Submitted November 20, 2008
Accepted February 6, 2009
Identification and characterisation of a novel P2Y12 variant in a patient diagnosed with type 1 von Willebrand disease in the European MCMDM-1VWD study
Martina E. Daly*, Ban B. Dawood, William A. Lester, Ian R. Peake, Francesco Rodeghiero, Anne C. Goodeve, Michael Makris, Jonathan T. Wilde, Andrew D. Mumford, Stephen P. Watson, and Stuart J. Mundell
Academic Unit of Haematology, School of Medicine and Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
Centre for Cardiovascular Sciences, University of Birmingham, Birmingham, United Kingdom
West Midlands Adult Haemophilia Centre, University Hospital Birmingham NHS Trust, Birmingham, United Kingdom
Hematology Department, San Bortolo Hospital, Vicenza, Italy
Bristol Heart Institute, University of Bristol, Bristol Royal Infirmary, Bristol, United Kingdom
Department of Pharmacology, University of Bristol, Bristol, United Kingdom
* Corresponding author; email: m.daly{at}sheffield.ac.uk.
We investigated whether defects in the P2Y12 ADP receptor gene (P2RY12) contribute to the bleeding tendency in 92 index cases enrolled in the European MCMDM-1VWD study. A heterozygous mutation, predicting a lysine to glutamate (K174E) substitution in P2Y12, was identified in one case with mild type 1 VWD and a VWF defect. Platelets from the index case and relatives carrying the K174E defect changed shape in response to ADP, but showed reduced and reversible aggregation in response to 10 µM ADP, unlike the maximal, sustained aggregation observed in controls. The reduced response was associated with an approximate 50% reduction in binding of [3H]2MeS-ADP to P2Y12 whereas binding to the P2Y1 receptor was normal. A haemagglutinin-tagged K174E P2Y12 variant showed surface expression in CHO cells, markedly reduced binding to [3H]2MeS-ADP and minimal ADP-mediated inhibition of forskolin-induced adenylyl cyclase activity. Our results provide further evidence for locus heterogeneity in type 1 VWD.
