HbF Levels Research Articles

Base editing of key residues in the BCL11A-XL-specific zinc finger domains derepresses fetal globin expression

BCL11A-XL directly binds and represses the γ-globin (HBG1/2) gene promoters, using three Zinc-Finger domains (ZnF4, ZnF5, ZnF6), and is a potential target for β-hemoglobinopathy treatments. Disrupting BCL11A-XL results in de-repression of fetal globin and high HbF, but also affects Hematopoietic Stem and Progenitor Cells (HSPC) engraftment and erythroid maturation. Intriguingly, neurodevelopmental patients with ZnF domain mutations have elevated HbF with normal hematological parameters. Inspired by this natural phenomenon, we employed both CRISPR/Cas9 and base editing at specific ZnF domains and assessed the impacts on HbF production and hematopoietic differentiation. Generating indels in the various ZnF domains by CRISPR/Cas9 prevented the binding of BCL11A-XL to its site in the HBG1/2 promoters and the elevated HbF levels but impacted normal hematopoiesis. Far fewer side effects were observed with base editing, for instance, erythroid maturation in vitro was near normal. However, we observed a modest reduction in HSPC engraftment and a complete loss of B-cell development in vivo, presumably because current base editing is not capable of precisely recapitulating the mutations found in patients with BCL11A-XL associated neurodevelopment disorders. Overall, our results reveal that disrupting different ZnF domains has different impacts. Disrupting ZnF4 elevated HbF levels significantly, while leaving many other erythroid target genes unaffected, and interestingly, disrupting ZnF6 also elevated HbF levels, which was unexpected as this region does not directly interact with the HBG1/2 promoters. This first structure/function analysis of ZnF4-6 provides important insights into the domains of BCL11A-XL required to repress γ-globin expression and provides a framework for exploring the introduction of natural mutations that may enable de-repression of single genes while leaving other functions unaffected.

A comparative evaluation of the analytical performances of premier resolution-high-performance liquid chromatography (PR-HPLC) with capillary zone electrophoresis (CZE) assays for the detection of hemoglobin variants and the quantitation of HbA0, A2, E, and F.

Hemoglobinopathies, including thalassemia and hemoglobin (Hb) variants, are common hematological disorders in tropical countries. Accurate and precise separation of hemoglobin types and reliable quantitation are necessary for differential diagnosis of these disorders. We have evaluated the analytical performances of premier resolution-high-performance liquid chromatography (PR-HPLC; Trinity Biotech, Co. Wicklow, Ireland) to assist in the presumptive diagnosis of thalassemia and Hb variants commonly found in Southeast Asian countries. HbA0, HbA2, HbE, and HbF levels were separated and quantified in 120 blood samples from unrelated adult subjects and compared with those analyzed by capillary zone electrophoresis (CZE; CAPILLARYS™ 2, Sebia, Norcross, GA, US). The Hb analysis patterns of Hb variants obtained from the PR-HPLC system were also compared to those obtained from HPLC (VARIANT II, β-thalassemia Short Program, Bio-Rad, Laboratories, Hercules, CA, US) and CZE systems. The PR-HPLC had excellent precision with a coefficient of variation (CV) for HbA2 quantitation of 3.8 % within-run and 5.2 % between-run. The levels of HbA2/E quantified by the PR-HPLC system correlated well with those of the CZE system (r=0.997). In addition, thalassemia interpretation results obtained from the PR-HPLC and the CZE showed 100 % agreement. Moreover, chromatograms of the PR-HPLC were also comparable to those of VII-HPLC and CAP2-CZE electropherograms. The PR-HPLC system would be applicable to diagnose common forms of thalassemia and Hb variants in Southeast Asia.

Neurological abnormalities among pediatric patients with sickle cell disease in Saudi Arabia: a single-center retrospective study.

