Here we present a dizygotic twin pregnancy complicated with one hydrops (including chylothorax, fetal lymphascites and polyhydramnios) and with a de novo mutation in the ITGA9 gene (p.G404S); this index case (Ind; Figure 1) was successfully managed by antenatal OK-432 pleurodesis, combined with aggressive neonatal intensive care. This evidence concerns the gene ITGA9 and Chylothorax.