A Scan of Pleiotropic Immune Mediated Disease Genes Identifies Novel Determinants of Baseline FVIII Inhibitor Status in Hemophilia-A.

Hemophilia-A (HA) is caused by heterogeneous loss-of-function factor (F)VIII gene (F8)-mutations and deficiencies in plasma-FVIII-activity that impair intrinsic-pathway-mediated coagulation-amplification. The standard-of-care for severe-HA-patients is regular infusions of therapeutic-FVIII-proteins (tFVIIIs) but ~30% develop neutralizing-tFVIII-antibodies called "FVIII-inhibitors (FEIs)" and become refractory. We used the PATH study and ImmunoChip to scan immune-mediated-disease (IMD)-genes for novel and/or replicated genomic-sequence-variations associated with baseline-FEI-status while accounting for non-independence of data due to genetic-relatedness and F8-mutational-heterogeneity. The baseline-FEI-status of 450 North American PATH subjects-206 with black-African-ancestry and 244 with white-European-ancestry-was the dependent variable. The F8-mutation-data and a genetic-relatedness matrix were incorporated into a binary linear-mixed model of genetic association with baseline-FEI-status. We adopted a gene-centric-association-strategy to scan, as candidates, pleiotropic-IMD-genes implicated in the development of either ³2 autoimmune-/autoinflammatory-disorders (AADs) or ³1 AAD and FEIs. Baseline-FEI-status was significantly associated with SNPs assigned to NOS2A (rs117382854; p=3.2E-6) and B3GNT2 (rs10176009; p=5.1E-6), which have functions in anti-microbial-/-tumoral-immunity. Among IMD-genes implicated in FEI-risk previously, we identified strong associations with CTLA4 assigned SNPs (p=2.2E-5). The F8-mutation-effect underlies ~15% of the total heritability for baseline-FEI-status. Additive genetic heritability and SNPs in IMD-genes account for >50% of the patient-specific variability in baseline-FEI-status. Race is a significant determinant independent of F8-mutation-effects and non-F8-genetics.

Evaluation of Anticoagulant Monitoring in Pediatric Patients Receiving Enoxaparin for Treatment of Venous Thrombosis.

OBJECTIVES: A venous thromboembolism (VTE) is a blood clot that occurs secondary to vessel wall injury often from a central line insertion. Enoxaparin is often considered a first-line treatment in pediatrics for VTE due to its favorable kinetic profile. Enoxaparin monitoring for pediatric patients is accomplished through anti-Xa monitoring in which monitoring practices may vary between institutions. The objective of this study is to evaluate covariates in pediatric patients to determine which variables are most likely to be associated with enoxaparin dose changes as a result of anti-Xa monitoring. METHODS: A single center, retrospective chart review was conducted in pediatric patients treated with enoxaparin for VTE over a 10-year period and who were assessed to determine covariates that lead to dose changes based on anti-Xa levels. Secondary outcomes described monitoring patterns at the University of New Mexico Children's Hospital. RESULTS: Sixty-eight patients met inclusion criteria in which results showed that patients aged 2 to 5.9 months (p = 0.026), who had critical care status (p = 0.009), and who were of Native American ethnicity (p = 0.016) were likely to have an enoxaparin dose change at least once during their treatment regimen. The mean number of levels drawn were 7.5 per patient over a 6- to 12-week period, and doses were not frequently changed based on a confirmatory lab draw. However, many doses were adjusted based on the week 1 post-therapeutic level. CONCLUSIONS: Patients of Native American ethnicity, younger than 6 months, and those admitted to the PICU were likely to have dose changes based on anti-Xa levels.

A Distinctive Approach to Venous Thromboembolism Treatment in a Pediatric, Hemodialysis Patient: A Case Report.

Enoxaparin is a low molecular weight heparin (LMWH) that is the mainstay for treatment of pediatric patients with a venous thromboembolism, which provides better compliance compared with the use of unfractionated heparin (UFH) in long-term anticoagulation. Although data are limited in pediatric patients with renal insufficiency, enoxaparin can be used in this population. Data related to its use in hemodialysis (HD) pediatric patients is almost non-existent. A major concern for enoxaparin use in patients with renal insufficiency or for those on HD is bleeding. A few studies in adults showed an increased risk of bleeding, but the risk was similar to that of UFH when the two were compared. This case report describes the use of enoxaparin in an 8-year-old female who is on hemodialysis, without any bleeding or clotting complications. Although systematic trials are needed to support the safety and efficacy of LMWH in pediatric patients with renal dysfunction or on HD, this case will provide limited information for enoxaparin use in this population.

