Your search term EPO returns the following data from GWAS Central:
Phenotype search results:
Search term EPO was not recognised as a MeSH/HPO phenotype term or synonym

Gene/region search results:
18 Study Datasets reported containing markers in gene or region EPO (no 5′ and no 3′ flanks) with -log p ≥ 0View and refine results..
5 Markers in gene or region EPO with -log p ≥ 0View and refine results..
4 Texts contain the keyword EPOView and refine results..

Studies search results:
4 Studies contain the keyword EPOView and refine results..

Marker search results:
Search term EPO was not recognised as a marker identifier or identifiers