Ultralarge von Willebrand factor multimers and normal ADAMTS13 activity in the umbilical cord blood

Han Mou Tsai, Ravindra Sarode, Katharine A. Downes

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Introduction: Recent studies demonstrate that deficiency of ADAMTS13, the metalloprotease that cleaves von Willebrand factor (VWF) in a shear-dependent manner, causes thrombotic thrombocytopenic purpura (TTP). Previously, ultralarge multimers of VWF were detected in the fetuses, the umbilical cords and the newborns. However, the significance of this finding is unknown. Materials and methods: The activity of ADAMTS13 and the multimer pattern of VWF in the cord blood, as well as the VWF antigenic and ristocetin cofactor levels, were analyzed using previously published methods. The presence of ultralarge multimers was determined by densitometric analysis. Results: On the average, the level of VWF antigen and ristocetin cofactor activity are slightly increased in the newborns (mean±standard deviation, 1.66±0.76 and 1.45±0.64 U/ml, respectively). Ultralarge VWF multimers are detected in 11 of 17 umbilical cord plasma samples. However, the ADAMTS13 is normal (0.99±0.15 U/ml) in all but one sample in which it is mildly decreased (0.71 U/ml). Conclusions: Since ADAMTS13 activity is normal, we speculate that the presence of ultralarge multimers in the umbilical cord blood may be due to the low levels of shear stress in the umbilical circulation. These results may have important implications for understanding the manifestation of ADAMTS13 deficiency during the neonatal period.

Original languageEnglish (US)
Pages (from-to)121-125
Number of pages5
JournalThrombosis research
Issue number2-3
StatePublished - Nov 1 2002


  • ADAMTS13
  • Metalloprotease
  • Proteolysis
  • Shear stress
  • Umbilical cord
  • von Willebrand factor

ASJC Scopus subject areas

  • Hematology


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