Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): comprehensive genetic analysis by next-generation sequencing of 480 patients

Molecular diagnosis of patients with von Willebrand disease is pending in most populations due to the complexity and high cost of conventional molecular analyses. The need for molecular and clinical characterization of von Willebrand disease in Spain prompted the creation of a multicenter project (PCM-EVW-ES) that resulted in the largest prospective cohort study of patients with all types of von Willebrand disease. Molecular analysis of relevant regions of the VWF, including intronic and promoter regions, was achieved in the 556 individuals recruited via the development of a simple, innovative, relatively low-cost protocol based on microfluidic technology and next-generation sequencing. A total of 704 variants (237 different) were identified along VWF, 155 of which had not been previously recorded in the international mutation database. The potential pathogenic effect of these variants was assessed by in silico analysis. Furthermore, four short tandem repeats were analyzed in order to evaluate the ancestral origin of recurrent mutations. The outcome of genetic analysis allowed for the reclassification of 110 patients, identification of 37 asymptomatic carriers (important for genetic counseling) and re-inclusion of 43 patients previously excluded by phenotyping results. In total, 480 patients were definitively diagnosed. Candidate mutations were identified in all patients except 13 type 1 von Willebrand disease, yielding a high genotype-phenotype correlation. Our data reinforce the capital importance and usefulness of genetics in von Willebrand disease diagnostics. The progressive implementation of molecular study as the first-line test for routine diagnosis of this condition will lead to increasingly more personalized and effective care for this patient population.

Molecular and clinical profile of von Willebrand disease in Spain (PCM-EVW-ES): Proposal for a new diagnostic paradigm

The diagnosis of von Willebrand disease (VWD) remains difficult in a significant proportion of patients. A Spanish multicentre study investigated a cohort of 556 patients from 330 families who were analysed centrally. VWD was confirmed in 480. Next generation sequencing (NGS) of the whole coding VWF was carried out in all recruited patients, compared with the phenotype, and a final diagnosis established. A total of 238 different VWF mutations were found, 154 were not included in the Leiden Open Variation Database (LOVD). Of the patients, 463 were found to have VWF mutation/s. A good phenotypic/genotypic association was estimated in 96.5% of the patients. One hundred seventy-four patients had two or more mutations. Occasionally a predominant phenotype masked the presence of a second abnormality. One hundred sixteen patients presented with mutations that had previously been associated with increased von Willebrand factor (VWF) clearance. RIPA unavailability, central phenotypic results disagreement and difficult distinction between severe type 1 and type 3 VWD prevented a clear diagnosis in 70 patients. The NGS study facilitated an appropriate classification in 63 of them. The remaining seven patients presented with a VWF novel mutation pending further investigation. In five patients with a type 3 and two with a type 2A or 2B phenotype with no mutation, an acquired von Willebrand syndrome (AVWS) was suspected/confirmed. These data seem to support NGS as a first line efficient and faster paradigm in VWD diagnosis.

[Von Willebrand disease: characteristics and response to desmopressin. Study of 103 cases]

BACKGROUND

To describe the main characteristics and response to desmopressin infusion in 103 patients suffering from von Willebrand disease (vWD).

PATIENTS AND METHODS

The criteria for diagnosis were (except for type 2N) the coexistence of von Willebrand factor ristocetin cofactor (vWF:RCo) activity < 50 U/dl with bleeding disease or one of the following data: von Willebrand factor antigen (vWF:Ag) activity < 50 U/dl, factor VIII (FVIII) activity < 50 U/dl or the existence of a increased bleeding time (BT). Multimeric studies of vWF were performed in 51 cases and ristocetin induced platelet aggregation (RIPA) was also performed.

RESULTS

Spontaneous bleeding was found in 36 patients, while in 18 cases the diagnosis was done after surgical bleeding. Thirteen patients (6 presenting with mild bleeding) were studied for abnormalities in the routine preanestesic tests. Other 22 patients were diagnosed with vWD by familial studies. There were 3 patients with type 2B, 1 case with type 2N and other patient with type 3. BT was found increased in 26 out of 58 patients. The activities of vWF:CoR and vWF:Ag were 38.4 (9.4) U/dl and 45.8 (23.2) U/dl, respectively, while the activity of FVIII was 49.9 (20.8) U/dl. Prophylactic DDAVP (desmopressin) was infused in 32 patients. After 1 h, basal activities of vWF:CoR and vWF:Ag were increased by 3.1 (3.2) and 3.4 (3.1) times, respectively, and maintained for 3 h. FVIII activity increased 3.6 (2.3) times the basal levels decreasing after 3 h (2.9 [2.1]; p < 0.01). The BT was corrected in 8 out of ten patients.

CONCLUSIONS

vWD is a major cause of surgical bleeding. Preanestesic anamnesis and coagulation tests can be useful to identify vWD. Many patients with vWD have normal BT. A failure in the response to desmopressin infusion is unusual.

