Standardization of Light Transmission Aggregometry for Diagnosis of Platelet Disorders: An Inter-Laboratory External Quality Assessment.

AbstractSeveral in vitro platelet function tests are available for the diagnosis of inherited platelet function disorders. Currently, the light transmission aggregometry (LTA) is recommended as one of the first-step tests. LTA is available in most specialized hemostasis laboratories. Although the LTA is accepted as a ‘gold standard’ assay for the evaluation of platelet function, its standardization in the clinical practice is still challenging. The GTH-based THROMKID-Plus Study Group has performed an inter-laboratory trial in Germany and Austria. Five different agonists were selected according to the Scientific and Standardization Committee/International Society on Thrombosis and Haemostasi…

Age-dependent control of collagen-dependent platelet responses by thrombospondin-1 : Comparative analysis of platelets from neonates, children, adolescents, and adults

Platelet function is developmentally regulated. Healthy neonates do not spontaneously bleed, but their platelets are hypo-reactive to several agonists. The mechanisms underlying immature platelet function in neonates are incompletely understood. This critical issue remains challenging for the establishment of age-specific reference ranges. In this study, we evaluated platelet reactivity of five pediatric age categories, ranging from healthy full-term neonates up to adolescents (11–18 years) in comparison to healthy adults (&gt

Severe plasma prekallikrein deficiency : clinical characteristics, novel KLKB1 mutations, and estimated prevalence

BACKGROUND Severe plasma prekallikrein (PK) deficiency is an autosomal-recessive defect characterized by isolated activated partial thromboplastin time prolongation. To date, no comprehensive methodologically firm analysis has investigated the diagnostic, clinical, and genetic characteristics of PK deficiency, and its prevalence remains unknown. PATIENTS/METHODS We described new families with PK deficiency, retrieved clinical and laboratory information of cases systematically searched in the (gray) literature, and collected blood of these cases for complementary analyses. The Genome Aggregation Database (gnomAD) and the population-based Gutenberg Health Study served to study the prevalence …

The First THROMKID-Plus Inter-laboratory Survey - Standardization and Quality Management of Platelet Light Transmission Aggregometry for the Diagnosis of Inherited Platelet Function Disorders in German-speaking Countries

Detection and Differential Diagnosis of Prekallikrein Deficiency: Genetic Study of New Families and Systematic Review of the Literature

Abstract Introduction. Prekallikrein (PK) and high-molecular-weight kininogen (HK) deficiencies are ultra-rare, autosomal-recessive defects of the contact system caused by biallelic mutations in the KLKB1 and KNG1 genes, respectively. Since affected subjects do not manifest a bleeding phenotype, a correct diagnosis is essential to prevent the administration of prohemostatic agents or plasma and to avoid delay of surgery. We describe a new case of PK deficiency identified at UMC Mainz. In addition, we performed a systematic review of the literature in order to i) collect blood material for genetic studies of reported PK deficient cases lacking this information, and ii) perform a comprehensiv…

Validation of the ISTH/SSC bleeding assessment tool for inherited platelet disorders: A communication from the Platelet Physiology SSC

Background: Careful assessment of bleeding history is the first step in the evaluation of patients with mild/moderate bleeding disorders, and the use of a bleeding assessment tool (BAT) is strongly encouraged. Although a few studies have assessed the utility of the ISTH-BAT in patients with inherited platelet function disorders (IPFD) none of them was sufficiently large to draw conclusions and/or included appropriate control groups. Objectives: The aim of the present study was to test the utility of the ISTH-BAT in a large cohort of patients with a well-defined diagnosis of inherited platelets disorder in comparison with two parallel cohorts, one of patients with type-1 von Willebrand disea…

Impaired Platelet Function in Sept8-Deficient Mice In Vitro.

AbstractSeptins (Septs) are a widely expressed protein family of 13 mammalian members, recognized as a unique component of the cytoskeleton. In human platelets, we previously described that SEPT4 and SEPT8 are localized surrounding α-granules and move to the platelet surface after activation, indicating a possible role in platelet physiology. In this study, we investigated the impact of Sept8 on platelet function in vitro using Sept8-deficient mouse platelets. Deletion of Sept8 in mouse platelets caused a pronounced defect in activation of the fibrinogen receptor integrin αIIbβ3, α-granule exocytosis, and aggregation, especially in response to the glycoprotein VI agonist convulxin. In contr…