Sickle cell disease (SCD) is a common inherited blood disorder characterized by the production of abnormal sickle-shaped red blood cells. SCD can lead to various complications including neurological issues. Early detection and treatment are crucial for preventing these complications. This study aimed to describe the neurological manifestations, radiological findings, and neurological diagnosis related to SCD in Saudi children with the aim of contributing to the formulation of population-based guidelines for screening and treating SCD-related neurological complications. This descriptive retrospective study included pediatric patients aged < 14 years diagnosed with SCD who were regularly followed up at the hematology clinic in KAMC, Jeddah, Saudi Arabia, from January 2008 to January 2022. Demographic and clinical data were collected from the clinical charts of 101 participants. This study included 101 patients with SCD with a mean age of 23 months at diagnosis. Among these, 59% had SCD and high fetal hemoglobin (HbF) levels. Neurological sequelae, including seizures, stroke, and other abnormalities, were observed in 26.7% of patients. There were no significant differences in the onset of neurological issues between the patients with SCD-high HbF and those with other SCD phenotypes. This study highlights the increased risk of brain injury and neurocognitive deficits in children with SCD. The occurrence of neurological sequelae in many patients emphasizes the need for early detection and intervention. Some patients experience neurological complications despite having high HbF levels, suggesting that further interventions are needed. This study has some limitations, including its small sample size and retrospective nature. Early detection and intervention are crucial for neurological complications in patients with SCD. This study emphasizes the need for further research and effective treatment strategies considering the presence of neurological complications despite the presence of high HbF levels. Large-scale studies and population-specific guidelines are warranted for better understanding and management of SCD-related neurological complications in the Saudi population.

Characterization of a cohort of Angolan children with sickle cell anemia treated with hydroxyurea

BackgroundSickle Cell Anemia (SCA) is a monogenic disease, although its severity and response to treatment are very heterogeneous. ObjectivesThis study aims to characterize a cohort of Angolan children with SCA and evaluate their response to hydroxyurea (HU) treatment and the potential side effects and toxicity. MethodsThe study enrolled 215 patients between 3 and 12 years old before and after the administration of HU, at a fix dose of 20 mg/kg/day for 12 months. ResultsA total of 157 patients started HU medication and 141 of them completed the 12-month treatment. After initiating HU treatment, the frequency of clinical events decreased (transfusions 53.4 %, hospitalizations 47.1 %). The response to HU medication varied among patients, with some experiencing an increase in fetal hemoglobin (HbF) of <5 %. The mean increase in HbF was 11.9 %, ranging from 1.8 % to 31 %. Responders to HU treatment were 57 %, inadequate responders 38.7 % and non-adherent 4.2 %. No clinical side effects related to HU were reported. Hematological toxicities were transient and reversible. Children naïve to HU and with lower HbF reported higher number of hospitalizations caused by malaria infection. During HU treatment, the frequency of malaria episodes did not appear to be affected by HbF levels. Conclusionsthe present study provided a valuable contribution to the understanding of the clinical and laboratory profiles of Angolan children with SCA. These findings support the evidence that the implementation of prophylactic measures and treatment with HU is associated with increased survival in children with SCA.

Peripheral blood circular RNA circ-0008102 may serve as a novel clinical biomarker in beta-thalassemia patients

Circular RNA circ-0008102 has previously been found dysregulated in β-thalassemia (β-thal) in circRNAs microarray (GSE196682 and GSE241141). Our study is aimed at identifying whether circ-0008102 could be a novel biomarker in β-thal. The peripheral blood of pediatric β-thal patients with (n = 39) or without (n = 20) blood transfusion and healthy controls (n = 30) was selected. qRT-PCR, ROC curve analysis, Spearman correlation analysis, and FISH were used to analyze clinical value of circ-0008102. qRT-PCR confirmed that circ-0008102 expression in pediatric β-thal patients without blood transfusion was significantly higher. ROC curves analysis showed that the AUC of circ-0008102 for differentiating patients without blood transfusion from patients with blood transfusion and healthy controls with an AUC of 0.733 and 0.711. Furthermore, circ-0008102 expression was positively correlated with the levels of RBC, HbF, β-globin, and γ-globin mRNA, but was negatively corrected with the levels of HbA and Cr. circ-0008102 was mainly located in the cytoplasm. circ-0008102 could induce the activation of γ-globin and negatively regulate the expression of the five highest-ranking candidate miRNAs (miR-372-3p, miR-329-5p, miR-198, miR-152-5p, and miR-627-3p) in K562 cells.Conclusion: We demonstrate that peripheral blood upregulated circ-0008102 may serve as a novel clinical biomarker for pediatric β-thal without blood transfusion.What is known:• CircRNAs are known to be involved in various human diseases, and several circRNAs are regarded as a class of promising blood-based biomarkers for detection of β-thal.• CircRNAs exert biological functions by epigenetic modification and gene expression regulation, and dysregulated circRNAs in β-thal might be involved in the induction of HbF in β-thal.What is new:• Peripheral blood circ-0008102 maybe serve as a novel clinical biomarker for detection of pediatric β-thal without blood transfusion.• Circ-0008102 participates in the pathogenesis of β-thal through regulating γ-globin expression, and negatively regulates the expression of miR-372-3p, miR-329-5p, miR-198, miR-152-5p and miR-627-3p.

