PB1244 - Development of Consensus on Standardized Nomenclature for PT-VWD- Joint Project from the ISTH SSCs on Platelet Physiology, VWF and Genomics in thrombosis and Haemostasis

Background: The issue of nomenclature in PT-VWD was discussed on several occasions. Several names were proposed: Pseudo-VWD, PT-VWD, ‘VWD-mimic’ disorder, and Platelet type pseudo VWD. Of all, platelet-type VWD has gained the widest acceptance. This name may be problematic since the diagnostic pathway of patients often starts with VWF assays, but the disorder is due to a gain-of-function mutation in the platelet GP1BA gene and thus the therapeutic approaches are quite different than VWD.

Aims: To re-visit and standardize the disease’ nomenclature in consultation with the ISTH members and scientific community.

Methods: A working group was formulated under the auspice of 3 ISTH subcommittees, explored issues around nomenclature and proposed possible names with input from a panel of 15 worldwide experts. A focused 4-questions survey proposed 8 names with justifications for each, was administered online via ISTH REDCap and emailed to ISTH members of the three SSCs between JUL-AUG 2021. Participants were asked to rank their top three choices.

Results: We received 155 responses (VWF SSC members: 74%, PLT: 45%, Genomics: 28%). 103 (68%) respondents supported the need for name change. “Platelet GP1BA gain-of-function disorder” received the highest support (28%) followed by “Platelet type-Von Willebrand disease” (24%) and “Platelet type-pseudo-Von Willebrand disease” (13%). Of the 43 respondents who contributed to the top choice (Figure 1), 53% were members at the VWF SSC, 25% from Platelet SSC and 22% from Genomics SSC. The new reporting system for genetic variants (starting from Met) was supported by 31%. 91% recommended the disease be discussed jointly by all three ISTH SSCs.

Conclusion(s): There is international awareness of the need for standardization of the nomenclature for PT-VWD. The terminology “Platelet GP1BA gain-of-function disorder” gathers most support, and reflects the protein and gene involved and highlights the pathologic nature of the functional defect.