IMEX   05356
INSTITUTO DE MEDICINA EXPERIMENTAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Comparison between VWF:RCo and VWF:CB in a 2B VWD cohort
Autor/es:
PAIVA J; BLANCO AN; KEMPFER AC; SANCHEZ-LUCEROS A; WOODS AI.; ALBERTO MF; LAZZARI MA
Lugar:
Montpeliere
Reunión:
Congreso; Congress of ISTH-SSC; 2016
Resumen:
Background: In type 2B von Willebrand disease (2BVWD) the von Willebrand factor has increased affinity for platelet glycoprotein Ibα, due to the presence of mutations in the A1 domain. The loss of high molecular weight multimers (HMWM), VWF:RCo/VWF:Ag ratio (RCo/Ag) >0.6 are frequent findings.Aims: To compare VWF:RCo and VWF:CB, RCo/Ag and VWF:CB/VWF:Ag (CB/Ag) in a group of 2BVWD patients (pts) (n=23). Four pts were diagnosed as atypical 2B VWD (normal multimeric profile and platelet count) (p.P1266L and pM1304V), and 19 as typical 2BVWD (absent HMWM) (p.R1306W, p.R1308C, p.S13010F, p.V1316M).Methods: VWF:RCo was assayed by aggregometry using fixed-washed platelets; VWF:CB was assayed by ELISA (collagen type 1).Results: Atypical 2BVWD: VWF:RCo=34±17.6 IU/dL, RCo/Ag=1.01±0.2. Pts with normal RCo/Ag=100%. VWF:CB=31.2±16.3 IU/dL, CB/Ag=0.95±0.4. Pts with normal CB/Ag (>0.6)=100%. VWF:CB and CB/Ag were lower than VWF:RCo and RCo/Ag respectively, but without significant difference (P=0.8 and 0.9).Typical 2BVWD: VWF:RCo=32.3±28.1 IU/dL, RCo/Ag=0.58±0.3. Pts with normal RCo/Ag=36.8%. VWF:CB=18.9±17.5 IU/dL, CB/Ag=0.35±0.17. Pts with normal CB/Ag=10.5%.VWF:CB was lower than VWF:RCo, but without significant difference (P=0.08). CB/Ag was significant lower than RCo/Ag (P=0.006). Percentage of pts with normal CB/Ag was lower than those pts with normal RCo/Ag but not significant (p=0.12). Statistical difference was found in CB/Ag between atypical vs typical pts (p=0.000).Conclusions: VWF:CB and CB/Ag were found lower than VWF:RCo and RCo/Ag respectively. However, the differences were not statistically significant, but they became evident within those patients with absent HMWM. VWF:RCo levels would be overestimated in 2B VWD, due to this known gain-of-function of VWF-mutant in A1-domain, whereas VWF:CB evaluates VWF-collagen binding and is impaired by VWF-mutants in A3-domain, and also the absence of HMWM. We think that difference in CB/Ag between atypical and typical pts is closely related to the multimeric pattern.