Assays measuring platelet aggregation (thrombus formation) at arterial shear rate mostly use collagen as only platelet-adhesive surface. Here we report a multi-surface and multi-parameter flow assay to characterize thrombus formation in whole blood from healthy subjects and patients with platelet function deficiencies. A systematic comparison is made of 52 adhesive surfaces with components activating the main platelet-adhesive receptors, and of eight output parameters reflecting distinct stages of thrombus formation. Three types of thrombus formation can be identified with a predicted hierarchy of the following receptors: glycoprotein (GP)VI, C-type lectin-like receptor-2 (CLEC-2)>GPIb>α6β1, αIIbβ3>α2β1>CD36, α5β1, αvβ3. Application with patient blood reveals distinct abnormalities in thrombus formation in patients with severe combined immune deficiency, Glanzmann’s thrombasthenia, Hermansky–Pudlak syndrome, May–Hegglin anomaly or grey platelet syndrome. We suggest this test may be useful for the diagnosis of patients with suspected bleeding disorders or a pro-thrombotic tendency.

Non-surgical postoperative bleeding after VAD implantation could be explained by an AVWD. Several pharmacologic treatment options (tranexamic acid, desmopressin, VWF-factor VIII concentrate, recombinant factor VIIa) may arise from our data. Improved VAD design could prevent this problem in the future.

MYH9-related disease (MYH9-RD) is a rare autosomal-dominant disorder caused by mutations in the gene for nonmuscle myosin heavy chain IIA (NMMHC-IIA). MYH9-RD is characterized by a considerable variability in clinical evolution: patients present at birth with only thrombocytopenia, but some of them subsequently develop sensorineural deafness, cataract, and/or nephropathy often leading to end-stage renal disease (ESRD). We searched for genotype-phenotype correlations in the largest series of consecutive MYH9-RD patients collected so far (255 cases from 121 families). Association of genotypes with noncongenital features was assessed by a generalized linear regression model. The analysis defined disease evolution associated to seven different MYH9 genotypes that are responsible for 85% of MYH9-RD cases. Mutations hitting residue R702 demonstrated a complete penetrance for early-onset ESRD and deafness. The p.D1424H substitution associated with high risk of developing all the noncongenital manifestations of disease. Mutations hitting a distinct hydrophobic seam in the NMMHC-IIA head domain or substitutions at R1165 associated with high risk of deafness but low risk of nephropathy or cataract. Patients with p.E1841K, p.D1424N, and C-terminal deletions had low risk of noncongenital defects. These findings are essential to patients' clinical management and genetic counseling and are discussed in view of molecular pathogenesis of MYH9-RD.

the Childhood Stroke Study GroupBackground-The present study was performed to assess the association of prothrombotic risk factors and underlying conditions (infections, vascular trauma, immobilization, malignancies, autoimmune diseases, renal diseases, metabolic disorders, obesity, birth asphyxia, cardiac malformations, and use of prothrombotic drugs) with cerebral venous thrombosis (CVT) in children. Methods and Results-From 1995 to 2002, 149 pediatric patients aged newborn to Ͻ18 years (median 6 years) with CVT were consecutively enrolled. In patients and in 149 age-and gender-matched children with similar underlying clinical conditions but without CVT, the factor V G1691A mutation, the factor II G20210A variant, lipoprotein(a) [Lp(a)], protein C, protein S, antithrombin, and antiphospholipid antibodies, as well as associated clinical conditions, were investigated. Eighty-four (56.4%) of the patients had at least 1 prothrombotic risk factor compared with 31 control children (20.8%; PϽ0.0001). In addition, 105 (70.5%) of 149 patients with CVT presented with an underlying predisposing condition. On univariate analysis, factor V, protein C, protein S, and elevated Lp(a) were found to be significantly associated with CVT. However, in multivariate analysis, only the combination of a prothrombotic risk factor with an underlying condition (OR 3.9, 95% CI 1.8 to 8.6), increased Lp(a) (OR 4.1, 95% CI 2.0 to 8.7), and protein C deficiency (OR 11.1, 95% CI 1.2 to 104.4) had independent associations with CVT in the children investigated. Conclusions-CVT in children is

