EGLN1 was identified by both,
After running the XP-EHH and iHS testing EGLN1 was determined to be a gene that was undergoing local positive selection. Meaning that the gene was currently providing an adaptive advantage to the person who had it, and was increasing in occurrence in that population.
It is plausible that the diminished Hb levels found in Tibetans offset complications associated with sustained high Hb levels (for instance, hyperviscosity) seen in non-Tibetans exposed to high-altitude conditions (10, 11). Alternatively, decreased Hb levels could be a side effect of other phenotypes that are the actual targets of natural selection.
Overall, the decreased hemoglobin levels seen in the Tibetan highlanders may be the result of variants in PPARA and EGLN1 haplotypes. However, the decreased hemoglobin levels could a side effect of a currently unknown phenotype, which may be the actual target of natural selection.