November 2020 QQ: VWF Activity Assay Responses

Our November, 2020 Quick Question attracted 37 participants. Here is the stem: “Which VWF activity assay is preferred at your facility [check 10-31-20 post]?” The selections were…

1. VWF:RCo: 58% [21]
2. VWF:GP1bR: 3% [1]
3. VWF:GP1gM: 14% [5]
4. VWF:Ab: 3% [1]
5. VWF:CBA: 22% [8]*

The time-honored Ristocetin cofactor assay remains the most prevalent of VWF activity assays. The reference provided in the 10-31-20 post names VWF:GP1bR as Ristocetin-induced binding of VWF to recombinanit GP ib fragment, and VWF:GP1gM as spontaneous VWF binding to gain of function mutant GP Ib fragment. These are the newest of VWF activity assays that offer improved precision compared to VWF:RCo.

*The VWF:CBA tally is approximate, as the poll was corrupted by spam.