Patterns of bruising in preschool children with inherited bleeding disorders: a longitudinal study

Objective The extent that inherited bleeding disorders affect; number, size and location of bruises in young children <6 years. Design Prospective, longitudinal, observational study. Setting Community. Patients 105 children with bleeding disorders, were compared with 328 without a bleeding disorder and classified by mobility: premobile (non-rolling/rolling over/ sitting), early mobile (crawling/cruising) and walking and by disease severity: severe bleeding disorder factor VIII/IX/XI <1 IU/dL or type 3 von Willebrand disease. Interventions Number, size and location of bruises recorded in each child weekly for up to 12 weeks. Outcomes The interventions were compared between children with severe and mild/moderate bleeding disorders and those without bleeding disorders. Multiple collections for individual children were analysed by multilevel modelling. Results Children with bleeding disorders had more and larger bruises, especially when premobile. Compared with premobile children without a bleeding disorder; the modelled ratio of means (95% CI) for number of bruises/ collection was 31.82 (8.39 to 65.42) for severe bleeding disorders and 5.15 (1.23 to 11.17) for mild/moderate, and was 1.81 (1.13 to 2.23) for size of bruises. Children with bleeding disorders rarely had bruises on the ears, neck, cheeks, eyes or genitalia. Conclusions Children with bleeding disorder have more and larger bruises at all developmental stages. The differences were greatest in premobile children. In this age group for children with unexplained bruising, it is essential that coagulation studies are done early to avoid the erroneous diagnosis of physical abuse when the child actually has a serious bleeding disorder, however a blood test compatible with a mild/moderate bleeding disorder cannot be assumed to be the cause of bruising

Estimating and interpreting individual patients' pharmacokinetic profiles in persons with Hemophilia A or B using a population pharmacokinetic approach: communication from the SSC of the ISTH

The ISTH SSC on Factor VIII/IX has previously issued guidelines for studies assessing the pharmacokinetics (PK) of factor concentrates [1,2]. They suggested drawing 10 or 11 blood samples over a period of 32-48h or 50-72h, after infusing 25-50 or 50-75 IU/kg, respectively for factor VIII (FVIII) or factor IX (FIX), in cohorts of 12-15 patients with a crossover design. Such PK studies are not ideal for tailoring the treatment of individual patients, mostly for the requirement of several blood samples. Due to broad inter-individual variation, the individual disposition of FVIII and FIX cannot be predicted from morphometric characteristics and average PK parameters, but requires empirical assessment in each individual [3–6]. Previous guidance of this ISTH SSC described the PK methodology for the prediction of individual trough levels of FVIII [7]. The present communication, building on recent advancements in the population PK (PopPK) of FVIII and FIX [8], adds to the former documents

Comparison of Magnetic Resonance Imaging Scales for Assessment of Interval Changes of Arthropathy in Boys with Severe Hemophilia

Background/Objectives: The variety of magnetic resonance imaging (MRI) scales available to measure soft tissue and osteochondral changes in joints of persons with hemophilia poses challenges in evaluating published clinical/research studies. To evaluate the value of four MRI scales [(i) the 17-point International Prophylaxis Study Group [IPSG] additive scale; (ii) and (iii) the compatible IPSG progressive (P) and additive (A) scales; and (iv) the Denver progressive scale] to assess joint change in boys with hemophilia participating in a prospective two-year prophylaxis study. Methods: Boys with severe hemophilia A (ages, 7&ndash;16 years) followed at the Hospital for Sick Children, Toronto, Canada had MRI evaluations of six index joints (ankles, knees, elbows) at study entry and exit. Musculoskeletal (MSK) outcomes included in the study were the Colorado Child Physical Examination (PE) scale; the Pettersson (X-ray) scale; and the aforementioned 4 MRI scales. Results: Very strong (r &ge; 0.80) correlations were observed between the IPSG 17-point, the IPSG progressive (P) and the Denver MRI scales, and moderate (r = 0.40&ndash;0.59) to strong (r = 0.60&ndash;0.79) correlations for the IPSG 17 point and the IPSG additive (A) MRI scales. Very weak (r = 0.20&ndash;0.39) or no correlations were observed between soft tissue MRI scores and the swelling item of the Child PE scale. Conclusions: All four MRI scales demonstrated relative comparability of their construct validities for assessing mild/moderate hemophilic arthropathy. The 17-point IPSG additive scale is recommended as a reference standard in future long-term studies of young boys with hemophilia receiving factor and non-factor-based preventive therapies

Clinical outcomes in hemophilia: Towards development of a core set of standardized outcome measures for research

