We propose that to prevent uncontrolled motility of PNH-affected HSPCs and their egress from BM niches, the use of S1P–S1P receptor axis inhibitors (e.g. fingolimod) 7 with CC inhibitors may be considered for treatment of PNH 9,25. The gene discussed is MBTPS1; the disease is paroxysmal nocturnal hemoglobinuria.