title: A Unique Case Involving a Female Patient with Upshaw-Schulman Syndrome: Low Titers of Antibodies against ADAMTS13 prior to Pregnancy Disappeared after Successful Delivery.
abstract: BACKGROUND
  Upshaw-Schulman syndrome (USS) is usually suspected based on severe deficiency of ADAMTS13 activity without ADAMTS13 antibody, but the definitive diagnosis is made by ADAMTS13 gene analysis. We present a unique case of USS with low titers of ADAMTS13 antibodies before pregnancy. Interestingly, titers of ADAMTS13 antibodies decreased to almost undetectable levels after delivery.
  
  
  METHODS
  In patient LL4, the diagnosis of USS was confirmed at age 27 by ADAMTS13 gene analysis. She became pregnant at age 30. During the pregnancy, she received regular fresh frozen plasma (FFP) infusion. Plasma von Willebrand factor levels increase as pregnancy progresses. To prevent platelet thrombi, much more ADAMTS13 supplementation is necessary during late gestation in patients with USS. Therefore, we shortened the interval between and increased the volume of FFP infusions as pregnancy progressed. At 39 weeks, she delivered a healthy baby girl. Before pregnancy, she had low titers of both neutralizing and binding anti-ADAMTS13 antibodies. Despite frequent FFP infusions, titers of the antibodies did not increase, but rather decreased to almost undetectable levels during pregnancy.
  
  
  CONCLUSIONS
  Both the neutralizing and binding antibodies against ADAMTS13 decreased to almost undetectable levels after delivery in this patient, which can be caused by an immunological reset.
authors.affiliation: Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi City, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ogawa
authors.affiliation: Department of Blood Transfusion Medicine, Nara Medical University, Kashihara City, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Obstetrics and Gynecology, Gunma University Graduate School of Medicine, Maebashi City, Japan.
authors.forename: Hisanobu
authors.initials: H
authors.lastname: Sadakata
authors.affiliation: Department of Blood Transfusion Medicine, Nara Medical University, Kashihara City, Japan.
authors.forename: Ayami
authors.initials: A
authors.lastname: Isonishi
authors.affiliation: Department of Blood Transfusion Medicine, Nara Medical University, Kashihara City, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kato
authors.affiliation: Department of Medicine and Clinical Science, Gunma University Graduate School of Medicine, Maebashi City, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Nojima
authors.affiliation: Department of Blood Transfusion Medicine, Nara Medical University, Kashihara City, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fujimura
keywords: ADAMTS13 antibody; ADAMTS13 gene mutation; Fresh frozen plasma; Pregnancy; Upshaw-Schulman syndrome