scholarly journals Characterization of Two Cases of Congenital Thrombotic Thrombocytopenic Purpura (TTP)

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 5005-5005
Author(s):  
Xia Bai ◽  
JIan Su ◽  
Lijuan Cao ◽  
Changgeng Ruan
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Binding Assay ◽  
Conflicts Of Interest ◽  
Hek293 Cells ◽  
Novel Mutations ◽  
Thrombocytopenic Purpura ◽  
Congenital Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Introduction: Congenital thrombotic thrombocytopenic purpura (TTP) is characterized by disseminated thrombus due to the mutations of ADAMTS13, which cleaves its substrate von Willebrand factor(VWF) in shear-induced unfolding condition. Most of the congenital TTP we found is woman with pregnancy. Here, we characterize two children suspected with congenital TTP. Methods:ADAMTS13 activities were analyzed by residual collagen binding assay (R-CBA) plus FRET-VWF substrate. And the inhibitors of ADAMTS13 were analyzed by 9:1 mixture of patient and pooled normal plasma followed by R-CBA. The secretion of recombinant ADAMTS13 mutants was studied. Results: Two children, one aged four months and the other aged three years old, were diagnosed with congenital TTP because their ADAMTS13 activities were less than 5% (both FRET-VWF and R-CBA), and there are short of ADAMTS13 inhibitors. The following mutations were found: Q1385P, Y177C, C522R. In addition to the previously reported mutation of Y177C, the two novel mutations (Q1385P and C522R) failed to secrete from the HEK293 cells. Conclusion: Two children with congenital TTP were determined thanks to screening of ADAMTS13 activity and its corresponding inhibitor assays, and it seems that congenital TTP could occur in different ages although most of congenital TTP we found were women with pregnancy. Disclosures No relevant conflicts of interest to declare.

Three Novel ADAMTS-13 Gene Mutations in Thrombotic Thrombocytopenic Purpura (TTP).

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3965-3965
Author(s):  
Nam Keun Kim ◽  
Moon Ju Jang ◽  
Sun Kim ◽  
Sun Ju Lee ◽  
Hye Won Park ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Thrombus Formation ◽  
Gene Mutations ◽  
Missense Mutations ◽  
Thrombocytopenic Purpura ◽  
Congenital Thrombotic Thrombocytopenic Purpura ◽  
Platelet Thrombus ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Splicing Site

Abstract ADAMTS-13 is an enzyme which cleave von Willebrand factor (VWF) to prevent excessive platelet thrombus formation. Mutation of ADAMTS-13 is associated with congenital thrombotic thrombocytopenic purpura (TTP). In this study, we report three novel missense mutations of ADAMTS-13 gene in TTP families. Genetic analysis of ADAMTS-13 gene was performed in 6 TTP families. Three novel ADAMTS-13 gene mutations (2708C>T [S903L], 3650T>C [I1217T] and 3941C>T [S1314L]) detected in 3 families. They were all found with heterozygous genotype in exon 21, 26 and 28, respectively. The 3650T>C mutation was found at exon 26 in the patient and his mother. A heterozygous guanine to adenine substitution was found at 5′ splicing site of intron 3(IVS+ 1) in the patient, his brother and his father. The plasma ADAMTS-13 activities of the patient, father, mother, and brother were less than 3%, 56%, 55% and 62% respectively. ADAMTS-13 inhibitors were not detected in all family members. 3941C>T was found at exon 28 in the patient and her father. The plasma ADAMTS-13 activities of the patient, father, and mother were 96%, 83%, and 83% respectively.

Congenital thrombotic thrombocytopenic purpura in association with a mutation in the second CUB domain of ADAMTS13

Blood ◽  
2004 ◽  
Vol 103 (2) ◽  
pp. 627-629 ◽  
Author(s):  
John E. Pimanda ◽  
Akiko Maekawa ◽  
Troels Wind ◽  
Julian Paxton ◽  
Colin N. Chesterman ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Proteinase Activity ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Thrombocytopenic Purpura ◽  
Severe Deficiency ◽  
Cub Domain ◽  
Congenital Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Severe deficiency of the von Willebrand Factor (VWF)–cleaving proteinase, ADAMTS13, is associated with the development of thrombotic thrombocytopenic purpura (TTP). Several mutations spread across the ADAMTS13 gene have been identified in association with a deficiency of VWF-cleaving proteinase activity in patients with congenital TTP. The spread of these dysfunctional mutations and the domain structure of ADAMTS13 are suggestive of a complex interaction between the enzyme and its substrate. We have studied a patient with congenital TTP who is a compound heterozygote for the Thr196Ile mutation in the metalloproteinase domain and a frameshift mutation (4143-4144insA) in the second CUB domain that results in loss of the last 49 amino acids of the protein. The VWF-cleaving proteinase activity of the truncated enzyme was comparable to that of the wild-type enzyme but its secretion from transfected COS-7 cells was about 14% of the wild type.

