The data presented here describes MMRN1 as a novel ligand for VWF A1A2A3 region, and suggests that impaired VWF binding to MMRN1 could occur in some forms of VWD, reducing VWF-GPIbα-dependent platelet adhesion at sites of vessel injury. Here, MMRN1 is linked to von Willebrand disease (hereditary or acquired).