Expression profiling of iPSC-derived CD33⁺myeloid progenitors identified a downregulated genetic interaction network in Kostmann disease. The granulocyte-specific gene set is positively enriched in (A) HAX1^WT/WT and (B) HAX1^corrected myeloid progenitors compared with HAX1^W44X cells. (C) When comparing HAX1^WT/WT and HAX1^corrected cells, no significant enrichment could be observed, suggesting that those groups show similar granulocytic expression patterns. ES, enrichment score, FDR, false discovery rate; FWER, family-wise error rate; NES, normalized enrichment score. (D) Heatmap (left) of the 533 myeloid-specific genes (leading edge subsets) that were downregulated in HAX1^W44X-iPSC–derived myeloid progenitors as compared with HAX1^WT/WT- and HAX1^corrected-iPSC–derived cells. Those were used to form a gene interaction network (supplemental Figure 9B). The downregulated gene interaction partners of HAX1 and HCLS1 in HAX1^W44X-iPSC–derived CD33⁺ granulocytic progenitors are shown (right). (E-F) 3,3′-diethyloxacarbocyanine iodide (DiOC₂(3)) mean fluorescence intensity (MFI) of (E) TRA-1-60⁺ iPSCs and (F) CD33⁺ cells during induced myeloid differentiation with or without addition of mitochondrial membrane potential disruptor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Mean ± SD of n = 4-5 experiments are shown. NS, not significant. *P < .05 when compared with HAX1^wt/wt.