Tibetans and some Ethiopians have both evolved a dampened response to low oxygen, explained study co-authors Anna Di Rienzo and Gorka Alkorta-Aranburu of the University of Chicago.
The researchers wanted to pinpoint the genetic changes that enable Ethiopians to thrive in thin air, and to see if the same genes play a role for Ethiopians as found in recent studies for Tibetans.
To find out, they analyzed the genomes of nearly 260 Ethiopian villagers belonging to two ethnic groups: the Oromo, who began settling at high altitude in the Bale Mountains of southeast Ethiopia about 500 years ago, and the Amhara, who have lived at high altitude in the Semien Mountains of northwest Ethiopia for at least 5,000 years.
Research by Beall and colleagues in the early 2000s revealed that Oromo cope with thin air in much the same way that lowlanders visiting high altitude do i.e., by making more hemoglobin.
In contrast, Amhara highlanders whose ancestors have inhabited mountainous regions for thousands of years longer than the Omoro are able to maintain blood hemoglobin levels that are roughly 10% lower than Omoro living at the same altitude.
In a study to appear in the December 6, 2012 online issue of the journal PLoS Genetics, a team led by Beall, Di Rienzo and Alkorta-Aranburu analyzed both groups' DNA, which was extracted from blood and saliva samples donated by Amhara and Omoro villagers born and raised at high (3700-4000m) and low (1200-1560m) elevations.
Using a statistical technique called a genome-wide association study, the researchers scanned the genomes of highland and lowland Ethiopians from both ethnic groups in search of variants associated with hemoglobin levels
|Contact: Robin Ann Smith|
National Evolutionary Synthesis Center (NESCent)