Immunodeficiency and bone marrow failure with mosaic and germline TLR8 gain of function.

Inborn errors of immunity (IEI) are a genetically heterogeneous group of disorders with a broad clinical spectrum. Identification of molecular and functional bases of these disorders is important for diagnosis, treatment, and an understanding of the human immune response. We identified 6 unrelated males with neutropenia, infections, lymphoproliferation, humoral immune defects, and in some cases bone marrow failure associated with 3 different variants in the X-linked gene TLR8, encoding the endosomal Toll-like receptor 8 (TLR8). Interestingly, 5 patients had somatic variants in TLR8 with <30% mosaicism, suggesting a dominant mechanism responsible for the clinical phenotype. Mosaicism was also detected in skin-derived fibroblasts in 3 patients, demonstrating that mutations were not limited to the hematopoietic compartment. All patients had refractory chronic neutropenia, and 3 patients underwent allogeneic hematopoietic cell transplantation. All variants conferred gain of function to TLR8 protein, and immune phenotyping demonstrated a proinflammatory phenotype with activated T cells and elevated serum cytokines associated with impaired B-cell maturation. Differentiation of myeloid cells from patient-derived induced pluripotent stem cells demonstrated increased responsiveness to TLR8. Together, these findings demonstrate that gain-of-function variants in TLR8 lead to a novel childhood-onset IEI with lymphoproliferation, neutropenia, infectious susceptibility, B- and T-cell defects, and in some cases, bone marrow failure. Somatic mosaicism is a prominent molecular mechanism of this new disease.

A Cross-Sectional Study of Women and Girls with Congenital Bleeding Disorders: The American Thrombosis and Hemostasis Network Cohort.

Introduction: The number of women and girls (WG) with bleeding disorders cared for at hemophilia treatment centers has increased dramatically over the last 30 years, owing to improved recognition of bleeding symptoms specific to WG. However, basic epidemiologic data of this population remain elusive. The ATHNdataset (American Thrombosis and Hemostasis Network) is a surveillance tool for people with bleeding disorders in the United States, providing demographic as well as bleeding symptom and treatment information. The aim of this study was to characterize the female cohort within the ATHNdataset. Methods: In this retrospective cohort study, the ATHNdataset was queried for demographic data, bleeding disorder diagnosis, bleeding symptoms, and treatment. Descriptive statistics were used. Results: As of December 31, 2017, 8,820 WG with a congenital bleeding disorder were enrolled in the ATHNdataset, comprising 24.5% of the entire ATHNdataset cohort (35,945). The most common reported diagnosis was von Willebrand disease (VWD), accounting for 62.9% of the population. Reproductive tract bleeding was reported in 15.8% of participants older than 15 years. Conclusions: The ATHNdataset describes the largest cohort of WG with bleeding disorders to date. VWD is the most common diagnosis in WG with bleeding disorders. Symptoms specific to WG, such as heavy menstrual bleeding, are underreported in this data set compared with other data sources. Ongoing efforts are needed to improve diagnosis, treatment, and surveillance of WG with bleeding disorders.

Combined alpha-delta platelet storage pool deficiency is associated with mutations in GFI1B.

Combined alpha-delta platelet storage pool deficiency is characterized by the absence or reduction in the number of both alpha granules and dense bodies. This disorder can have variable severity as well as a variable inheritance pattern. We describe two patients from unrelated families with combined alpha-delta storage pool deficiency due to mutations in GFI1B, a zinc finger protein known to act as a transcriptional repressor of various genes. We demonstrate that this disease is associated with either a heterozygous mutation (de novo or familial) abrogating the binding of the zinc fingers with the promoter of its target genes, or by hypomorphic biallelic mutations in GFI1B leading to autosomal recessive inheritance.

PGM3 mutations cause a congenital disorder of glycosylation with severe immunodeficiency and skeletal dysplasia.

Human phosphoglucomutase 3 (PGM3) catalyzes the conversion of N-acetyl-glucosamine (GlcNAc)-6-phosphate into GlcNAc-1-phosphate during the synthesis of uridine diphosphate (UDP)-GlcNAc, a sugar nucleotide critical to multiple glycosylation pathways. We identified three unrelated children with recurrent infections, congenital leukopenia including neutropenia, B and T cell lymphopenia, and progression to bone marrow failure. Whole-exome sequencing demonstrated deleterious mutations in PGM3 in all three subjects, delineating their disease to be due to an unsuspected congenital disorder of glycosylation (CDG). Functional studies of the disease-associated PGM3 variants in E. coli cells demonstrated reduced PGM3 activity for all mutants tested. Two of the three children had skeletal anomalies resembling Desbuquois dysplasia: short stature, brachydactyly, dysmorphic facial features, and intellectual disability. However, these additional features were absent in the third child, showing the clinical variability of the disease. Two children received hematopoietic stem cell transplantation of cord blood and bone marrow from matched related donors; both had successful engraftment and correction of neutropenia and lymphopenia. We define PGM3-CDG as a treatable immunodeficiency, document the power of whole-exome sequencing in gene discoveries for rare disorders, and illustrate the utility of genomic analyses in studying combined and variable phenotypes.