Introduction: A lack of uniformity in the choice of outcome measurement in hemophilia care and research has led to studies with incomparable results. We identified a need to define core outcome measures for use in research and clinical care of persons with hemophilia. Objective: To move toward a core set of outcome measures for the assessment of persons with hemophilia in research and practice. Methods: A modified nominal groups process was conducted with an international group of hemophilia experts, including persons with hemophilia as follows. Step 1: item generation for all potential outcome measures. Step 2: survey where respondents voted on the relative importance and usefulness of each item. Steps 3/4: 2-day meeting where attendees voted for items they valued, followed by open discussion and a second round of voting. Step 5: survey where respondents selected their top five items from those with >50% agreement at the meeting. Results: The highest ranked items for the pediatric core set (% agreement) are treatment satisfaction (92.7%), joint health (83.3%), a measure of access to treatment (82.5%), a measure of treatment adherence (72.5%), and generic performance based physical function (72.1%). The highest ranked items for the adult core set (% agreement) are total bleeding events (88.1%), EuroQol five dimensions (85.4%), treatment adherence (82.1%), joint health (79.1%), and number/location of bleeds per unit time (78.6%). Conclusion: This process generated a list of preferred outcome measures to consider for assessment in persons with hemophilia. This information now requires refinement to define optimal core sets for use in different clinical/research contexts

Modeling to predict factor VIII levels associated with zero bleeds in patients with severe hemophilia A initiated on tertiary prophylaxis

Background Factor VIII (FVIII) trough levels > 1 IU/dL in patients with severe hemophilia A receiving regular prophylaxis may optimize bleed protection. Objectives In this post hoc analysis of patients receiving tertiary prophylaxis for approximately 1 year, the relationship between estimated FVIII levels and reported bleeds was investigated to predict the potential for zero bleeds. Methods Sixty-three patients (median [range] age, 28 [7–59] years) with severe hemophilia A (229 bleeds) were included. FVIII levels at time of each bleed were estimated from single-dose individual pharmacokinetics. The highest estimated FVIII level at which patients experienced a bleed was considered the “potentially effective trough level” for that bleed type. Kaplan–Meier estimates of proportions of patients with no bleeds above certain estimated FVIII levels were determined. Those not experiencing a bleed in the trial were assumed to have a bleed at 0 IU/dL (pragmatic approach) or at their median trough level (conservative approach). Results Kaplan–Meier estimates based on pragmatic approach predicted zero all bleeds, joint bleeds, and spontaneous joint bleeds in 1 year in 40, 43, and 63% of patients, respectively, when the potentially effective trough FVIII level was set at 1 IU/dL. Between 1 and 10 IU/dL, every 1 IU/dL rise in estimated FVIII level was associated with an additional 2% of patients having zero all bleeds. Conclusion This post hoc analysis confirms benefits with trough levels of approximately 1 to 3 IU/dL in most patients starting tertiary prophylaxis; prophylaxis with higher trough levels may help patients to achieve zero bleeds

Measuring disease-specific quality of life in rare populations: a practical approach to cross-cultural translation

<p>Abstract</p> <p>Background</p> <p>Disease-specific quality of life (QoL) measures have enhanced the capacity of outcome measures to evaluate subtle changes and differences between groups. However, when the specific disease is rare, the cohort of patients is small and international collaboration is often necessary to accomplish meaningful research. As many of the QoL measures have been developed in North American English, they require translation to ensure their usefulness in a multi-cultural and/or international society. Published guidelines provide formal methods to achieve cross-culturally comparable versions of a QoL tool. However, these guidelines describe a rigorous process that is not always feasible, particularly in rare disease groups. The objective of this manuscript is to describe the process that was developed to achieve accurate cross-cultural translations of a disease-specific QoL measure, to overcome the challenges of a small sample size, i.e. children with a rare disorder.</p> <p>Procedure</p> <p>A measurement study was conducted in the United Kingdom (UK), France, Germany and Uruguay, during which the validated measure was translated into the languages of the respective countries.</p> <p>Results</p> <p>This is a report of a modified, child-centric, cross-cultural translation and adaptation process in which culturally appropriate and methodologically valid translations of a disease-specific QoL measure, the Kids' ITP Tools (KIT), were performed in children with immune thrombocytopenic purpura (ITP). The KIT was translated from North American English into UK English, French, German, and Spanish.</p> <p>Conclusion</p> <p>This study was a successful international collaboration. The modified process through which culturally appropriate and methodologically valid translations of QoL measures may be achieved in a pediatric population with a relatively rare disorder is reported.</p

Transduction of rat pancreatic islets with pseudotyped adeno-associated virus vectors