Gain-of-Function ADAMTS13 Variants Resistant to Anti-ADAMTS13 Autoantibody Inhibition: A Potential Novel Therapy for Acquired Autoimmune Thrombotic Thrombocytopenic Purpura

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1188-1188
Author(s):  
Cui Jian ◽  
Juan (Jenny) Xiao ◽  
Lingjie Gong ◽  
Christopher G. Skipwith ◽  
Sheng-Yu Jin ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Conflicts Of Interest ◽  
Specific Activity ◽  
Site Directed Mutagenesis ◽  
Binding Interaction ◽  
Novel Therapy ◽  
Thrombocytopenic Purpura ◽  
Von Willebrand ◽  
First Time ◽  
Willebrand Factor

Abstract Abstract 1188 Spacer domain of ADAMTS13 is essential for recognition and proteolytic cleavage of von Willebrand factor. It also contains major antigenic epitope targeted by anti-ADAMTS13 autoantibodies in patients with acquired (idiopathic) thrombotic thrombocytopenic purpura (TTP). Through site-directed mutagenesis and recombinant protein strategy, we identified two novel ADAMTS13 variants, which exhibited enhanced specific activity, but reduced inhibition by anti-ADAMTS13 autoantibodies. Among twenty-three ADAMTS13 variants tested, ADAMTS13-M4 (R660K/F592Y/R568K /Y661F) and ADAMTS13-M5 (R660K/F592Y/R568K /Y661F/Y665F) exhibited increased specific activity by 4∼5 fold and 12∼16 fold in cleavage of FRETS-VWF73 and plasma-derived multimeric VWF under denaturing conditions, respectively. Moreover, these two novel ADAMTS13 variants (i.e. M4 and M5) were resistant to inhibition by anti-ADAMTS13 IgG autoantibodies from 10 out of 12 acquired TTP patients tested. In contrast, proteolytic activity of wild-type ADAMTS13 and several other mutants (i.e. M1: R660K, M2: R660K/F592Y, and M3: R660K/F592Y/R568K) were significantly inhibited by same amount of anti-ADAMTS13 IgGs in all 12 patients' plasmas. The resistance to inhibition of these variants was the result of reduced binding interaction between the ADAMTS13 variants (M4 and M5) and the anti-ADAMTS13 IgGs. These findings demonstrate for the first time that an exosite modification in the spacer domain may be a viable strategy for identification of novel ADAMTS13 variants with more desirable enzymatic properties. The results provide a potential tool for treatment of acquired (autoimmune) TTP and perhaps other arterial thrombotic disorders. Disclosures: No relevant conflicts of interest to declare.

Identification of novel mutations in ADAMTS13 in an adult patient with congenital thrombotic thrombocytopenic purpura

Blood ◽  
2004 ◽  
Vol 104 (7) ◽  
pp. 2081-2083 ◽  
Author(s):  
Toshihiro Uchida ◽  
Hideo Wada ◽  
Minoru Mizutani ◽  
Miho Iwashita ◽  
Hiroaki Ishihara ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Type I ◽  
Adamts13 Activity ◽  
Novel Mutations ◽  
Thrombocytopenic Purpura ◽  
Japanese Male ◽  
Old Japanese ◽  
Congenital Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand

Abstract Congenital thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) is associated with an inherited von Willebrand factor-cleaving protease (ADAMTS13 [a disintegrin and metalloprotease with thrombospondin type I domains 13]) deficiency. In this study, we identified novel mutations in the ADAMTS13 gene in a patient with TTP. The patient was a 51-year-old Japanese male who exhibited TTP symptoms at frequent intervals. The ADAMTS13 activity during acute episodes was less than 3% that of normal. The enzyme activities of the patient's father and mother were both 46%, and both parents were asymptomatic. Genetic analysis revealed that the patient was a compound heterozygote for 2 mutations. One mutation was a missense mutation in the metalloprotease domain (A250V, exon 7), and the other was a guanine to adenine substitution at the 5′ end of intron 3 (intron 3 G→A). In vitro expression studies revealed that the A250V mutation markedly reduced ADAMTS13 activity and the intron 3 G→A mutation caused abnormal mRNA synthesis. (Blood. 2004;104: 2081-2083)

scholarly journals Mutation of the H-bond acceptor S119 in the ADAMTS13 metalloprotease domain reduces secretion and substrate turnover in a patient with congenital thrombotic thrombocytopenic purpura

Blood ◽  
2009 ◽  
Vol 114 (21) ◽  
pp. 4749-4752 ◽  
Author(s):  
Hendrik B. Feys ◽  
Inge Pareyn ◽  
Renee Vancraenenbroeck ◽  
Marc De Maeyer ◽  
Hans Deckmyn ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Michaelis Constant ◽  
Thrombocytopenic Purpura ◽  
Polar Interaction ◽  
Congenital Thrombotic Thrombocytopenic Purpura ◽  
Catalytic Rate ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Conserved Residue

Abstract Hereditary thrombotic thrombocytopenic purpura is caused by mutations in adisintegrin and metalloprotease with thrombospondin motifs (ADAMTS13) resulting in defective processing of von Willebrand factor (VWF) that causes intravascular platelet aggregation culminating in thrombocytopenia with shistocytic anemia. In this study the functional and structural role of a recently identified ADAMTS13 metalloprotease domain mutation S119F was investigated. Secretion from heterologous cells was hampered but not completely eliminated. Secreted S119F was active toward multimeric VWF and FRETS-VWF73 but with abnormal kinetics, having a significantly reduced overall catalytic rate (kcat; 0.88 ± 0.04 s−1 vs 2.78 ± 0.11 s−1) and slightly smaller Michaelis constant (KM; 1.4 ± 0.2μM vs 2.3 ± 0.3μM). A computational model of the metalloprotease domain demonstrates both steric and polar interaction effects caused by S119F. Interestingly, mutant S119A has properties similar to S119F (kcat = 0.82 ± 0.03 s−1 and KM = 1.1 ± 0.1μM), allowing to assign distorted kinetics to the loss of the H-bond with conserved residue W262. We conclude that the S119-W262 H-bond is crucial for maximal turnover.

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