- Researchers say they've identified more than 100 new genetic variants that influence height.

The study of more than 180,000 people is published in the advance online edition of Nature.

“This paper is the biggest step forward to date in understanding which genetic variants, that differ between people, account for our differences in height,” study researcher Joel Hirschhorn, MD, PhD, says in a news release. Hirschhorn is a doctor at Children's Hospital Boston and an associate professor of genetics and pediatrics at Harvard Medical School.

Understanding the genetics of height is challenging. It's estimated that more than 80% of height variation within a specific group can be attributed to genetics, with the other 20% of variation attributable to the environment. But so far scientists have only been able to account for about 10% of the inherited influences.

Researchers from more than a hundred institutions worldwide that are part of The GIANT (Genome-wide Investigation of Anthropometric Traits) Consortium, an international group, pooled data from more than 180,000 people, including millions of genetic results from 46 separate studies in the U.S., Canada, Europe, and Australia. They then evaluated the participants' DNA samples in search of genetic variants known as single nucleotide polymorphisms or SNPs.

The human genome is made up of more than 3 billion subunits of DNA. Variation in DNA sequences between people is sometimes due to differences in their individual nucleotides, molecules that when joined together make up DNA.

Researchers identified 180 regions of the genome that housed SNPs associated with height. More than 100 of them were identified for the first time.

Rather than randomly occurring throughout the genome, these variants were situated near genes that have been previously shown to be associated with growth.

“We have found clues to how genes related to growth are being regulated by nearby genetic variants as well as identifying new candidates that may play a role in growth,” study researcher Mike Weedon, from the Peninsula School of Medicine and Dentistry at the University of Exeter in England, says in a news release.

This study was what is known as a genome-wide association study, a type of study often criticized for offering data that have no immediate importance. But Hirschhorn and colleagues specifically chose this type of study to try to locate genes related to height, since it casts a wide net by sampling millions of sites of genetic variation in large groups of people. The goal was to find consistent differences in height that are related to specific variants in the genome. These sorts of studies can identify “large numbers of loci [regions] that implicate biologically relevant genes and pathways,” the researchers write.

“Genome-wide association studies are very powerful tools, but even so, we are still some way short of understanding the full details of how differences in our genomes influence common human traits such as height,” Tim Frayling, a professor of human genetics at Peninsula College of Medicine and Dentistry, says in a news release.

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SOURCES: Allen, H.L. Nature, Sept. 29, 2010.News release, Nature.

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