Congenital and childhood myeloproliferative disorders with eosinophilia responsive to imatinib.

Eosinophilia is seen in several myeloproliferative disorders (MPD). A subset of MPD involves the platelet-derived growth factor receptor beta (PDGFRB) gene. Imatinib mesylate has been efficacious in treating some of these MPDs. Here we describe two patients with MPD with eosinophilia and PDGFRB rearrangements, one of which was congenital. Both patients were treated with single agent imatinib and continue to be in clinical, hematologic, and cytogenetic remission despite weaning doses. No definite guidelines currently exist regarding the exact dosing and duration of imatinib therapy for these patients.

Hypoxia-inducible factor-1-regulated protein expression and oligodendroglioma patient outcome: comparison with established biomarkers and preoperative UCSF low-grade scoring system.

Methods for predicting outcome for patients with oligodendrogliomas and anaplastic oligodendrogliomas (AOs) are limited. Hypoxia-inducible factor-1α (HIF-1α) controls many proteins involved in glycolysis and angiogenesis including VEGF, Glut-1, and CA-IX. We examined whether expression of HIF-1α and other hypoxia-regulated molecules (HRM) can predict overall (OS) and progression-free (PFS) survival. We correlated these data with more established biomarkers and a published preoperative scoring system. We prospectively collected tissue samples and followed outcomes of 50 patients with oligodendrogliomas and 32 with AOs. Tumor tissues were stained for measures of proliferative index, microvascular density, IDH-1 mutational status, and HRMs. We retrospectively analyzed preoperative imaging and clinical data based on the UCSF Scoring System (good prognostic indicators: Karnofsky Performance Scale (KPS) score > 80, age < 50 years, tumor diameter < 4 cm, noneloquent tumor location) and correlated these with immunohistochemical markers, 1p19q chromosomal status, and compared both with patient PFS and OS. Mean follow-up was 85.6 ± 41.4 months. HRMs showed higher expression in AOs than in oligodendrogliomas. Both 1p19q codeletion and IDH-1 mutation predict outcome of patients with both oligodendroglioma and AO. The UCSF score is a strong predictor for oligodendrogliomas patient outcome and is strengthened by IDH-1 and 1p19q status. Glut-1 may be useful in predicting PFS in AOs. Proliferation index >5 for oligodendrogliomas and KPS ≤ 80 for AOs predict a worse prognosis. Immunohistochemical markers of HRMs show a significantly higher expression in anaplastic variants of oligodendrogliomas and may contribute to the prediction of survival in these patients.

Staying on message: design principles for controlling nonspecific responses to siRNA.

Short interfering RNAs (siRNA) are routinely used in the laboratory to induce targeted gene silencing by RNA interference, and increasingly, this technology is being translated to the clinic. However, there are multiple mechanisms by which siRNA may be recognized by receptors of the innate immune system, including both endosomal Toll-like receptors and cytoplasmic receptors. Signaling through these receptors may induce multiple nonspecific effects, including general reductions in gene expression and the production of type I interferons and inflammatory cytokines, which can lead to systemic inflammation in vivo. The pattern of immune activation varies depending upon the types of cells and receptors that are stimulated by a particular siRNA. Although we are still discovering the mechanisms by which these recognition events occur, our current understanding provides useful guidelines for avoiding immune activation. In this minireview, we present a design-based approach for developing siRNA-based experiments and therapies that evade innate immune recognition and control nonspecific effects. We describe strategies and trade-offs related to siRNA design considerations including the choice of siRNA target sequence, chemical modifications to the RNA backbone and the influence of the delivery method on immune activation. Finally, we provide suggestions for conducting appropriate controls for siRNA experiments, because some commonly employed strategies do not adequately account for known nonspecific effects and can lead to misinterpretation of the data. By incorporating these principles into siRNA design, it is generally possible to control nonspecific effects, and doing so will help to best utilize this powerful technology for both basic science and therapeutics.