Abstract Number: PB1565
Meeting: ISTH 2020 Congress
Theme: Platelet Disorders and von Willebrand Disease » VWF and von Willebrand Factor Disorders - Clinical Conditions
Background: Type 3 Von Willebrand disease (VWD) is a rare autosomal recessive disorder characterised by undetectable levels of Von Willebrand Antigen (vWF:Ag) and reduced levels of Factor VIII. Patients with type 3 VWD are homozygous or compound heterozygous for two null alleles causing virtually complete deficiency of Von Willebrand factor (VWF). Carriers of type 3 VWD are usually asymptomatic with VWF 50% of normal. PFA100/200 (platelet function analyser; Dade-Behring, Marburg, Germany) has been found to have high sensitivity to VWF and VWD. However, there is no data available for carriers of type 3 VWD with PFA200.
Aims: To evaluate carriers of type 3 VWD with PFA200.
Methods: This is a retrospective study. Data was collected from patients who presented to a tertiary hospital in South India from January 2016 to December 2019. Parents were evaluated as part of the diagnostic workup and following tests were performed – complete blood count, closure time (CT) in PFA200 with COL/ADP and COL/EPI cartridges, blood group, APTT, Factor VIII, vWF:RCo and vWF:Ag. Carriers with haematocrit < 30% and platelet count < 100000/cumm were excluded from PFA analysis. Reference range for CT for COL/ADP and COL/EPI was 68-142 secs and 89-167 secs respectively.
Results: 98 carriers from 63 type 3 VWD patients were included in the study.The summary of the results are shown in Tables 1 & 2. 68 % of the carriers had prolonged CT with either COL/ADP or COL/EPI, which was more pronounced in O blood group carriers. 96% of the carriers with vWF:RCo < 50% had prolonged CT. Surprisingly, 55% of carriers had prolonged CT even with vWF:RCo >50%.
Conclusions: PFA100/200 assesses primary hemostatic function under high shear conditions and is very sensitive to alterations in VWF. The significance of abnormal PFA200 in type 3 VWD carriers needs to be validated by further studies and molecular analysis.
| Factor VIII (IU/dL) Median (IQR) | vWF:RCo (%) Median (IQR) | vWF:Ag (U/dL) Median (IQR) | COL/ADP in PFA200 in (secs) Median (IQR) | COL/EPI in PFA200 (secs) Median (IQR) | |
| All carriers | 125.8 (105.4 – 166.9) | 60 (39.2 – 79.4) | 60.5 (45.6 – 79.3) | 145 (113 – 186) | 193 (151 – 281) |
| O blood group carriers | 109.9 (93.9 – 129.2) | 44 (32.3 – 62.3) | 47.1 (37.8 – 129.2) | 166.5 (120 – 220) | 221 (181 – 299) |
| Non O blood group carriers | 149.9 (111.5 – 187.5) | 68.6 (54.3 – 83.3) | 69.7 (54.3 – 87.6) | 128 (111 – 156) | 171 (145 – 238) |
[Summary of carriers of type 3 Von Willebrand disease.]
| Prolonged COL/EPI (%) | Prolonged COL/ADP (%) | Either COL/ADP or COL/EPI prolonged(%) | Both COL/ADP and COL/EPI prolonged (%) | |
| All carriers (85) | 54/85 (63.5%) | 42/83 (50.6%) | 58/85 (68.2%) | 38/85 (44.7%) |
| O blood group carriers (35) | 27/35 (77.1%) | 24/35 (70.5%) | 29/35 (82.8%) | 21/35 (60%) |
| Non O blood group Carriers (48) | 28/48 (52%) | 18/47 (38.2%) | 27/48 (56.2%) | 16/48 (33.3%) |
[Percentage of carriers of type 3 Von Willebrand disease with prolonged closure time in PFA200]
To cite this abstract in AMA style:
Geevar T, Gautam Dave R, Singh S, V R, N A F, Srivastava A, C Nair S. Evaluation of Carriers of Type 3 von Willebrand Disease with PFA200 [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/evaluation-of-carriers-of-type-3-von-willebrand-disease-with-pfa200/. Accessed September 21, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/evaluation-of-carriers-of-type-3-von-willebrand-disease-with-pfa200/