Identification of 123 previously unreported mutations in the F8 gene of Iranian patients with haemophilia A.

In Haemophilia A (HA), the deficiency in coagulation factor VIII is caused by mutations in the F8 gene. In the past, HA carrier detection in Iran used to be carried out by tracking polymorphic DNA markers - a technical strategy with poor efficacy and accuracy. For some 10 years, however, mutations have been identified by direct DNA sequencing at the Iranian Comprehensive Haemophilia Care Centre (ICHCC), resulting in the detection of 580 different mutations and accurate carrier detection. The aim of this study was to characterize and report the unreported mutations not recorded in the F8 HAMSTeRS database and HGMD, which we have detected amongst all the mutations hitherto identified. After excluding introns 1 and 22 inversions, direct DNA sequencing was used to detect mutations among our patients. These were then confirmed in another affected relative or obligate carrier. Severe cases of HA, where no mutation could be identified, were further investigated by the MLPA method. The new, unreported mutations identified include: 51 missense, 15 nonsense, 45 frame-shifts, 11 splice-site, 1 duplications. We report a large spectrum of mutations identified in the course of the past 10 years at the ICHCC, which offers this service to all patients from regions throughout Iran. Aside from the common introns 1 and 22 inversions, this work demonstrates a high degree of heterogeneity in F8 mutations. The establishment of a comprehensive Iranian HA database will improve the care and genetic counselling of Iranian HA families.

Clinical outcome of interferon and ribavirin combination treatment in hepatitis C virus infected patients with congenital bleeding disorders in Iran.

Hepatitis C virus (HCV) infection is a major cause of morbidity and mortality in patients with inherited bleeding disorders. The results of interferon and ribavirin combination therapy have been reported in a limited number of clinical trials on these patients. Peginterferon is a costly treatment. Conventional interferon and ribavirin therapy is still the main available and affordable antiviral therapy in some countries. The goal of this study was to assess the effectiveness and safety of interferon alfa-2b plus ribavirin in HIV seronegative, non-alcoholic, non-cirrhotic, naïve subjects with congenital coagulopathy. Between May 2003 and August 2007, 103 haemophiliacs were treated consecutively with standard inclusion and exclusion criteria, with interferon alfa-2b (PDferon B) 3MIU three times a week subcutaneously plus ribavirin, for 24-48 weeks, with appropriate dose adjustments. They were all scheduled to have serial visits and laboratory tests. Among 7(6.8%) female and 96(93.2%) male haemophiliacs, 11(10.68%) cases did not complete the study because of psychological side effects. With intent-to-treat analysis, end-of-treatment response was 63.1%, and sustained virological response (SVR) was 56.3%. There was a significant correlation between SVR and genotype, baseline HCV viral load, rapid virological response, early virological response and BMI. A decrease in the haemoglobin level of two patients required ribavirin dose reduction. One developed thrombocytopenia at the end of treatment, but none had neutropenia. Hypothyroidism was observed in two patients. Interferon plus ribavirin combination therapy in HCV-infected haemophilic patients is well tolerated and treatment outcomes appear to be similar to those seen in the general population.

Factor VIII genotype and inhibitor development in patients with haemophilia A: highest risk in patients with splice site mutations.

The appearance of inhibitory antibodies against factor VIII (FVIII) is the most severe and costly complication of replacement therapy in patients with haemophilia A (HA). To determine the relationship between FVIII genotype and inhibitor development, baseline FVIII activity, genotype and inhibitor development were reviewed in 1104 patients with HA. In patients with severe HA, splicing errors present the highest frequency of inhibitors, ahead of inversion of intron 1 and of intron 22, nonsense mutations and large deletions. The lowest inhibitor frequency in severe HA is found in patients with missense mutations and small deletions/insertions. Subanalyses indicate that nonsense mutations and small deletions/insertions leading to a frameshift in the light chain are associated with a significant higher risk of inhibitor formation than similar mutations occurring in the heavy chain (27% vs. 14%). These mutation types also have a higher frequency of inhibitors when occurring in exons 23-26, where a second FVIII transcript originates, compared with similar mutations in exons 1-22 (28% vs. 17%). These results suggest that complete absence of FVIII because of null mutations, including splice site mutations, or the absence of a second transcript result in an increased risk of inhibitor development.