Identification and characterization of CHD4-associated eRNA as a novel modulator of fetal hemoglobin levels in β-thalassemia

Fetal-to-adult hemoglobin switching is controlled by programmed silencing of γ-globin while the re-activation of fetal hemoglobin (HbF) is an effective strategy for ameliorating the clinical severity of β-thalassemia and sickle cell disease. The identification of enhancer RNAs (eRNAs) related to the fetal (α2γ2) to adult hemoglobin (α2β2) switching remains incomplete. In this study, the transcriptomes of GYPA+ cells from six β-thalassemia patients with extreme HbF levels were sequenced to identify differences in patterns of noncoding RNA expression. It is interesting that an enhancer upstream of CHD4, an HbF-related core subunit of the NuRD complex, was differentially transcribed. We found a significantly positive correlation of eRNA-CHD4 enhancer-gene interaction using the public database of FANTOM5. Specifically, the eRNA-CHD4 expression was found to be significantly higher in both CD34+ HSPCs and HUDEP-2 than those in K562 cells which commonly expressed high level of HbF, suggesting a correlation between eRNA and HbF expression. Furthermore, prediction of transcription binding sites of cis-eQTLs and the CHD4 genomic region revealed a putative interaction site between rs73264846 and ZNF410, a known transcription factor regulating HbF expression. Moreover, in-vitro validation showed that the inhibition of eRNA could reduce the expression of HBG expression in HUDEP-2 cells. Taken together, the findings of this study demonstrate that a distal enhancer contributes to stage-specific silencing of γ-globin genes through direct modulation of CHD4 expression and provide insights into the epigenetic mechanisms of NuRD-mediated hemoglobin switching.

Sickle Cell Anemia Screening in Newborns and Analysis of Haplotypes in Patients from Santiago Island, Cape Verde.

Sickle cell anemia (SCA) results from a mutation in the β-globin gene, leading to the production of mutant hemoglobin, known as hemoglobin S (HbS). Despite being a genetic disorder, the phenotype of SCA can be influenced by the level of fetal hemoglobin (HbF), which is associated with beta S-globin haplotypes. In this study, we conducted newborn screening (NBS) using samples collected from umbilical cord blood in two hospitals on Santiago Island, Cape Verde. In newborns, HbS was detected using high-performance liquid chromatography (HPLC) on dried blood spot, with confirmation through polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). In addition, we assessed the hematological and clinical characteristics of a second population group consisting of patients diagnosed with SCA. Haplotype determination was performed on both newborns with HbS and patients with SCA. Beta S-globin haplotypes were determined using PCR-RFLP. Hematological values were analyzed using standard methods. Out of 346 newborns, 21 (6%) were carriers of the sickle cell trait (HbAS) while none were identified as homozygous for sickle cell disease (HbSS). Among both groups of individuals, four haplotypes were identified: Senegal, Arabi-Indian, Bantu, and Benin. The Senegal haplotype was the most prevalent, possibly reflecting the ethnic origin of the mutations observed. Hematological values did not differ significantly among haplotypes. However, higher levels of HbF were associated with better hematological values. These findings suggest a positive impact of elevated HbF levels on reducing the severity of SCA. Finally, we demonstrated how the combination of technics, HPLC and molecular analysis, provided a consistent and reproducible results that can be used for NBS for SCA.

Pharmacologic Therapies in Beta Hemoglobinopathies: Fetal Globin Gene Induction in the First Molecular Diseases

