The switch from fetal to adult hemoglobin expression in humans is related to the active repression of HbF expression by
BCL11A
. A self-inactivating lentivirus vector with a short hairpin RNA ...designed to interfere with
BCL11A
expression was inserted into autologous hematopoietic stem cells of patients with sickle cell disease, resulting in increased expression of HbF and a decline in the frequency of sickle cell crises.
Iron deficiency is usually attributed to chronic blood loss or inadequate dietary intake. Here, we show that iron deficiency anemia refractory to oral iron therapy can be caused by germline mutations ...in TMPRSS6, which encodes a type II transmembrane serine protease produced by the liver that regulates the expression of the systemic iron regulatory hormone hepcidin. These findings demonstrate that TMPRSS6 is essential for normal systemic iron homeostasis in humans.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Iron deficiency anemia is a common global problem whose etiology is typically attributed to acquired inadequate dietary intake and/or chronic blood loss. However, in several kindreds multiple family ...members are affected with iron deficiency anemia that is unresponsive to oral iron supplementation and only partially responsive to parenteral iron therapy. The discovery that many of these cases harbor mutations in the TMPRSS6 gene led to the recognition that they represent a single clinical entity: iron-refractory iron deficiency anemia (IRIDA). This article reviews clinical features of IRIDA, recent genetic studies, and insights this disorder provides into the regulation of systemic iron homeostasis.
Reducing expression of the fetal hemoglobin (HbF) repressor BCL11A leads to a simultaneous increase in γ-globin expression and reduction in β-globin expression. Thus, there is interest in targeting ...BCL11A as a treatment for β-hemoglobinopathies, including sickle cell disease (SCD) and β-thalassemia. Here, we found that using optimized shRNAs embedded within an miRNA (shRNAmiR) architecture to achieve ubiquitous knockdown of BCL11A profoundly impaired long-term engraftment of both human and mouse hematopoietic stem cells (HSCs) despite a reduction in nonspecific cellular toxicities. BCL11A knockdown was associated with a substantial increase in S/G2-phase human HSCs after engraftment into immunodeficient (NSG) mice, a phenotype that is associated with HSC exhaustion. Lineage-specific, shRNAmiR-mediated suppression of BCL11A in erythroid cells led to stable long-term engraftment of gene-modified cells. Transduced primary normal or SCD human HSCs expressing the lineage-specific BCL11A shRNAmiR gave rise to erythroid cells with up to 90% reduction of BCL11A protein. These erythrocytes demonstrated 60%-70% γ-chain expression (vs. < 10% for negative control) and a corresponding increase in HbF. Transplantation of gene-modified murine HSCs from Berkeley sickle cell mice led to a substantial improvement of sickle-associated hemolytic anemia and reticulocytosis, key pathophysiological biomarkers of SCD. These data form the basis for a clinical trial application for treating sickle cell disease.
Red blood cell transfusions have become standard of care for the prevention of life‐threatening anemia in patients with β‐thalassemia and sickle cell disease (SCD). However, frequent transfusions can ...lead to accumulation of iron that can result in liver cirrhosis, diabetes mellitus, arthritis, arrhythmias, cardiomyopathy, heart failure, and hypogonadotropic hypogonadism. Iron chelation therapy has been shown to reduce serum ferritin levels and liver iron content, but limitations of trial design have prevented any demonstration of improved survival. The objective of this systematic review was to investigate the impact of iron chelation therapy on overall and event‐free survival in patients with β‐thalassemia and SCD. Eighteen articles discussing survival in β‐thalassemia and 3 in SCD were identified. Overall iron chelation therapy resulted in better overall survival, especially if it is instituted early and compliance is maintained. Comparative studies did not show any significant differences between available iron chelation agents, although there is evidence that deferiprone is better tolerated than deferoxamine and that compliance is more readily maintained with the newer oral drugs, deferiprone and deferasirox. Iron chelation therapy, particularly the second‐generation oral agents, appears to be associated with improved overall and event‐free survival in transfusion‐dependent patients with β‐thalassemia and patients with SCD.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The Stroke With Transfusions Changing to Hydroxyurea (SWiTCH) trial compared standard (transfusions/chelation) to alternative (hydroxyurea/phlebotomy) treatment to prevent recurrent stroke and manage ...iron overload in children chronically transfused over 7 years before enrollment. Standardized brain magnetic resonance imaging/magnetic resonance angiography (MRA) and transcranial Doppler (TCD) exams were performed at entry and exit, with a central blinded review. A novel MRA vasculopathy grading scale demonstrated frequent severe baseline left/right vessel stenosis (53%/41% ≥Grade 4); 31% had no vessel stenosis on either side. Baseline parenchymal injury was prevalent (85%/79% subcortical, 53%/37% cortical, 50%/35% subcortical and cortical). Most children had low or uninterpretable baseline middle cerebral artery TCD velocities, which were associated with worse stenoses (incidence risk ratio IRR = 5.1, P ≤ .0001 and IRR = 4.1, P < .0001) than normal velocities; only 2% to 12% had any conditional/abnormal velocity. Patients with adjudicated stroke (7) and transient ischemic attacks (19 in 11 standard/8 alternative arm subjects) had substantial parenchymal injury/vessel stenosis. At exit, 1 child (alternative arm) had a new silent infarct, and another had worse stenosis. SWiTCH neuroimaging data document severe parenchymal and vascular abnormalities in children with SCA and stroke and support concerns about chronic transfusions lacking effectiveness for preventing progressive cerebrovascular injury. The novel SWiTCH vasculopathy grading scale warrants validation testing and consideration for use in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00122980.
