Summary We have previously reported that the 3363 inserted (Ins) C mutation in exon 6 of the protein C gene was present in four unrelated French patients and in four French Canadian families with type I protein C deficiency as well as in a large Vermont protein C deficient kindred of French Canadian origin. The present study was designed to investigate the likelihood of the existence of a founder effect for this mutation in protein C deficient individuals of French origin living in France, Québec and Vermont. In order to demonstrate a possible founder effect for the 3363 InsC mutation, we have previously constructed a high-resolution genetic map to locate several highly polymorphic markers close to the protein C locus. Thereafter, the markers D2S347, D2S2339, D2S383, D2S2271 and D2S2215 were genotyped in 117 heterozygotes from France (n = 7), Québec (n = 36) or Vermont (n = 74). The allelic frequency distribution of these five markers was also determined in fifty control French Canadian subjects and thirty-two unaffected members of the Vermont kindred with normal protein C levels and compared with their frequency in our cohort of heterozygotes. Our data suggest that patients from Québec and Vermont carry a common haplotype at the protein C locus. Moreover, in order to study the evolutionary history of the 3363 InsC mutation, we traced back the ascending genealogy of one proband in each of the families with this mutation. These results showed that the 3363 InsC mutation was most probably introduced in North America by a couple of French settlers who established themselves in 1669 on Isle d‘Orleans located near Québec City. All heterozygotes for the 3363 InsC mutation living in North America are related to these founders within 10 generations. Thus, these families afford a unique opportunity to evaluate the role of the protein C system in thrombophilia due to the high degree of linkage disequilibrium at the protein C gene, which in essence holds that variable more constant than in a more heterogeneous population.
To compare the sensitivity, specificity, and predictive values of compression ultrasonography (US) in postoperative orthopedic patients with those of (a) impedance plethysmography in postoperative patients and (b) compression US in symptomatic outpatients, the authors performed an investigator-blinded cohort study. One hundred thirty-four consecutive inpatients who had undergone elective knee-replacement surgery or surgery for a fractured hip and 65 consecutive outpatients with clinically suspected venous thrombosis who had undergone venography were evaluated. Compression US allowed detection of 11 of 21 (52.4%) proximal-vein thrombi but was insensitive to calf-vein thrombi in the orthopedic patients. Compression US had a significantly greater specificity and positive predictive value than impedance plethysmography for all thrombi in orthopedic patients; compression US also had greater sensitivity. The sensitivity of compression US for proximal-vein thrombi was significantly higher (92.1%) in symptomatic outpatients than in orthopedic patients. The authors conclude that compression US has significant advantages over impedance plethysmography in the detection of proximal-vein thrombi in patients who have undergone hip- or knee-replacement surgery.
Introduction Acquired haemophilia A (AHA) is a rare autoimmune bleeding disorder caused by neutralizing antibodies against factor VIII (FVIII). Despite significant initial morbidity and mortality, most patients achieve remission with immunosuppressive therapy. Aim Long‐term follow‐up data from the Quebec Reference Centre for Inhibitors (QRCI) were analysed to identify factors predictive of AHA relapse and the influence of relapse on survival. Methods Criteria used to define AHA were levels of FVIII <0.3 IU/mL and FVIII inhibitor titres ≥0.6 Bethesda Units (BU). Complete remission was defined as FVIII >0.5 IU/mL and/or FVIII inhibitor titres <0.6 BU while not on immunosuppression. Results Between 2000 and 2012, 111 subjects met the inclusion criteria and were followed for a median of 25.6 months. Ninety per cent of them reached remission on immunosuppression in a median time of 45 days. Fourteen patients presented one or more relapses in a median time of 13.4 months. Most relapse episodes were successfully treated. Associated lymphoproliferative syndromes (LPS) were predictive of relapse, whereas FVIII activity and inhibitor titres at initial diagnosis or immunosuppressive regimens were not. The overall survival (OS) was the same, with or without relapse. Conclusion Among the recognized potential risk factors for relapse, only LPS was statistically significant. The long‐term follow‐up of our patients also showed that late or multiple relapses may occur, but that relapse is not associated with a worse OS. Thus, long‐term follow‐up is important for optimal management of AHA.
Persons with inherited bleeding disorders are at a substantial risk of bleeding following dental procedures.To compare the outcomes and use of haemostatic treatment pre- and post-implementation of a standardized protocol for dental procedures at a Hemophilia Treatment Centre.We conducted a retrospective cohort study of outpatient and inpatient dental procedures and maxillofacial surgeries sustained by people with bleeding disorders treated at a comprehensive Hemophilia Treatment Centre (2013-2020), comparing patients' outcomes before and after the introduction of the protocol in 2018. The protocol, built using a multidisciplinary approach, suggested haemostatic treatment based on the invasiveness of the dental procedure and the proposed anaesthesia. Our primary outcome was the rate of procedural bleeding leading to medical or dental reintervention within 10 days. Secondary outcomes included the use of systemic haemostatic treatment and treatment-related adverse effects.Overall, 137 dental procedures in 95 patients (median age: 29 years; 78% males; 74% haemophilia, 14% von Willebrand disease, 12% other disorders) were included. Seventeen procedural bleedings were reported (12.4%). Procedural bleeding occurred in 14.8% and 8.9% of patients in the control and intervention groups (p = .304). No major bleeding occurred. Tranexamic acid was used more consistently after protocol implementation (72.8% vs. 89.3%, p = .019), while factor concentrates use decreased (65.4% vs. 44.6%, p = .016), and desmopressin use remained constant (46.4% vs. 32.1%, p = .100). No treatment-related adverse effects were reported.The use of a standardized protocol increased the use of tranexamic acid, with a nonstatistically significant reduction in procedural bleeding rate.