Beta hemoglobinopathies and thalassemias are caused by diverse molecular mutations of the βA globin chains and modulated by polymorphisms. These are important disorders in medical history, as they became prevalent globally in regions where P. falciparum malaria was endemic. Heterozygous or carrier states conferred a survival advantage; however, doubly heterozygous or homozygous states cause severe hemolytic anemia and multi-organ complications. These disorders are somewhat unique in that all humans have alternate genes for fetal globin chains, which are expressed in fetal life but are silenced on a developmental clock in infancy. An established approach to ameliorating conditions of abnormal adult globin genes is to reactivate, or increase expression, of the endogenous fetal globin genes to replace the missing protein chains in beta thalassemias or inhibit polymerization of hemoglobin S and reduce the red cell abnormalities. This review provides a high-level overview of cell and molecular mechanisms that mediate fetal to adult globin gene switching and pharmacologic therapies that can reactivate fetal globin through different actions. Intermittent or metronomic dosing regimens have overcome challenges of undesirable off-target effects by agents that cause erythroid cell growth arrest. Multiple pharmacologic candidates reactivate or increase the expression of fetal globin protein and proportions of red blood cells containing HbF (F-cells). Hydroxyurea maintains high levels of HbF if begun in infancy, with some decline in mid-childhood. It elicits lower responses in HbF in adult patients, but still has broad clinical benefit in reducing many complications. However, many adult patients do not tolerate optimal hydroxyurea dosing due to cytopenias. Parenterally administered therapies with differing molecular actions, such as demethylating agents and histone deacetylase inhibitors, have shown proof-of-principle in reactivating HbF. Orally bioavailable candidates with complementary molecular mechanisms are in trials. Combining fetal globin-inducing agents with other therapies with complementary mechanisms, such as recombinant erythropoietin that promotes the survival of red blood cells and therapeutics that promote erythroid cell metabolism, should have additive effects. These pharmaceutical candidates offer great clinical potential and global feasibility for ameliorating these serious diseases.

Differential expression of adhesion molecules in sickle cell anemia and gut microbiome effect

Sickle cell anemia (SCA) causes a long-standing vascular inflammation state, leading to endothelial dysfunction and chronic overexpression of several adhesion molecules, which contributes to acute and constant vaso-occlusive (VOC) episodes. It has been demonstrated that hydroxyurea (HU) can reduce VOC events, organ damage, blood transfusions, and even the adhesion properties to endothelial cells of SCA subjects. Due to VOC episodes, these patients are also more susceptible to recurrent bacterial translocation and dysbiosis. Given this, our study aimed to uncover the interplay between adhesion molecules, gut microbiome, and hydroxyurea in a population of Angolan SCA children. Serum and fecal samples were obtained before and after HU treatment in 35 children. After HU, four of these adhesion molecules were significantly reduced: sE-selectin (p = 0.002), ADAMTS13 (p = 0.023), sICAM-1 (p = 0.003), and sVCAM-1 (p = 0.018). A positive correlation was observed between the number of neutrophils and sICAM-1, platelets, and sP-selectin, and also between leukocytes, sICAM-1, and sVCAM-1. Most taxa showing a significant correlation mainly belonged to the Clostridiales order. Specifically, from the Clostridium genera, the groups g19, g21, and g34 were all negatively correlated with HbF levels; g19, g21, and g24 positively correlated with leukocytes; g19 positively with neutrophils and sVCAM-1; and g34 positively with E- and P-selectin. Serratia, an opportunistic pathogen, was positively correlated with sE-selectin and sICAM-1 levels. Additionally, a negative correlation was observed between sP-selectin and Bifidobacterium. Research studies in this area could improve our understanding and contribute to finding new prognostic biomarkers to guarantee precise SCA patient stratification and predict severe complications.

Exploring The Effect of Wheat Grass Juice on Thalassaemia: A Comprehensive Review

Thalassemia is a hereditary blood disorder characterized by a deficiency in the oxygen-carrying protein (haemoglobin) and a reduced number of red blood cells in the body compared to normal. Mild forms of thalassemia may not necessitate treatment, while severe cases may require blood transfusions or a stem-cell transplant from a donor. Wheatgrass extract is seen as a supplementary treatment option for thalassemia, although research in this field is still in its early stages. Wheatgrass is a low-calorie substance but rich in essential nutrients, including antioxidants like glutathione, vitamin C, and vitamin E that plays a crucial role in combating harmful free radicals in the body, reducing oxidative stress, and providing protection against conditions such as arthritis, cancer, and neurodegenerative diseases. The proposed mechanism behind wheatgrass extract involves the swift absorption of chlorophyll and its action at the cellular level in the bone marrow, facilitating heme production. Treatment with wheatgrass tablets has been found to maintain serum ferritin levels and increase HbF levels in children with thalassemia who undergo frequent blood transfusions. However, it does not appear to reduce the frequency of blood transfusions required. Wheatgrass tablets also contribute to an improved quality of life for children with thalassemia. The present study aims to investigate the effectiveness of wheatgrass therapy in patients with transfusion-dependent anemia, further extensive studies involving a larger patient population would be necessary.

