ATF4 and hydrops fetalis: When Atf4/ISR genes were tested against gene expression in HF and MAZ1310 (gene set: Atf4/ISR genes, phenotype: HF treatment), GSEA indicated a high statistical significance (Enrichment Score = 0.962, p = 0.000, Normalized Enrichment Score (NES) = 1.27 and FDR q-value = 0.000; Figure 5).