Seven novel point mutations in the F11 gene in Iranian FXI-deficient patients.

Factor XI (FXI) deficiency disorder is caused by defects in the F11 gene. The affected patients may suffer unexpected and major bleeding after trauma. Hence, the aim of this study was to identify the mutations underlying FXI deficiency in Iranian patients. The genetic basis of FXI deficiency was investigated in nine Iranian patients from unrelated families using conformation-sensitive gel electrophoresis (CSGE) and direct sequencing. Nine different mutations were detected among which seven changes were not previously reported. Among the novel mutations, one was a point mutation that interfered with normal splicing of the mRNA; the other six changes were missense mutations that resulted in amino acid substitutions. Five mutations out of nine were heterozygous and were found in moderately affected patients, whereas the other four changes were homozygous among severely affected patients.

Defect of heparin binding in plasma and recombinant von Willebrand factor with type 2 von Willebrand disease mutations.

The aim of our study was to characterise heparin-binding properties of mutated von Willebrand factor (VWF) in 24 patients plasmas with type 2 von Willebrand disease (VWD). and in 15 recombinant VWF (rVWF) with the corresponding mutations. Binding of mutated rVWF or plasma VWF was compared to that of WT-rVWF or normal pool plasma VWF. Four mutations, at positions C509, V551, R552 and R611 lead to significantly decreased binding to heparin in both plasma and rVWF. Interestingly, whereas these four residues are distant in the primary structure of VWF-A1domain, they are close to each other in its three-dimensional structure. Structural analysis suggested how folding problems and destabilisation due to these mutations could induce reorganisation of surface regions involved in heparin binding. In contrast, no heparin-binding defect was found associated with different type 2 VWF mutants, at positions G561, E596, I662, R543, R545, V553, R578 or L697.

Effect of recombinant von Willebrand factor reproducing type 2B or type 2M mutations on shear-induced platelet aggregation.

The aim was to better understand the function of von Willebrand factor (vWF) A1 domain in shear-induced platelet aggregation (SIPA), at low (200) and high shear rate (4000 seconds(-1)) generated by a Couette viscometer. We report on 9 fully multimerized recombinant vWFs (rvWFs) expressing type 2M or type 2B von Willebrand disease (vWD) mutations, characterized respectively by a decreased or increased binding of vWF to GPIb in the presence of ristocetin. We expressed 4 type 2M (-G561A, -E596K, -R611H, and -I662F) and 5 type 2B (rvWF-M540MM, -V551F, -V553M, -R578Q, and -L697V). SIPA was strongly impaired in all type 2M rvWFs at 200 and 4000 seconds(-1). Decreased aggregation was correlated with ristocetin binding to platelets. In contrast, a distinct effect of botrocetin was observed, since type 2M rvWFs (-G561A, -E596K, and -I662F) were able to bind to platelets to the same extent as wild type rvWF (rvWF-WT). Interestingly, SIPA at 200 and 4000 seconds(-1) confirmed the gain-of-function phenotype of the 5 type 2B rvWFs. Our data indicated a consistent increase of SIPA at both low and high shear rates, reaching 95% of total platelets, whereas SIPA did not exceed 40% in the presence of rvWF-WT. Aggregation was completely inhibited by monoclonal antibody 6D1 directed to GPIb, underlining the importance of vWF-GPIb interaction in type 2B rvWF. Impaired SIPA of type 2M rvWF could account for the hemorrhagic syndrome observed in type 2M vWD. Increased SIPA of type 2B rvWF could be responsible for unstable aggregates and explain the fluctuant thrombocytopenia of type 2B vWD. (Blood. 2000;95:3796-3803)

von Willebrand factor binding to heparin in various types of von Willebrand disease.