•Children with SCA and stroke show severe parenchymal and vascular abnormalities that can be assessed using a vasculopathy grading scale.•Results from the SWiTCH Trial support concerns about ineffectiveness of transfusion therapy in preventing cerebrovascular injury progression.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background
Typical sickle cell disease (SCD) vaso‐occlusive pain episode (VOE) management includes opioids, which are often inadequate and can be associated with significant side effects. Ketamine, a ...dissociative anesthetic, is a potentially effective adjunct to VOE management.
Objectives
This study aimed to characterize ketamine use for VOE management in pediatric SCD.
Method
This retrospective case series summarizes a single‐center experience regarding the use of ketamine for inpatient management of pediatric VOE in 156 admissions from 2014 to 2020.
Results
Continuous low‐dose ketamine infusion was most commonly prescribed to adolescents and young adults as an adjunct to opioids (median starting dose 2.0 μg/kg/min; median maximum dose 3.0 μg/kg/min). Ketamine was started a median of 13.7 hours after admission. Median ketamine infusion duration was 3 days. In most encounters, ketamine infusion was discontinued prior to opioid patient‐controlled analgesia (PCA) discontinuation. The majority of encounters (79.3%) had a reduction in either PCA dose, continuous opioid infusion, or both while receiving ketamine. Low‐dose ketamine infusion was associated with side effects noted in 21.8% (n = 34) of encounters. The most common side effects included dizziness (5.6%), hallucinations (5.1%), dissociation (2.6%), and sedation (1.9%). There were no reports of ketamine withdrawal. Most patients who received ketamine went on to receive it again during a subsequent admission.
Conclusion
Further study is needed to determine the optimal timing of ketamine initiation and dosing. The variability of ketamine administration highlights the need for standardized protocols for ketamine use in VOE management.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
BACKGROUND
The COVID-19 vaccine is important for children with sickle cell disease (SCD). This quality improvement project's objective was to increase the proportion of children with SCD receiving ≥2 ...COVID-19 vaccine doses to ≥70% by June 2022.
METHODS
We used the Model for Improvement framework. We assessed COVID-19 vaccination rates biweekly. Three plan-do-study-act cycles focusing on patient education, provider awareness, and access were performed. Process measures included the outcome of outreach calls and educational video views. Missed clinic appointments was our balancing measure. Line graphs and statistical process control charts were used to track changes. Interrupted time series was used to model implementation rates while accounting for preexisting trends.
RESULTS
A total of 243 patients were included. During the preintervention (September 2021–January 2022) and intervention periods (February 2022–June 2022), overall vaccination rates increased from 33% to 41% and 41% to 64%, respectively. Mean vaccination rate in eligible children in each 2-week period increased from 2.1% to 7.2%. The achieved vaccination rate was 11% greater than predicted for patients with SCD. For the general population the achieved vaccination rate was 23% lower than predicted. The proportion of missed visits did not change (9.0% vs. 9.6%). During outreach calls, 10 patients (13.5%) booked a vaccine. Forty percent of patients watched the promotional video.
CONCLUSIONS
A significant number of patients with SCD are not vaccinated against COVID-19. Targeting misinformation and improving vaccine access aided in increasing vaccination. Additional interventions are needed as a large number of patients remain unvaccinated.
The integration of genomic testing into clinical care enables the use of individualized approaches to the management of rare diseases. We describe the use of belzutifan, a potent and selective ...small-molecule inhibitor of the protein hypoxia-inducible factor 2α (HIF2α), in a patient with polycythemia and multiple paragangliomas (the Pacak–Zhuang syndrome). The syndrome was caused in this patient by somatic mosaicism for an activating mutation in
EPAS1
. Treatment with belzutifan led to a rapid and sustained tumor response along with resolution of hypertension, headaches, and long-standing polycythemia. This case shows the application of a targeted therapy for the treatment of a patient with a rare tumor-predisposition syndrome. (Funded by the Morin Family Fund for Pediatric Cancer and Alex’s Lemonade Stand Foundation.)
Pacak–Zhuang syndrome is an inherited tumor-predisposition disorder characterized by polycythemia and paragangliomas. A patient with this disorder had polycythemia, headache, hypertension, and norepinephrine-secreting paragangliomas. She had activating mutations in
HIF2A
. Use of belzutifan, a HIF2α inhibitor, led to paraganglioma regression, normalized hemoglobin levels, and symptom resolution.
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