14 DAY TRIAL // A large-scale collaborative study has identified new genetic alterations that determine how tall a person will be, and these uncommon variants could provide insight into the genetic structure of other complex features.
In order to look for genetic variants linked to adult height, the researchers had to carry out a very complex analysis, so they enrolled over 100,000 individuals in their study.
Dr. Brendan Keating, from The Children's Hospital of Philadelphia, explained: “we set out to replicate previous genetic associations with height and to find relevant genomic locations not previously thought to underpin this complex trait.”
In the end, the authors found 64 height-associated variants, among which, two would have never been noticed if it wasn't for such a wide sample size and the inclusion of direct genotyping of uncommon single-nucleotide polymorphisms (SNPs).
Environmental factors can influence the height attained by an adult, but the specific alleles that he/she inherits are the ones that clearly establish their stature.
The thing is that the genetics of height are still not fully understood, and Dr. Hakon Hakonarson, also from The Children's Hospital of Philadelphia, explains:
“All of the variants needed to explain height have not yet been identified, and it is likely that the additional genetic variants are uncommon in the population or of very small effect, requiring extremely large samples to be confidently identified.”
If the size of the study sample is large enough, it is possible to identify genotyping arrays with SNPs that are relatively rare and present in less than 5% of the population, that can capture new signals and disease variants, the common SNP arrays would have missed.
Dr. Keating concluded that “the increased power to identify variants of small effect afforded by large sample size and dense genetic coverage including low-frequency SNPs within loci of interest has resulted in the identification of association between previously unreported genetic variants and height.”
This research was published by Cell Press on December 30, 2010, in the American Journal of Human Genetics.