B. Baran

Phenotype-genotype correlation in eight Polish patients with inherited Factor XIII deficiency: identification of three novel mutations

Summary. Inherited factor XIII (FXIII) deficiency is known as one of the most rare blood coagulation disorder in humans. In the present study, phenotype and genotype of eight FXIII deficient Polish patients from five unrelated families were compared. The patients presented with a severe phenotype demonstrated by a high incidence of intracerebral haemorrhages (seven of eight patients), haemarthrosis (six patients) and bleeding due to trauma (five patients). Introduction of regular substitution with FXIII concentrate prevented spontaneous bleeding in seven patients. In all patients, mutations within the F13A gene have been identified revealing four missense mutations (Arg77Cys, Arg260Cys, Ala378Pro, Gly420Ser), one nonsense mutation (Arg661X), one splice site mutation (IVS5‐1 G>A) and one small deletion (c.499–512del). One homozygous large deletion involving exon 15 was detected by failure of PCR product. The corresponding mutations resulted in severely reduced FXIII activity and FXIII A‐subunit antigen concentration, while FXIII B‐subunit antigen remained normal or mildly decreased. Structural analysis demonstrated that the novel Ala378Pro mutation may cause a disruption of the FXIII catalytic triad leading to a non‐functional protein which presumably undergoes premature degradation. In conclusion, the severe phenotype with high incidence of intracranial bleeding and haemarthrosis was in accordance with laboratory findings on FXIII and with severe molecular defects of the F13A gene.

The first case of combined coagulation factor V and coagulation factor VIII deficiency in Poland due to a novel p.Tyr135Asn missense mutation in the MCFD2 gene.

Congenital combined coagulation factor V and coagulation factor VIII deficiency (F5F8D) is a rare bleeding disorder due to mutations in the LMAN1 or MCFD2 genes. Here we report the first Polish family with F5F8 deficiency due to a mutation in the MCFD2 gene. The proposita suffered from mild bleeding including epistaxis, menorrhagia, bleeding after dental extraction, and bruising after minor traumas. The F5F8 deficiency was diagnosed due to an excessive postpartum bleeding at the age of 31. Analysis of further family members revealed a second affected individual. Sequencing of the MCFD2 gene and its flanking regions in both patients demonstrated a novel homozygous missense mutation within the second elongation factor hand domain resulting in a substitution of tyrosine by asparagine at amino acid position 135 (p.Tyr135Asn). This variant represents the third missense mutation found in the MCFD2 gene and most likely disrupts the MCFD2–LMAN1 interaction, thus leading to the disease phenotype.

Activated prothrombin complex concentrate in combination with tranexamic acid: a single centre experience for the treatment of mucosal bleeding and dental extraction in haemophilia patients with inhibitors.

