Genomics researchers, seeking to replicate another group's discovery of an important gene associated with obesity, have further refined the signal to a particular variant in DNA that may be more helpful in identifying this gene's role in obesity in various human populations worldwide.
The finding suggests that the gene variant, identified in DNA from African American children, may be a tag of an ancient mutation that first arose in Africa, where humans originated.
The research team, led by Struan Grant, Ph.D., and Hakon Hakonarson, M.D., Ph.D., both of the Center for Applied Genomics of The Children's Hospital of Philadelphia, was studying the FTO gene, identified by a British group in 2007 as raising the risk of adult and childhood obesity. Although environmental influences are certainly important, family studies have indicated that obesity has a genetic component as well.
The research team, from Children's Hospital and the University of Pennsylvania School of Medicine, reported its findings in the March 12 issue of the journal Public Library of Science One.
The 2007 British group had originally found the FTO gene variant among obese Caucasians. Using samples from Caucasian and African American children, who were either obese or not, the Children's Hospital group used a genetic screening technique to replicate the previous finding. They found the same gene variant among Caucasian children, but not among the African American children.
Instead, a second variant, found in both Caucasians and African Americans, was the only marker significantly linked to obesity among the African American children. Both variants were changes to a single chemical base along the DNA strand, which geneticists call single nucleotide polymorphisms, or SNPs.