The previous studies have reported that EPAS1 and EGLN1 are responsible for a relatively low hemoglobin concentration, which may be diluted by increased plasma volume (Stembridge et al., 2019), in Tibetan highlanders because it protects against the development of high-altitude polycythemia due to elevated red blood cell volume, while positive natural selection may have acted independently on EGLN1 in Tibetan and Andean highlanders (Bigham et al., 2010). This evidence concerns the gene EGLN1 and polycythemia.