How do you interpret a low VWF activity/antigen ratio, when both activity and antigen levels are above 50%?

This discrepancy is most likely caused by heterozygosity for a VWF variant that either causes VWD type 2M, with defective binding to GPIbalpha, or interferes with the binding of ristocetin, assuming that the activity represents ristocetin cofactor activity. The presence of a bleeding history suggest...