INTRODUCTION: The purpose was to study von Willebrand factor (vWF) binding to heparin in different types of von Willebrand disease (vWD). MATERIALS AND METHODS: Plasma samples from 92 patients were representative of most vWD subtypes as they included 13 type 1, ten type 2N, 27 type 2A, 23 type 2B, and 19 type 2M patients. We selected assay conditions suitable for the screening of plasma vWF concentrations as low as 15 U/dl vWF:Ag. We determined the range of vWF concentrations in plasma where the percentage of (125)I-MAb/vWF complexes bound to heparin-agarose beads was constant. This range of dilution allowed circumvention of potential competition by other plasma heparin-binding proteins. RESULTS: The multimeric composition of vWF had hardly any influence on the ability of vWF to bind to heparin. Results were expressed as the ratio of heparin-binding capacity of patients' plasma to that of normal pool plasma. We found a ratio of 0.99+/-0.004 (mean+/-s.e.m.) for 23 normal individual donors. Furthermore, when comparing the mean values of plasma vWF-heparin binding ratios by ANOVA F-test in the six groups (one normal and five vWD), we found significant differences between them (P<0.0001). Pairwise comparison of multiples by the Scheffe's test indicated that the mean values of ratios in type 2A on the one hand and type 2M on the other, were significantly lower than in normal plasma, type 2N, type 2B and type 1. CONCLUSION: Our data suggest a relationship between the ability of vWF to bind to heparin and to the platelet GPIb receptor, since type 2B and 2N patients have an increased or normal ability to bind to GPIb whereas type 2A and 2M patients have an impaired interaction with that receptor.

Modulation by heparin of the interaction of the A1 domain of Von Willebrand factor with glycoprotein Ib.

The conformation of the A1 domain of von Willebrand factor (vWF) is a critical determinant of its interaction with the glycoprotein (GP) Ib/V/IX complex. To better define the regulatory mechanisms of vWF A1 domain binding to the GPIb/V/IX complex, we studied vWF-dependent aggregation properties of a cell line overexpressing the GPIbalpha, GPIbbeta, and GPIX subunits (CHO-GPIbalphabeta/IX cells). We found that CHO-GPIbalphabeta/IX cell aggregation required the presence of both soluble vWF and ristocetin. Ristocetin-induced CHO-GPIbalphabeta/IX cell aggregation was completely inhibited by the recombinant VCL fragment of vWF that contains the A1 domain. Surprisingly, the substitution of heparin for ristocetin resulted in the formation of CHO-GPIbalphabeta/IX cell aggregates. Using monoclonal antibodies blocking vWF interaction with GPIb/V/IX or mocarhagin, a venom metalloproteinase that removes the amino-terminal fragment of GPIbalpha extending from aa 1 to 282, we demonstrated that both ristocetin- and heparin-induced aggregations involved an interaction between the A1 domain of vWF and the GPIbalpha subunit of the GPIb/V/IX complex. The involvement of heparin in cell aggregation was also demonstrated after treatment of heparin with heparinase that abolished CHO-GPIbalphabeta/IX cell aggregation. These results indicated that heparin was able to induce vWF-dependent CHO-GPIbalphabeta/IX cell aggregation. In conclusion, we demonstrated that heparin is capable of positively modulating the vWF interaction with the GPIb/V/IX complex.

[Primary carcinoma of Stensen's duct. A case report]. / Carcinoma primitivo del dotto di Stenone. Presentazione di un caso.

The authors report a rare case of primitive carcinoma of Stensen's duct, pointing out the histological characteristics which enable the origin to be identified in the covering epithelium of the major salivary duct.

[Ductal carcinoma of the salivary glands. Case report]. / Il carcinoma duttale delle ghiandole salivari. Presentazione di un caso.

A rare case of carcinoma of the salivary gland ducts highlights potential clinical malignity and the need for adequate therapeutic action, aimed above all at preventing the onset of recurrences and metastasis, including cases which have been clearly differentiated histologically.