At the single gene level, nine genes were associated with ARDS mortality through a systems biology approach including HDAC1, encoding a histone deacetylase (HDAC) previously linked to acute inflammatory disorders11–13 including acute lung injury with HDAC inhibitors shown to prevent endothelial hyperpermeability14, the major pathophysiological defect in acute lung injury15–17. The gene discussed is HDAC9; the disease is acute respiratory distress syndrome.