Effect of the Polymorphic Variant p.D1472H on the Platelet-Dependent VWF Activity Assays

Area of Science:

• Hematology
• Clinical Chemistry
• Molecular Diagnostics

Background:

• The von Willebrand factor (VWF) p.D1472H variant can falsely lower ristocetin cofactor (VWF:RCo) levels due to impaired VWF-ristocetin binding.
• Accurate assessment of VWF activity is essential to prevent misdiagnosis of von Willebrand disease.

Purpose of the Study:

• To evaluate the impact of the VWF p.D1472H variant on the VWF:GPIbR latex immunoassay (LIA).

Main Methods:

• Investigated 150 subjects for VWF:Ag and platelet-dependent VWF activity using four assays: VWF:GPIbR LIA, VWF:GPIbR CLIA, VWF:RCo automated, and VWF:GPIbM LIA.
• Genotyping for the p.D1472H variant was performed using Sanger sequencing or next-generation sequencing (NGS).

Main Results:

• Subjects with the p.D1472H variant showed significantly lower VWF activity/VWF:Ag ratios with VWF:RCo assays (p < 0.0001).
• No significant difference in VWF activity/VWF:Ag ratios was observed between variant carriers and non-carriers using VWF:GPIbR LIA (p = 0.63) or VWF:GPIbR CLIA (p = 0.31).
• VWF:GPIbM LIA showed significantly lower ratios in p.D1472H (+) subjects (p = 0.00052).

Conclusions:

• VWF:GPIbR LIA provides reliable results unaffected by the p.D1472H variant, aiding in differentiating VWF quantitative from qualitative deficiencies.
• VWF:RCo assays are compromised by the p.D1472H variant, while VWF:GPIbR CLIA remains unaffected.
• VWF:GPIbM LIA results are significantly impacted by the p.D1472H variant.