Low VWF with a VWF:GPIbM/VWF:Ag ratio of <0.7 is distinct from type 2M VWD. (A) The prevalence of blood group O and female sex among patients with low VWF with a VWF:GPIbM/VWF:Ag ratio of <0.7 (n = 25) and among those with type 2M VWD (n = 35). The P values were determined using χ² tests. (B) The prevalence of likely pathogenic VWF sequence variants identified among patients with low VWF with a VWF:GPIbM/VWF:Ag ratio of <0.7 and among those with type 2M VWD. The P values were determined using χ² tests. (C) Illustration of likely pathogenic VWF sequence variants identified among patients low VWF with a VWF:GPIbM/VWF:Ag ratio of <0.7 (above the VWF monomer) in comparison with those with type 2M VWD (below the VWF monomer). Some variants were present in >1 patient. (D) The FVIII:C/VWF:Ag ratio (a marker of VWF synthesis/secretion) and (E) the VWFpp/VWF:Ag ratio (a marker of VWF clearance) were compared between patients with low VWF with a VWF:GPIbM/VWF:Ag ratio of <0.7 and those with type 2M VWD. The P values were determined using independent t tests. (F) The proportion of patients with complete response to desmopressin among patients with low VWF with VWF:GPIbM/VWF:Ag ratios of <0.7 and those with type 2M VWD. The P values were determined using χ² tests.