Genetic variants of VWF gene in type 2 von Willebrand disease.

INTRODUCTION: von Willebrand disease (VWD) is the most common inherited bleeding disorder. Few studies have explored the molecular basis of type 2 VWD. AIM: This study aimed to identify variants associated with type 2 VWD. METHODS: We collected clinical and laboratory data, as well as response to desmopressin and bleeding assessment tool (BAT) score in patients diagnosed with type 2 VWD. We sequenced exons 17, 18, 20 and 28 of the VWF gene. RESULTS: We identified 19 different variants in 40 unrelated patients (47.5%). Most of the variants (84.2%) were found in exon 28. A total of 10/19 variants (52.6%) were identified as "likely causative" in 17/40 patients (42.5%), according to the ISTH-SSC and EAHAD VWF gene mutations databases. Nine variants were initially identified as potentially benign. However, through analyses in silico, four of these variants were reclassified as "likely pathogenic" (Ile1380Val, Asn1435Ser, Ser1486Leu and Tyr1584Cys). Response to desmopressin was associated with three variants: Met740Ile, Arg1597Gln and Tyr1584Cys. Major bleeding was associated with variants related to VWD subtypes 2B and 2M. CONCLUSION: In conclusion, we identified 19 variants, of which 14 are "likely pathogenic" and therefore associated with VWD. We suggest a possible association of pathogenic variants with major bleeding, response to desmopressin and BAT score ≥10, although this requires further confirmation.

Hydroxyurea increases plasma concentrations of microparticles and reduces coagulation activation and fibrinolysis in patients with sickle cell anemia.

Microparticles (MPs) are present in healthy subjects and their concentration increases in patients at high risk of thrombosis. We evaluated 10 patients with sickle cell anemia (SCA) treated with hydroxyurea (HU) and 13 SCA patients without this treatment. MP concentrations were determined by flow cytometry. Coagulation was evaluated using the thrombin-antithrombin complex (TAT) and D-dimers. Total MP concentrations were increased in the HU-treated group (265 × 10(6)/ml vs. 67.45 × 10(6)/ml; p = 0.0026), as well as MPs derived from RBC (67.83 × 10(6)/ml vs. 26.31 × 10(6)/ml; p = 0.05), monocytes (51.31 × 10(6)/ml vs. 9.03 × 10(6)/ml; p = 0.0084), monocytes with tissue factor (TF) expression (2.27 × 10(6)/ml vs. 0.27 × 10(6)/ml; p = 0.0058), endothelium (49.42 × 10(6)/ml vs. 7.23 × 10(6)/ml; p = 0.007) and endothelium with TF (1.42 × 10(6)/ml vs. 0.26 × 10(6)/ml; p = 0.0043). Furthermore, the concentrations of TAT (7.56 vs. 10.98 µg/l; p = 0.014) and D-dimers (0.65 vs. 1.29 µg/ml; p = 0.007) were reduced with HU. The MP elevation may suggest a direct cytotoxic effect of HU. Another explanation is a cell surface increase secondary to a megaloblastic process, resulting in increased vesicle release. In our opinion, the known benefits of HU on SCA patients, along with the reduction in coagulation activation, surpass its potential detrimental effect on MPs. Future studies should elucidate the role of MPs and demonstrate their significance in different contexts.

Therapeutic leukapheresis in patients with leukostasis secondary to acute myelogenous leukemia.

Leukostasis is a relatively uncommon but potentially catastrophic complication of acute myelogenous leukemia (AML). Prompt leukoreduction is considered imperative to reduce the high mortality rate in this condition. Leukapheresis, usually associated with chemotherapy, is an established approach to diminish blast cell counts. We report a single center experience in managing leukostasis with leukapheresis. Fifteen patients with leukostasis of 187 patients with AML (8.02%) followed at our institution were treated with leukapheresis associated with chemotherapy. The procedures were scheduled to be performed on a daily basis until clinical improvement was achieved and WBC counts were significantly reduced. Overall and early mortalities, defined as that occurred in the first 7 days from diagnosis, were reported. A high proportion of our patients with leukostasis (46.66%) had a monocytic subtype AML (M4/M5, according to French-American-British classification). The median overall survival was 10 days, despite a significant WBC reduction after the first apheresis procedure (from 200.7 × 109/L to 150.3 × 109/L). Almost half of patients (7/15) had an early death. Therapeutic leukapheresis, associated or not to chemotherapy, is an effective approach to reduce WBC counts in patients with AML and leukostasis; however, this therapeutic procedure does not appear to change significantly the sombre prognosis observed in the majority of patients with this complication. Other forms of treatment must be found to reduce the high mortality rate related to leukostasis.

Yttrium-90 radiosynovectomy in knees and ankles (25 joints in 22 hemophilic patients). Short-term results.

INTRODUCTION: The radiosynovectomy (RS) is one treatment option for recurrent hemarthrosis in patients with hemophilia (PWH). A prospective cohort study was designed to evaluate the effects of the RS on the synovial membrane volume in the ankles and knees of PWH and patient characteristics related to the RS outcome. METHODS: In a one-year follow-up, 25 joints of 22 PWH who presented 3 bleeds or more in the same joint over the last 6 months (target joints) were subjected to the RS. Two groups were compared: those who retained target joints following the RS and those who did not (less than 3 bleeds/6 months after the RS). The groups were analyzed according to age, hemophilia type/severity, joint, body mass index (BMI), inhibitor and Hemophilia Joint Health Score 2.1 (HJHS). The magnetic resonance images (MRI) of six ankles and six knees were acquired prior to, and 6 months after, the RS. The synovial membrane volume and arthropathy MRI scale were accessed and volumes were compared and correlated with the Yttrium-90 dose injected. RESULTS: Patients with a mean age of 12 years and a mean HJHS of 6.7 (p < 0.05) retained target joints after the RS. The inhibitor, joint, type/severity of disease and BMI showed no significant differences between groups. The synovial membrane volume had a significant reduction after the RS (p = 0.03), but no correlation with the Yttrium-90 dose. In proportion to the synovial membrane volume, doses injected to the ankles were larger than those injected to the knees. CONCLUSION: The synovial membrane volume is reduced after the RS, regardless of the effective 90Y dose.