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Genotyping and platelet phenotyping (GAPP)

Mild bleeding disorders caused by platelet defects

Haematology (co-adopted by Children, PrimaryCare)
Portfolio Eligibility
Automatically eligible
ISRCTN 77951167
MREC N° 06/MRE07/36
Research Summary
Summary It is becoming increasingly recognised that platelet function disorders are heavily under diagnosed and therefore under researched. Several factors have contributed to this including: • The absence of a ‘gold standard’ point-of-care assay of platelet function • The generally asymptomatic presentation of patients with mild defects in platelet function who only exhibit symptoms of excessive bleeding when subject to an appropriate challenge such as surgery or severe injury • The considerable redundancy in the pathways underlying platelet activation such that a single gene defect may not be sufficient to give rise to excessive bleeding (but may become clinically important under challenging conditions); • The limited amount of mRNA that can be recovered from the anucleate platelet which severely hampers many standard approaches in molecular biology including use of microarrays. The Birmingham Platelet Group has an approach to gene mapping of platelet disorders based on initial evaluation of clinical and laboratory phenotypes of patients with clinically diagnosed bleeding disorders and subsequent targeted gene sequencing. In this project, we intend to investigate populations of patients enriched for bleeding to test the hypothesis that a proportion of patients who present with excessive bleeding have a previously unrecognised impairment in platelet function which may explain their propensity to bleed in conditions which would not normally be associated with severe bleeding. The proposed research will use a combination of platelet phenotyping and targeted gene sequencing approach to identify candidate mutations underlying platelet dysfunction. The effect of a small number of missense mutations on protein function will be investigated through expression studies in immortalised cell lines. Identification of novel gene defects would provide information on genes and proteins involved in normal platelet physiology and would
Study Type Observational
Design Type Not specified
Disease(s) Non-malignant haematology
All Diseases
All Diseases
Phase N/A
Current Status Open
Closure Date 12/31/2016
Global Sample Size 800
Global Recruitment to Date
Geographical Scope UK Multi-Centre
Lead Country England (also active in Scotland and Wales)
Open to new sites Yes, within lead country only
Main Inclusion Criteria
 Patients, aged 0 – 85 years
 Diagnosed with a platelet disorder of unknown cause
 Willing to participate and able to provide informed consent
Main Exclusion Criteria
 Patients taking drugs that are known to influence platelet function, including nonsteroidal anti-inflammatory drugs (NSAIDs, including COX-2 selective anti-inflammatory drugs), aspirin, clopidogrel, dipyridamole, warfarin or acenocoumarol within 7 days of enrolment
 Patients having undergone a major surgical procedure within 1 month of enrolment
 Patients with chronic renal failure requiring dialysis
 Patients with a platelet count outside the 100 000 to 450 000/μL range
 Patients with severe anaemia (Haemoglobin < 8g/dl)
Chief Investigator(s)
Prof Stephen Watson
Further details, please contact
Prof Stephen Watson

University of Birmingham
Department of Cardiovascular Medicine
Medical School

West Midlands
B15 2TT

Tel: 0121 415 6514
Funder(s) Wellcome Trust
British Heart Foundation (BHF)
Sponsor(s) University of Birmingham
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