If only one of VWF:GPIbB/Ag and VWF:CB/Ag is low (and confirmed upon repeat), then this is inconsistent with loss of HMWM VWF, and so type 2A or 2B or PT VWD is unlikely, and instead 2M VWD is likely. The gene discussed is GP1BB; the disease is von Willebrand disease (hereditary or acquired).