Thromb Haemost 2013; 109(04): 652-660
DOI: 10.1160/TH12-10-0737
Blood Coagulation, Fibrinolysis and Cellular Haemostasis
Schattauer GmbH

Phenotypic and molecular characterisation of type 3 von Willebrand disease in a cohort of Indian patients

Firdos Ahmad
1   Department of Haematology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
2   Center for Translational Medicine, School of Medicine Temple University, Philadelphia, Pennsylvania, USA
,
Ulrich Budde
3   Medilys Laboratory, Coagulation, Asklepios Hospital Altona, Hamburg, Germany
,
Rifat Jan
1   Department of Haematology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
,
Florian Oyen
4   Department of Pediatric Haematology Oncology, University Medical Centre Hamburg Eppendorf, Hamburg, Germany
,
Meganathan Kannan
1   Department of Haematology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
,
Renu Saxena
1   Department of Haematology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
,
Reinhard Schneppenheim
4   Department of Pediatric Haematology Oncology, University Medical Centre Hamburg Eppendorf, Hamburg, Germany
› Author Affiliations

Financial support: This work was supported by grants from Prof. Gunther Landbeck Stipendium (University Medical Center Hamburg, Germany) and Senior Research Fellowship (Indian Council of Medical Research, New Delhi) to Firdos Ahmad.
Further Information

Publication History

Received: 09 October 2012

Accepted after major revision: 17 January 2013

Publication Date:
22 November 2017 (online)

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Summary

Severe type 3 VWD (VWD3) is characterised by complete absence or presence of trace amounts of non-functional von Willebrand factor (VWF). The study was designed to evaluate the VWF mutations in VWD3 patients and characterise the breakpoints of two identified homozygous novel large deletions. Patients were diagnosed by conventional tests and VWF multimer analysis. Mutation screening was performed in 19 VWD3 patients by direct sequencing of VWF including flanking intronic sequence and multiplex ligation-dependent probe amplification (MLPA) analysis. Breakpoint characterisation of two identified novel large deletions was done using walking primers and long spanning PCR. A total of 21 different mutations including 15 (71.4%) novel ones were identified in 17 (89.5%) patients. Of these mutations, five (23.8%) were nonsense (p.R1659*, p.R1779*, p.R1853*, p.Q2470*, p.Q2520*), one was a putative splice site (p.M814I) and seven (33.3%) were deletions (p.L254fs*48, p.C849fs*60, p.L1871fs*6, p.E2720fs*24) including three novel large deletions of exon 14–15, 80,830bp (−41510_657+7928A*del) and 2,231bp [1534–2072T_c.1692G*del(p.512fs*terminus)] respectively. A patient carried gene conversion comprising of pseudogene harbouring mutations. The missense mutations (p.G19R, p.K355R, p.D437Y, p.C633R, p.M771V, p.G2044D, p.C2491R) appear to play a major role and were identified in seven (36.8%) patients. In conclusion, a high frequency of novel mutations suggests the high propensity of VWF for new mutations. Missense and deletion mutations found to be a common cause of VWD3 in cohort of Indian VWD3 patients. Breakpoints characterisation of two large deletions reveals the double strand break and non-homologous recombination as deletions mechanism.