title: Impaired platelet function in a patient with P2Y12 deficiency caused by a mutation in the translation initiation codon.
abstract: In this study, we have identified a patient (OSP-1) with a congenital P2Y12 deficiency showing a mild bleeding tendency from her childhood and examined the role of P2Y12 in platelet function. At low concentrations of agonists OSP-1 platelets showed an impaired aggregation to several kinds of stimuli, whereas at high concentrations they showed a specifically impaired platelet aggregation to adenosine diphosphate (ADP). ADP normally induced platelet shape change and failed to inhibit PGE1-stimulated cAMP accumulation in OSP-1 platelets. Molecular genetic analysis revealed that OSP-1 was a homozygous for a mutation in the translation initiation codon (ATG to AGG) in the P2Y12 gene. Heterologous cell expression of wild-type or mutant P2Y12 confirmed that the mutation was responsible for the deficiency in P2Y12. OSP-1 platelets showed a markedly impaired platelet spreading onto immobilized fibrinogen. Real-time observations of thrombogenesis under a high shear rate (2000 s(-1)) revealed that thrombi over collagen were small and loosely packed and most of the aggregates were unable to resist against high shear stress in OSP-1. Our data suggest that secretion of endogenous ADP and subsequent P2Y12-mediated signaling are critical for platelet aggregation, platelet spreading, and as a consequence, for stabilization of thrombus.
authors.affiliation: Department of Hematology and Oncology, Graduate School of Medicine C9, Osaka University, Osaka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Shiraga
authors.forename: S
authors.initials: S
authors.lastname: Miyata
authors.forename: H
authors.initials: H
authors.lastname: Kato
authors.forename: H
authors.initials: H
authors.lastname: Kashiwagi
authors.forename: S
authors.initials: S
authors.lastname: Honda
authors.forename: Y
authors.initials: Y
authors.lastname: Kurata
authors.forename: Y
authors.initials: Y
authors.lastname: Tomiyama
authors.forename: Y
authors.initials: Y
authors.lastname: Kanakura
mesh_terms: D000368:Aged; D001791:Blood Platelet Disorders / Q000235:genetics*; D001792:Blood Platelets / Q000473:pathology*; D002460:Cell Line; D048430:Cell Shape / Q000235:genetics; D018387:Codon, Initiator / Q000235:genetics*; D000242:Cyclic AMP / Q000032:analysis; D004252:DNA Mutational Analysis; D005260:Female; D006720:Homozygote; D006801:Humans; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics; D010974:Platelet Aggregation / Q000235:genetics; D017354:Point Mutation; D018048:Receptors, Purinergic P2 / Q000172:deficiency* / Q000235:genetics; D058925:Receptors, Purinergic P2Y12; D013927:Thrombosis / Q000235:genetics; D014162:Transfection
chemical_list: D018387:Codon, Initiator; D008565:Membrane Proteins; C548576:P2RY12 protein, human; D018048:Receptors, Purinergic P2; D058925:Receptors, Purinergic P2Y12; D000242:Cyclic AMP