Whole exome sequencing identifies genetic variants in inherited thrombocytopenia with secondary qualitative function defects

Inherited thrombocytopenias are a heterogeneous group of disorders characterised by abnormally low platelet counts which can be associated with abnormal bleeding. Next generation sequencing has previously been employed in these disorders for the confirmation of suspected genetic abnormalities, and more recently in the discovery of novel disease causing genes. However its full potential has not previously been utilised. Over the past 6 years we have sequenced the exomes from 55 patients, including 37 index cases and 18 additional family members, all of whom were recruited to the UK Genotyping and Phenotyping of Platelets study. All patients had inherited or sustained thrombocytopenia of unknown aetiology with platelet counts varying from 11-186x109 /L. Of the 51 patients phenotypically tested, 37 (73%), had an additional secondary qualitative platelet defect. Using whole exome sequencing analysis we have identified “pathogenic” or “likely pathogenic” variants in 46% (17/37) of our index patients with thrombocytopenia. In addition, we report variants of uncertain significance in 12 index cases which include novel candidate genetic variants in previously unreported genes in four index cases. These results demonstrate that whole exome sequencing is an efficient method for elucidating potential pathogenic genetic variants in inherited thrombocytopenia. Whole exome sequencing also has the added benefit of discovering potentially pathogenic genetic variants for further study in novel genes not previously implicated in inherited thrombocytopenia

Clinical practice: The bleeding child. Part II: Disorders of secondary hemostasis and fibrinolysis

Bleeding complications in children may be caused by disorders of secondary hemostasis or fibrinolysis. Characteristic features in medical history and physical examination, especially of hemophilia, are palpable deep hematomas, bleeding in joints and muscles, and recurrent bleedings. A detailed medical and family history combined with a thorough physical examination is essential to distinguish abnormal from normal bleeding and to decide whether it is necessary to perform diagnostic laboratory evaluation. Initial laboratory tests include prothrombin time and activated partial thromboplastin time. Knowledge of the classical coagulation cascade with its intrinsic, extrinsic, and common pathways, is useful to identify potential defects in the coagulation in order to decide which additional coagulation tests should be performed

Factor 11 single-nucleotide variants in women with heavy menstrual bleeding

In a previous study it was shown that lower factor XI (FXI) levels in women with heavy menstrual bleeding (HMB). Our aim was to determine the single-nucleotide variants (SNVs) in the F11 gene in women with HMB. In addition, an extensive literature search was performed to determine the clinical significance of each SNV. Patients referred for HMB (PBAC-score >100) were included. With direct sequencing analysis of all 15 exons and flanking introns of the F11 gene, 29 different non-structural SNVs were detected in 49 patients with HMB. Interestingly, most of these SNVs have previously been associated with venous thrombosis instead of bleeding. These findings have not helped to elucidate the molecular basis of HMB. They also question the specificity of previously reported F11 variations in patients with thrombosis. More studies are needed to explain the lower FXI levels seen in patients with HMB

High rates of unsuccessful transfer to adult care among young adults with juvenile idiopathic arthritis

<p>Abstract</p> <p>Background</p> <p>This study aimed to describe the proportion of patients with juvenile idiopathic arthritis (JIA) who had experienced an unsuccessful transfer from a pediatric rheumatology team to an adult rheumatologist and to compare the characteristics of those who achieved successful transfer to those who did not.</p> <p>Methods</p> <p>We conducted a systematic chart review of all patients with JIA who attended their final Montreal Children's Hospital JIA clinic appointment between 1992 and 2005. We tracked these patients for the two years after transfer to an adult rheumatologist. We then compared characteristics of patients with successful and unsuccessful transfers of care. Variables pertaining to disease characteristics, disease severity and psychosocial factors were examined. Univariate analyses were performed to determine if any single factor was associated with the outcome of unsuccessful transfer of care.</p> <p>Results</p> <p>52% of patients fulfilled our criteria for unsuccessful transfer. Of the variables tested, an active joint count (AJC) of zero at last visit was associated with the outcome of unsuccessful transfer (OR = 2.67 (CI 1.16-6.16; p = 0.0199)).</p> <p>Conclusions</p> <p>Despite the presence of a coordinated process of transfer from pediatric to adult health care for the majority of the patients in this study, there was a high rate of unsuccessful transfer and/or sustained follow up which is disheartening. We found that patients with less active disease at the time of transfer, as indicated by a lower AJC, were more likely to be lost to follow up. Recent literature suggests that even in the least severe categories of JIA, 50% of patients persist with active disease into adulthood. Thus educating all JIA patients about the possibility of disease flare in adulthood may improve their adherence to recommendations for sustained follow-up in the adult milieu. This may lead to improvement of longitudinal outcomes for all JIA patients.</p