[Checking oral anticoagulation in capillary blood]

PURPOSE

To check out the reproducibility and costs of prothrombin time (PT) determination as a control of oral anticoagulant therapy (OAT) in plasma and capillary blood.

PATIENTS AND METHODS

The study was carried out in two phases: along two years, 1,700 patients with OAT were controlled, 700 of them in the hospital outpatient clinic. In 149 patients INR was simultaneously determined in both capillary and venous blood. The 700 patients receiving acenocoumarin who had been controlled in 1991 according to the conventional plasma-sample fashion, were controlled in the second year (i.e., 1992) by means of capillary blood testing, a comparison of the costs of each method and the need for anticoagulant drugs being undertaken. Venous blood PT was assessed with reagent thromboplastin (Tromborel S) in an Electra-1000 (MLA) system. An automated Trombotrack system was used for the capillary blood tests using Thrombotest as current procedure. The results were expressed as INR in both methods. The statistical evaluation of the results was carried out by means of Student's t, variance analysis, and correlation study.

RESULTS

No significant differences were found in the anticoagulation intervals attained from venous or capillary blood samples. No significant differences were seen in 87 patients on whom the test was repeated in two samples drawn from a single capillary puncture. The weekly OAT doses of 30 patients along six months were analysed. The need for anticoagulant drugs was similar (17.4 vs 17.2 mg/patient/week). The mean INR in 1991 was 2.82 and the mean drug-need was 15.24 mg/week, whereas in 1992 the mean INR was 2.86 and the need for anticoagulant was 15.49 mg/week. The costs of the conventional method were 103.6 Pta, this being 70 Pta for capillary blood, which means a 32% savings.

CONCLUSIONS

OAT control by means of PT performed on capillary blood must be considered a substitutive method for the venous blood assay due to its efficacy, simplicity and lower costs.

[Tetanus in adults: mortality. Study in 130 cases]

Out of the 557 cases of tetanus in adult patients seen in our institution over 61 years, we have selected for analysis the 130 patients who where admitted to our service since its creation in 1968. We have found a trend toward older patient age in recent years. The age distribution showed a bimodal curve which was maintained in the different periods and was due, in the last one to the population of parenteral drug abusers. In the last 20 years there has been an increase in severe forms (p less than 0.001). The mortality was statistically associated with clinical severity (p less than 0.001) and with the surgical portal of entry (p less than 0.05). The development of intensive care reduced the mortality rate from 58.3% in the period before ICU to 24.6% in the 130 patients cared for since the service was created (p less than 0.001). In the last 10 years, the mortality rate of 41 patients was 9.7%. The most common cause of death was cardiac arrest (68.7%). Superinfection was the second cause (25%). The use of beta-blockers in patients with severe tetanus, with significant autonomic abnormalities, reduced the mortality from 72.7% to 14.8% (p less than 0.001). The mortality of superinfection has been maintained, without statistically significant changes.

[Studies of aggregation using pairs of agonists in platelet concentrates stored for 5 days. Influence of autologous fresh plasma]

Aggregation was studied with synergistic agents on platelets stored for 5 days. Fixed concentrations of agonist agents, capable of inducing maximum response upon platelet concentrate (PC) preparations were used, and the results were compared with those achieved from samples previously incubated in fresh autologous plasma. Platelet aggregation on day 0 ranged between 77 +/- 3% with the combination epinephrine/ADP and 72 +/- 7% with collagen/ADP, these figures decreasing by the fifth day to 14 +/- 5% and 10 +/- 4%, respectively. The other paired aggregation agents were epinephrine/collagen and arachidonic acid (AA)/ADP; with these agents, similar values were attained on day 0, along with an analogous derangement of the response by the fifth day. With the last combination, the aggregation value attained on days 3 was 14 +/- 10% in experiments with the PC plasma, as opposed to 49 +/- 15% in assays with fresh plasma (p less than 0.001). Such difference persisted on day 5 and was thought to be due to competence of the high concentration of fatty acids generated in the PC plasma by AA. No differences induced by fresh plasma on the other agonist combinations were detected. These results suggest that some derangement of platelet function, conditioned by nonreversible alterations, and measured by paired agonist aggregation, may derive from storage.

[Measurement of phospholipids in erythrocytes, plasma and platelets in a patient with hereditary spherocytosis]

The amount and distribution of phospholipids (PLs) were studied in erythrocytes, plasma and platelets of one patient with hereditary spherocytosis (HS). Phosphatidylethanolamine (PE) was always decreased. Total PLs amount was remarkably reduced in erythrocytes but normal in platelets. Since platelets do not contain those proteins which have been implicated in the red cell abnormalities of patients with HS, our findings reinforce the theory that a defective protein-lipid interaction causes the abnormal lipid loss in the erythrocytes of these patients.