Patients with haemophilia A or B are treated with factor VIII and factor IX concentrates, respectively, and those patients who have developed antibodies (inhibitors) are further treated primarily with either recombinant activated factor VII (rFVIIa) or plasmaderived activated prothrombin complex concentrate (aPCC)/factor VIII inhibitor bypassing activity (FEIBA; Baxter, Baxalta, Vienna, Austria) [1]. These bypassing agents are indicated for patients with high titre inhibitors [>5 Bethesda units (BU) mL ] who do not respond to coagulation factor replacement therapy infusion [2,3]. Although rFVIIa and aPCC have been established as safe and effective therapies for treating bleeding episodes in haemophilia patients with inhibitors, the efficacy of either bypassing agent can vary and neither agent is uniquely effective for all patients in all situations [4]. Preventing bleeding in patients with haemophilia undergoing surgery remains a significant challenge and both major and minor surgeries have been performed in haemophilia patients with inhibitors [5,6]. Both rFVIIa and aPCC are used to prevent perioperative and procedural bleeding with satisfactory results [7]. A recent prospective study of 35 surgical patients confirms a large body of evidence demonstrating that aPCC can be safely and effectively used as perioperative haemostatic therapy when performing surgical procedures in haemophilia patients with inhibitors [8,9]. Recent guidelines define optimal doses and schedule for rFVIIa and aPCC [9]. Indeed, consensus recommendations have been developed to provide a standardized approach for dosing and monitoring of aPCC in haemophilia A patients with inhibitors undergoing elective orthopaedic and non-orthopaedic surgery [10]. Tranexamic acid (TXA) is a synthetic anti-fibrinolytic agent that competitively blocks the lysine-binding sites for plasminogen, plasmin and tissue plasminogen activator, thus affecting a delay in fibrinolysis and clot degradation. The results of concomitant use of TXA with bypass therapy as haemostatic support during surgery has been promising in both surgical [5] and non-surgical settings [11]. TXA increases clot stability and is used concomitantly with coagulation factor replacement therapy to improve haemostasis in haemophilia patients with inhibitors in many countries throughout Europe [12]. Since aPCC increases thrombin generation and TXA inhibits fibrinolysis [13], combining aPCC and TXA has been limited due to safety concerns over the possibilities of increased risk of thrombotic events and disseminated intravascular coagulation (DIC). Few studies have evaluated this combination for the management of bleeding episodes and in preventing haemorrhage during surgery or dental extraction; however, this combination has been shown to improve clot stability without further increasing thrombin generation, indicating a synergistic effect, but not at the cost of higher thrombogenicity [13]. In our centre, concomitant use of aPCC and TXA is a standard of care in patients with inherited bleeding disorders who suffer mucosal bleeds or undergo invasive procedures on mucosa membranes (e.g. dental extraction). Combination use rather than aPCC given alone is based on our past experience when access to bypassing agents in Poland was limited, and combination therapy of lower doses of aPCC with TXA (given orally or intravenously) proved effective (data not published). The current article presents our single centre experience with the use of TXA in combination with aPCC (FEIBA) for the treatment of mucous membrane haemorrhages or perioperative prevention of bleeding episodes in haemophilia patients with inhibitors who underwent dental extractions. The safety and efficacy of TXA as adjunctive therapy to aPCC was retrospectively evaluated by file review of patients with inhibitors who underwent dental invasive procedures or were treated for mucous membrane Correspondence: Jerzy Windyga, MD, PhD, Department of Disorders of Hemostasis and Internal Medicine, Institute of Hematology and Transfusion Medicine, 14 I. Gandhi Str., 02776 Warsaw, Poland. Tel.: +48 22 3496158; fax: +48 22 3496159; e-mail: jwindyga@ihit.waw.pl

Nabyta choroba von Willebranda (AVWS) przyczyną skazy krwotocznej u chorej z wywiadem niedoczynności tarczycy i niewydolnością nerek

B. Baran *, E. Odnoczko , E. Stefanska-Windyga , K. Bykowska , J. Oldenburg , J. Windyga 1 Zaklad Hemostazy i Chorob Metabolicznych, Instytut Hematologii i Transfuzjologii, Warszawa, Polska Poradnia Zaburzen Hemostazy, Instytut Hematologii i Transfuzjologii, Warszawa, Polska 3 Instytut Hematologii Eksperymentalnej i Transfuzjologii, Bonn, Niemcy *Autor prezentujący i do korespondencji. Adres email: bbaran@ihit.waw.pl

Analiza genetyczna w diagnostyce typu 2N choroby von Willebranda – pierwsze doświadczenia

B. Baran *, E. Odnoczko , E. Stefanska-Windyga , K. Bykowska , J. Oldenburg , J. Windyga 1 Zaklad Hemostazy i Chorob Metabolicznych, Instytut Hematologii i Transfuzjologii, Warszawa, Polska Poradnia Zaburzen Hemostazy, Instytut Hematologii i Transfuzjologii, Warszawa, Polska 3 Instytut Hematologii Eksperymentalnej i Transfuzjologii, Bonn, Niemcy *Autor prezentujący i do korespondencji. Adres email: bbaran@ihit.waw.pl