Rare Variants in the ADAMTS13 Von Willebrand Factor–Binding Domain Contribute to Pediatric Stroke

Abstract

Background-Recently, we reported a gene network of ADAMTS (A Disintegrin-like and Metalloprotease with Thrombospondin motifs) genes as central component of the genetic risk contributing to pediatric stroke. ADAMTS13 is a prime example for such a key component as it cleaves von Willebrand factor multimers, reduces platelet adhesion and aggregation, and downregulates thrombus formation and inflammation. Methods and Results-We characterized the genetic architecture of ADAMTS13 through targeted next-generation sequencing of 48 affected children and their unaffected siblings and identified in total 241 variants (single nucleotide polymorphisms or insertions/deletions) in the ADAMTS13 gene. From these, based on significance in the sibship disequilibrium test (P<0.05) or protein-altering properties, we selected 21 common variants covering the complete ADAMTS13 gene for genotyping in 270 trios and subsequent association analyses. Transmission disequilibrium testing was performed for affection status and ADAMTS13 activity levels using PLINK and FBAT, respectively. Ten single nucleotide polymorphisms were significantly associated with pediatric stroke (P<0.05 to P<0.001), 2 of which (rs2285489 and rs28793911) were also significantly associated with ADAMTS13 levels (P=0. 0004 and P=0.0092 In 2012, we reported a genome-wide association study in 270 affected offspring trios, which demonstrates the association of several members of the ADAMTS gene family with pediatric stroke 11 including a moderate association of single nucleotide polymorphisms (SNPs) in the vicinity of ADAMTS13. In parallel, we extended our studies to include the association of ADAMTS13 plasma levels as an intermediate phenotype and the risk for pediatric stroke 2 and demonstrated that decreased ADAMTS13 activity is a risk factor (odds ratio, 6.70; 95% confidence interval, 2.58-17.38) for incident ischemic stroke in children without underlying disease.In the present study, we characterized the genomic architecture underlying ADAMTS13 through a targeted nextgeneration sequencing approach in 48 pairs of patients with pediatric stroke and their unaffected siblings. Twenty-one ADAMTS13 variants identified in this discovery stage were subsequently genotyped in the above-mentioned cohort of 270 affected offspring trios and analyzed by transmission disequilibrium testing for association with stroke affection status and ADAMTS13 serum levels. By this, we establish a causal relationship between ADAMTS13 single nucleotide variants, ADAMTS13 levels, and pediatric stroke susceptibility. Methods Subjects EthicsThe present study was performed in accordance with the ethical standards laid down in the updated version of the 1964 Declaration of Helsinki and was approved by the medical ethics committee of the University of Münster, Germany. Written informed consent was obtained from all participants or their parent(s). PatientsEnrollment and characterization of affected family trios have been described in detail in our initial genome-wide association study publication.11 In ...

Reduced ADAMTS13 levels in patients with acute and chronic cerebrovascular disease

“…[16] Likewise, a link was recently identified between the genetic architecture of ADAMTS13, ADAMTS13 levels and stroke susceptibility. [17] These results all point towards a possible causative role for ADAMTS13 in the development of acute ischemic stroke in patients. Reduced levels of ADAMTS13 indeed could lead to a prothrombotic state allowing local accumulation of ultra large VWF at sites of vascular damage, promoting the formation of (VWF-rich) thrombo-embolic occlusions.…”

ADAMTS12, a new candidate gene for pediatric stroke

“…Written confirmed consent was obtained from all participants or their parents. Enrollment and genotyping of affected pediatric stroke family trios, probands selection and characteristics of 48 independent pediatric probands and 48 unaffected siblings has been described by Arning et al and Stoll et al [ 1 , 3 ]. From the same catchment area, 189 offspring trios for pediatric venous thromboembolism (VTE) enrolled from neonates and children with confirmed diagnosis of VTE not older than 18 years at onset and having available nonaffected biological brothers, sisters and parents were utilized for the pseudo-replication study and are described in detail by Rühle et al [ 8 ].…”

“…Pediatric stroke happens with an incidence of 2.6–6.4 per 100 000 children per year and is still one of the top 10 causes of death in children [ 1 , 2 ]. Extracellular matrix components like members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) gene family, primarily ADAMTS13 , in combination with misbalanced coagulation signals appear to play an important role in pediatric stroke etiology after postnatal vascular injuries [ 3 , 4 ].…”

Genetic variants in ADAMTS13 as well as smoking are major determinants of plasma ADAMTS13 levels

“…3 Previous studies have reported loss of higher-molecular-weight multimers in the bleeding disorder von Willebrand disease type 2A, and conversely, an accumulation of ultralarge VWF monomers 4 in thrombotic thrombocytopenic purpura, 5 demonstrating the importance of the regulation of VWF activity by ADAMTS13. Recent reports have also linked lower ADAMTS13 plasma concentrations with an increased risk of ischemic stroke, 6,7 coronary artery disease, and all-cause mortality. 8,9 Unlike many proteases, ADAMTS13 is secreted in an active form and, to date, no specific inhibitor of ADAMTS13 has been identified.…”