ITGA9 and Chylothorax: Therefore, Gene Set Enrichment Analysis (GSEA) [12] was applied to the mRNA expression data from each of the four sample-pairs (Sample 1: Ind-A, fluids from the Ind fetus after fetal treatment; Sample 2: Ind-B, fluids from the Ind fetus before fetal treatment, in the index case carrying an ITGA9 mutation (p.G404S); Sample 3: FC-r, fluids from another similar hydropic case with chylothorax, but without the ITGA9 mutation; and Sample 4: NFC-r, fluids from an additional hydropic case without a chylothorax and no ITGA9 mutation).