<p>Abstract</p> <p>Background</p> <p>Pancreatic islet transplantation is a promising treatment for type I diabetes mellitus, but current immunosuppressive strategies do not consistently provide long-term survival of transplanted islets. We are therefore investigating the use of adeno-associated viruses (AAVs) as gene therapy vectors to transduce rat islets with immunosuppressive genes prior to transplantation into diabetic mice.</p> <p>Results</p> <p>We compared the transduction efficiency of AAV2 vectors with an AAV2 capsid (AAV2/2) to AAV2 vectors pseudotyped with AAV5 (AAV2/5), AAV8 (AAV2/8) or bovine adeno-associated virus (BAAV) capsids, or an AAV2 capsid with an insertion of the low density lipoprotein receptor ligand from apolipoprotein E (AAV2apoE), on cultured islets, in the presence of helper adenovirus infection to speed expression of a GFP transgene. Confocal microscopy and flow cytometry were used. The AAV2/5 vector was superior to AAV2/2 and AAV2/8 in rat islets. Flow cytometry indicated AAV2/5-mediated gene expression in approximately 9% of rat islet cells and almost 12% of insulin-positive cells. The AAV2/8 vector had a higher dependence on the helper virus multiplicity of infection than the AAV 2/5 vector. In addition, the BAAV and AAV2apoE vectors were superior to AAV2/2 for transducing rat islets. Rat islets (300 per mouse) transduced with an AAV2/5 vector harboring the immunosuppressive transgene, <it>tgfβ1</it>, retain the ability to correct hyperglycemia when transplanted into immune-deficient diabetic mice.</p> <p>Conclusion</p> <p>AAV2/5 vectors may therefore be useful for pre-treating donor islets prior to transplantation.</p

Novel Corrector for Variants of SLC6A8: A Therapeutic Opportunity for Creatine Transporter Deficiency

Mutations in creatine transporter SLC6A8 cause creatine transporter deficiency (CTD), which is responsible for 2% of all cases of X-linked intellectual disability. CTD has no current treatments and has a high unmet medical need. Inspired by the transformational therapeutic impact of small molecule "correctors" for the treatment of cystic fibrosis, which bind to mutated versions of the CFTR ion channel to promote its trafficking to the cell surface, we sought to identify small molecules that could stabilize SLC6A8 as a potential treatment for CTD. We leveraged a novel chemoproteomic technology for ligand discovery, reactive affinity probe interaction discovery, to identify small-molecule fragments with photoaffinity handles that bind to SLC6A8 in a cellular environment. We synthesized a library of irreversible covalent analogs of these molecules to characterize in functional assays, which revealed molecules that could promote the trafficking of mutant SLC6A8 variants to the cell surface. Further medicinal chemistry was able to identify reversible drug-like small molecules that both promoted trafficking of the transporter and also rescued creatine uptake. When profiled across the 27 most prevalent SLC6A8 missense variants, we found that 10-20% of patient mutations were amenable to correction by our molecules. These results were verified in an endogenous setting using the CRISPR knock-in of selected missense alleles. We established in vivo proof-of-mechanism for correctors in a novel CTD mouse model with the P544L patient-defined variant knocked in to the SLC6A8 locus, where treatment with our orally bioavailable and brain penetrant tool corrector increased brain creatine levels in heterozygous female mice, validating correctors as a potential therapeutic approach for CTD

Robustness of Ancestral Sequence Reconstruction to Phylogenetic Uncertainty

Ancestral sequence reconstruction (ASR) is widely used to formulate and test hypotheses about the sequences, functions, and structures of ancient genes. Ancestral sequences are usually inferred from an alignment of extant sequences using a maximum likelihood (ML) phylogenetic algorithm, which calculates the most likely ancestral sequence assuming a probabilistic model of sequence evolution and a specific phylogeny—typically the tree with the ML. The true phylogeny is seldom known with certainty, however. ML methods ignore this uncertainty, whereas Bayesian methods incorporate it by integrating the likelihood of each ancestral state over a distribution of possible trees. It is not known whether Bayesian approaches to phylogenetic uncertainty improve the accuracy of inferred ancestral sequences. Here, we use simulation-based experiments under both simplified and empirically derived conditions to compare the accuracy of ASR carried out using ML and Bayesian approaches. We show that incorporating phylogenetic uncertainty by integrating over topologies very rarely changes the inferred ancestral state and does not improve the accuracy of the reconstructed ancestral sequence. Ancestral state reconstructions are robust to uncertainty about the underlying tree because the conditions that produce phylogenetic uncertainty also make the ancestral state identical across plausible trees; conversely, the conditions under which different phylogenies yield different inferred ancestral states produce little or no ambiguity about the true phylogeny. Our results suggest that ML can produce accurate ASRs, even in the face of phylogenetic uncertainty. Using Bayesian integration to incorporate this uncertainty is neither necessary nor beneficial