We started by downloading all the associations in the GWAS Catalog [23] (last accessed in February 2012, see Materials and Methods), which represents a total of 7,145 associations with P<10−5 reported in 1,171 papers. To study trans-ethnic replicability across diseases, we first focused on GWAS performed upon the two most studied ancestral groups: Europeans and East Asians. We avoided quantitative traits, such as height or BMI, because they could be subject to different evolutionary pressures than disease traits and, thus, may present different replicability patterns. We selected for analysis diseases for which GWAS had been performed several times. In particular, we required (i) two or more GWAS with peoples of the same ancestry group; and (ii) at least one GWAS with subjects from the other ancestry group. A total of 28 diseases and 277 GWAS (206 European and 71 East Asian) fulfilled our criteria (average ∼10 papers per disease, range = 3–27 papers; see Materials and Methods and Tables S1 and S2). We further performed an exhaustive search of the literature to detect any GWAS published before February 2012 but
