The greatest evidence of ancestry-correlated heterogeneity (after accounting for the use of a universal blood-based test) was observed at the CDKAL1 locus (PHET = 3.4 × 10−5), where the lead SNV demonstrated stronger effects on GDM in GWAS of East Asian ancestry than in other populations, despite the risk allele being common in all ancestry groups (Supplementary Material, Fig. S5, Table S4). This evidence concerns the gene CDKAL1 and gestational diabetes.