Thromb Haemost 2016; 115(01): 51-62
DOI: 10.1160/TH15-02-0119
Coagulation and Fibrinolysis
Schattauer GmbH Schattauer

The D173G mutation in ADAMTS-13 causes a severe form of congenital thrombotic thrombocytopenic purpura

A clinical, biochemical and in silico study
Stefano Lancellotti#
1   Center for Haemorrhagic and Thrombotic Diseases, Department of Medical Sciences, Catholic University School of Medicine, Rome, Italy
,
Flora Peyvandi#
2   Angelo Bianchi Bonomi Hemophilia and Thrombosis Center and Fondazione Luigi Villa, IRCCS Maggiore Hospital, Mangiagalli, Regina Elena Foundation and University of Milan, Milan, Italy
,
Maria Teresa Pagliari
2   Angelo Bianchi Bonomi Hemophilia and Thrombosis Center and Fondazione Luigi Villa, IRCCS Maggiore Hospital, Mangiagalli, Regina Elena Foundation and University of Milan, Milan, Italy
,
Andrea Cairo
2   Angelo Bianchi Bonomi Hemophilia and Thrombosis Center and Fondazione Luigi Villa, IRCCS Maggiore Hospital, Mangiagalli, Regina Elena Foundation and University of Milan, Milan, Italy
,
Safwat Abdel-Azeim
3   Kaust Catalysis Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
,
Edrisse Chermak
3   Kaust Catalysis Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
,
Ilaria Lazzareschi
4   Institute of Pediatrics, Catholic University School of Medicine, Rome, Italy
,
Stefano Mastrangelo
4   Institute of Pediatrics, Catholic University School of Medicine, Rome, Italy
,
Luigi Cavallo
3   Kaust Catalysis Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
,
Romina Oliva§
5   Department of Sciences and Technologies, University “Parthenope” of Naples, Naples, Italy
,
Raimondo De Cristofaro
1   Center for Haemorrhagic and Thrombotic Diseases, Department of Medical Sciences, Catholic University School of Medicine, Rome, Italy
› Author Affiliations

Financial support: This work has been in part supported by the Catholic University School of Medicine to RDC grant “Linea D1” 2012/2013” and grant “Linea D1” 2013–2014. The study was supported by the Italo Monzino Foundation (FP).
Further Information

Publication History

Received: 09 February 2015

Accepted after major revision: 28 June 2015

Publication Date:
22 November 2017 (online)

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Summary

Congenital thrombotic thrombocytopenic purpura (TTP) is a rare form of thrombotic microangiopathy, inherited with autosomal recessive mode as a dysfunction or severe deficiency of ADAMTS-13 (A Disinte-grin And Metalloprotease with ThromboSpondin 1 repeats Nr. 13), caused by mutations in the ADAMTS-13 gene. About 100 mutations of the ADAMTS-13 gene were identified so far, although only a few char-acterised by in vitro expression studies. A new Asp to Gly homozygous mutation at position 173 of ADAMTS-13 sequence was identified in a family of Romanian origin, with some members affected by clinical signs of TTP. In two male sons, this mutation caused a severe (< 3 %) deficiency of ADAMTS-13 activity and antigen level, associated with periodic thrombocytopenia, haemolytic anaemia and mild mental confusion. Both parents, who are cousins, showed the same mutation in heterozygous form. Expression studies of the mutant ADAMTS-13, performed in HEK293 cells, showed a severe decrease of the enzyme’s activity and secretion, although the protease was detected inside the cells. Molecular dynamics found that in the D173G mutant the interface area between the metalloprotease domain and the disintegrin-like domain significantly decreases during the simulations, while the proline-rich 20 residues linker region (LR, 285–304) between them undergoes extensive conformational changes. Inter-domain contacts are also significantly less conserved in the mutant compared to the wild-type. Both a decrease of the inter-domain contacts along with a substantial conformational rearrangement of LR interfere with the proper maturation and folding of the mutant ADAMTS-13, thus impairing its secretion.

Supplementary Material to this article is available online at www.thrombosis-online.com.

# Equal contribution.


§ Senior coauthor.