Griscelli syndrome (GS) was diagnosed in a 2-year-old patient with oculocutaneous albinism and immunodeficiency, but sequencing of RAB27a revealed only a heterozygous mutation. Due to impaired natural killer (NK) and T-cell cytotoxicity implying a high risk of developing hemophagocytic lymphohistiocytosis (HLH), he was prepared for hematopoietic stem cell transplantation (HSCT). Unexpectedly, a severe bleeding episode occurred that led to the demonstration of disturbed platelet aggregation, reduced plateletdense granules, and impaired platelet degranulation. In combination with neutropenia, this suggested the diagnosis of Hermansky-Pudlak syndrome type II (HPSII) and a novel homozygous mutation in AP3B1 was detected. None of the 3 reported HPSII patients had developed HLH, and our patient seroconverted to Epstein-Barr virus (EBV) without clinical symptoms. HSCT was therefore withheld, and granulocyte-colony-stimulating factor (G-CSF) therapy was initiated and prevented further bacterial infections. At 3 years of age, however, the patient developed, without an obvious trigger, fulminant HLH that was resistant to therapy. This patient shows that careful clinical and molecular diagnosis is essential to differentiate the complex disorders of ly- IntroductionSecretory lysosomes are cellular organelles involved in trafficking and exocytosis of intracellular proteins. 1 They have important functions in several cell types including melanocytes, neuronal cells, platelets, granulocytes, mast cells, natural killer (NK) cells, and T cells. 2 The protein machinery required for adequate biogenesis, transport, and delivery of secretory lysosomes has a variable composition in each cell type. Therefore, the clinical phenotype of diseases due to genetic defects in proteins involved in lysosomal trafficking varies widely despite the similar cell-biologic basis. This has led to their classification as predominantly dermatologic, hematologic, hemostaseologic, or immunologic disorders. While the 7 genetically defined Hermansky-Pudlak syndromes (HPSs) predominantly present as bleeding disorders, 3 the most important clinical problem of patients with Chédiak-Higashi syndrome (CHS) and Griscelli syndrome type II (GSII) is immunodeficiency. 4 Neurologic defects characterize GSI and CHS, 5 while patients with GSIII show only oculocutaneous albinism. 6 This latter feature links all of these syndromes. However, studies showing that also some forms of familial hemophagocytic lymphohistiocytosis (FHL) represent lysosomal trafficking disorders 7,8 revealed that albinism is not a constant feature in this heterogenous family of diseases.Lysosomal trafficking disorders associated with immunodeficiency are life-threatening conditions due to the high risk of developing hemophagocytic lymphohistiocytosis (HLH). 4 HLH is a systemic inflammatory disorder characterized by uncontrolled CD8 ϩ T-cell and macrophage activation with infiltration of multiple tissues. 9 The common defect in most genetic diseases predisposing to HLH is disturbed secretion of ...

SummaryBackgroundThe relative importance of previous diagnosis and hereditary prothrombotic risk factors for cerebral venous thrombosis (CVT) in children in determining risk of a second cerebral or systemic venous thrombosis (VT), compared with other clinical, neuroimaging, and treatment variables, is unknown.MethodsWe followed up the survivors of 396 consecutively enrolled patients with CVT, aged newborn to 18 years (median 5·2 years) for a median of 36 months (maximum 85 months). In accordance with international treatment guidelines, 250 children (65%) received acute anticoagulation with unfractionated heparin or low-molecular weight heparin, followed by secondary anticoagulation prophylaxis with low-molecular weight heparin or warfarin in 165 (43%).ResultsOf 396 children enrolled, 12 died immediately and 22 (6%) had recurrent VT (13 cerebral; 3%) at a median of 6 months (range 0·1–85). Repeat venous imaging was available in 266 children. Recurrent VT only occurred in children whose first CVT was diagnosed after age 2 years; the underlying medical condition had no effect. In Cox regression analyses, non-administration of anticoagulant before relapse (hazard ratio [HR] 11·2 95% CI 3·4–37·0; p<0·0001), persistent occlusion on repeat venous imaging (4·1, 1·1–14·8; p=0·032), and heterozygosity for the G20210A mutation in factor II (4·3, 1·1–16·2; p=0·034) were independently associated with recurrent VT. Among patients who had recurrent VT, 70% (15) occurred within the 6 months after onset.ConclusionAge at CVT onset, non-administration of anticoagulation, persistent venous occlusion, and presence of G20210A mutation in factor II predict recurrent VT in children. Secondary prophylactic anticoagulation should be given on a patient-to-patient basis in children with newly identified CVT and at high risk of recurrent VT. Factors that affect recanalisation need further research.

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Our data indicate that AVWS is a typical disorder in patients with ECLS. We hypothesize that AVWS could contribute to aggravation of bleeding tendencies in ECLS patients.