Application of theory to enhance audit and feedback interventions to increase the uptake of evidence-based transfusion practice: an intervention development protocol

Background: Audits of blood transfusion demonstrate around 20% transfusions are outside national recommendations and guidelines. Audit and feedback is a widely used quality improvement intervention but effects on clinical practice are variable, suggesting potential for enhancement. Behavioural theory, theoretical frameworks of behaviour change and behaviour change techniques provide systematic processes to enhance intervention. This study is part of a larger programme of work to promote the uptake of evidence-based transfusion practice. Objectives: The objectives of this study are to design two theoretically enhanced audit and feedback interventions; one focused on content and one on delivery, and investigate the feasibility and acceptability. Methods: Study A (Content): A coding framework based on current evidence regarding audit and feedback, and behaviour change theory and frameworks will be developed and applied as part of a structured content analysis to specify the key components of existing feedback documents. Prototype feedback documents with enhanced content and also a protocol, describing principles for enhancing feedback content, will be developed. Study B (Delivery): Individual semi-structured interviews with healthcare professionals and observations of team meetings in four hospitals will be used to specify, and identify views about, current audit and feedback practice. Interviews will be based on a topic guide developed using the Theoretical Domains Framework and the Consolidated Framework for Implementation Research. Analysis of transcripts based on these frameworks will form the evidence base for developing a protocol describing an enhanced intervention that focuses on feedback delivery. Study C (Feasibility and Acceptability): Enhanced interventions will be piloted in four hospitals. Semi-structured interviews, questionnaires and observations will be used to assess feasibility and acceptability. Discussion: This intervention development work reflects the UK Medical Research Council’s guidance on development of complex interventions, which emphasises the importance of a robust theoretical basis for intervention design and recommends systematic assessment of feasibility and acceptability prior to taking interventions to evaluation in a full-scale randomised study. The work-up includes specification of current practice so that, in the trials to be conducted later in this programme, there will be a clear distinction between the control (usual practice) conditions and the interventions to be evaluated

Rare missense variants in Tropomyosin-4 (TPM4) are associated with platelet dysfunction, cytoskeletal defects, and excessive bleeding

Background: A significant challenge is faced for the genetic diagnosis of inherited platelet disorders in which candidate genetic variants can be found in more than 100 bleeding, thrombotic, and platelet disorder genes, especially within families in which there are both normal and low platelet counts. Genetic variants of unknown clinical significance (VUS) are found in a significant proportion of such patients in which functional studies are required to prove pathogenicity. Objective: To identify the genetic cause in patients with a suspected platelet disorder and subsequently perform a detailed functional analysis of the candidate genetic variants found. Methods: Genetic and functional studies were undertaken in three patients in two unrelated families with a suspected platelet disorder and excessive bleeding. A targeted gene panel of previously known bleeding and platelet genes was used to identify plausible genetic variants. Deep platelet phenotyping was performed using platelet spreading analysis, transmission electron microscopy, immunofluorescence, and platelet function testing using lumiaggregometry and flow cytometry. Results: We report rare conserved missense variants (p.R182C and p.A183V) in TPM4 encoding tromomyosin-4 in 3 patients. Deep platelet phenotyping studies revealed similar platelet function defects across the 3 patients including reduced platelet secretion, and aggregation and spreading defects suggesting that TPM4 missense variants impact platelet function and show a disordered pattern of tropomyosin staining. Conclusions: Genetic and functional TPM4 defects are reported making TPM4 a diagnostic grade tier 1 gene and highlights the importance of including TPM4 in diagnostic genetic screening for patients with significant bleeding and undiagnosed platelet disorders, particularly for those with a normal platelet count