Laboratory Diagnosis of von Willebrand Disease Type 1/2E (2A Subtype IIE), Type 1 Vicenza and Mild Type 1 Caused by Mutations in the D3, D4, B1–B3 and C1–C2 Domains of the von Willebrand Factor Gene

Abstract

Autosomal dominant von Willebrand disease (VWD) type 1/2E is a quantitative/qualitative defect in the von Willebrand factor (VWF) caused by heterozygous cysteine and non-cysteine mutations in the D3 domain of the VWF gene and results in a secretion-multimerization-clearance defect in mutant VWF with the loss of large VWF multimers not due to proteolysis. The multimers of patients with dominant VWD type 1/2E due to mutations in the D3 domain show an aberrant triplet structure with lack of outer bands but with pronounced inner bands of the triplet structure combined with a relative decrease in large multimers reflecting heterozygosity for multimerization defects. There is a good response to desmopressin (DDAVP) followed by rapid clearance of VWF:antigen (Ag), factor VIII coagulant activity (FVIII:C) and VWF:ristocetin cofactor activity (RCo) as the main cause of VWD type 1 or 2 with typical 2E multimeric pattern (VWD type 1/2E). Cysteine mutations in the D3 domains (C1130, C1149 and C1190) show pronounced features of VWD 1/2E with the relative loss of large and relative increase in small VWF multimers with abnormal triplet structure in heterozygotes. Such abnormalities are less pronounced in patients with a milder form of VWD type 1 due to non-cysteine mutations W1144G, T1156M and W1120S in the D3 domain. VWD type 1 Vicenza is caused by the R1205H mutation in the D3 domain and characterized by equally low levels of FVIII:C, VWF:Ag and VWF:RCo. The response to DDAVP in VWD Vicenza is good for FVIII:C, VWF:Ag and VWF:RCo, which is followed by a rapid clearance in less than a few hours of FVIII:C and VWF parameters. The ratios for FVIII:C/VWF:Ag, VWF:RCo/Ag and VWF:CB/Ag remain normal before and after DDAVP indicating that VWD Vicenza clearly differs from VWD type 1, 1/2E and 2M. A new set of missense mutations in D4, B1–B3 and C1–C2 domains has been discovered as the cause of a mild VWD type 1 secretion defect with normal VWF multimers or smeary VWF multimeric pattern. Cysteine mutations in exons 38, 40, 42 and 43 (D4, B1–B3 and C1 domain), show smeary patterns (either smf or sm), with the presence of large VWF multimers and a laboratory phenotype of mild VWD type 1 with variable penetrance of bleeding manifestations. Recent studies showed that the ratio of VWF propeptide (pp) to VWF:Ag can be used to predict a shorter than normal half-life for VWF:Ag. There is a strong inverse correlation between rapid clearance of VWF:Ag after DDAVP and increased VWFpp/Ag ratios >10 in VWD type 1 Vicenza, and >2 in VWD type 1/2E but normal or slightly increased (1–<2) VWFpp/Ag ratios in mild-type VWD due to nonsense or missense mutations in the D1, D2, D4, B and C domains.

Genetic determinants of plasma von Willebrand factor antigen levels: a target gene SNP and haplotype analysis of ARIC cohort

“…39 They also impact the ratio of VWF propeptide to mature VWF, which in turn affects the clearance of VWF in the circulation. 40 The D3 domain is important in VWF multimerization, which could impact VWF tertiary structure and ultimately circulating levels of VWF and its clearance. 39 It is also interesting to note that the rate of VWF clearance is found to be accelerated in patients with VWD Vicenza, which often have mutations, including intronic, in the D domains [41][42][43] (we did not find positive SNPs in the exon encoding D4 and flanking intronic sequence).…”

Qualitative and quantitative modifications of von Willebrand factor in patients with essential thrombocythemia and controlled platelet count

“…Data were also analyzed according to the blood groups and, consistently with VWF:Ag, VWF:act was %40% higher in 'non-0' vs. '0' healthy controls (Fig. 1B), while blood groups did not [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] Values are expressed as medians, and IQR is reported in brackets. *P < 0.001 vs. controls; **P < 0.001 vs.…”

Laboratory Diagnosis and Molecular Basis of Mild von Willebrand Disease Type 1

“…The concept in figures 6 and 7 points to the wide heterogeneity of mild VWD type 1 as a heterozygous disorder with variable penetrance of bleeding manifestations but clearly distinct from the autosomal dominant VWD phenotypes VWD type 1 Vicenza, type 1 clearance defect with 2E multimeric pattern (1C/2E) or 2M [27,28,29]. The DDAVP-induced response curves of FVIII:C, VWF:Ag, VWF:RCo and VWF:CB will clearly reveal typical diagnostic features to distinguish mild VWD type 1 with normal VWF function, clearance and multimers from those with abnormal multimers, clearance defects and/or VWF:RCo and RIPA defects in each of VWD type Vicenza, type 1C/2E, 2M, type 1 with smeary VWF multimers (1sm) or 1sm with faster moving band (1smf) [30,31,32,33,34].…”

“…The mutations in exon 26, D3 domain, R1130R/G/F, W1144G, Y1146C and C1190R, in figure 7 usually present with a laboratory phenotype of dominant VWD 1 but have abnormal VWF multimers with typical features of VWD 2E [30]. In the study by Gadisseur et al [27], this entity was classified as dominant VWD type 1/2E. Patients with dominant VWD type 1/2E due to missense mutations in the D3 domain are characterized by a multimerization defect and the secreted heterozygous mutant-normal VWF after DDAVP is rapidly cleared, a phenomenon very well known for many years and most prominent in VWD type 1 Vicenza, R1205H [34].…”

“…The group with abnormal multimers of heterozygous mutations in the D4, B1–B3, C1–C2 and cysteine knot domains (V1822G, L2207P, C2257S, C2304Y, C2362F, G2441C, R2464C, C2477Y, C2477S and Q2520P) has mild/moderate VWD type 1, and usually smeary pattern or smeary pattern with faster moving bands indicating abnormal VWF multimers discovered using low- and medium-resolution agarose gel [38,39,40]. As described by Gadisseur et al [27], careful phenotyping of the missense mutations in the D4, B1–B3 and C1–C2 domains is warranted and has been performed for only a few in the European MCMDM-1VWD study. Additional expression studies of mutant VWF will help to predict normal or abnormal banding of mutant VWF multimers as the cause of a normal or smeary pattern in heterozygous cases [31,38,39,40,41].…”