Two cases of vitamin B12 deficiency in patients with beta-thalassemia trait: lessons in diagnosis

BackgroundCoexisting pathologies is not a new phenomenon and can cause diagnostic difficulties when they overshadow one another. They may alter the cytomorphology of cells and the machine readings to an extent that the actual diagnosis is missed. One such scenario is created by coexisting megaloblastic anemia and beta-thalassemia trait where the RBC indices and the hemoglobin chromatogram findings conform to neither of the two. Case presentationWe present two cases of anemia presenting with normocytic normochromic indices, increased red cell distribution width (RDW), elevated HbA2 levels and moderately high HbF levels in both of them and an additional low HbA1c in case 2. Upon evaluation of peripheral smear and biochemical tests, a non-immune hemolytic component was also identified with deficient Vit B12 levels in case 1 and highly elevated levels post-supplementation in case 2. ConclusionsTaking together the peripheral smear, erythrogram, chromatogram and biochemical findings, it was deduced that the alterations were caused by coexisting beta-thalassemia trait and megaloblastic anemia. Vit B12 deficiency was the cause behind hemolysis owing to intramedullary destruction of abnormal precursors. Upon supplementation in case 2, the immediate reticulocyte response was the reason behind spuriously low HbA1c.

Sex-Related Differences in Fetal Hemoglobin Levels in Sickle Cell Patients

Sickle cell disease (SCD) continues to be the most common inherited blood disorder in the United States, characterized by a mutated HBB gene in hemoglobin subunit β (Kato 2018; Sedrak 2023). Currently, hydroxyurea is the gold standard treatment for SCD due to its mechanism of raising fetal hemoglobin (HbF) levels, ultimately lessening pain crises and need for blood transfusions (Acharya 2023). Prior to widespread usage of hydroxyurea, significant differences were found regarding HbF levels between males and females. In many cases, females were found to have, on average, higher HbF levels (El-Hazmi 1994; Ceglie 2019; Solovieff 2010; Sutnick 1968). The aim of this study is to determine whether sex-related differences presently exist in HbF levels in patients with SCD after Hydroxyurea use. This is a cross-sectional study conducted at the Center for Blood Disorders in Augusta, Georgia, consisting of a total of 496 patients diagnosed with SCD. Variables analyzed from this database included sex (male v. female), levels of HbF, and common complications of SCD: pulmonary hypertension, retinopathy, avascular necrosis, and thrombosis. Levels of HbF were calculated based on percentage and averaged. Two-sided t-test was used to identify differences between male and female HbF levels. Correlation of common complications of SCD with sex was observed using Pearson's coefficient and Fisher's z-test using R version 4.2.3. P value &amp;lt;0.05 was taken as significant. To control for confounding factors, HbF levels and age were included as covariates in the logistic regression when exploring the relationship between sex and complications of SCD. The 496 SCD patients consist of 233 males and 263 females. The males had a mean HbF of 8.71 (SD 9.84), and the females had a mean HbF of 9.83 (SD 10.4). A two-sided t-test resulted in a p-value of 0.21. 85 patients (45 female) had a history of pulmonary hypertension. The correlation between female sex on likelihood of developing pulmonary hypertension controlling for age and HbF was -0.24 (SE 0.22).121 patients (66 female) had a history of retinopathy. The correlation between female sex and the likelihood of developing pulmonary hypertension controlling for age and HbF retinopathy was -0.0066 (SE 0.21).177 patients (86 female) had a history of avascular necrosis. The correlation between female sex and likelihood of AVN controlling for age and HbF was -0.43 (SE 0.19).131 patients (72 female) had a prior thrombotic event. The correlation between female sex and likelihood of thrombotic event controlling for age and HbF was -0.12 (SE 0.19). The findings reveal no significant relationship between sex and HbF levels. We posit that this may likely be due to the effect of hydroxyurea treatment for SCD, as prior to treatment, there were significantly higher HbF levels in females (El-Hazmi 1994; Ceglie 2019; Solovieff 2010; Sutnick 1968). Adjusting for age and HbF levels, we found that there were no significant differences between the sexes in terms of risk for developing complications of pulmonary hypertension, sickle cell retinopathy, and thrombotic events. We did find that there was a significant difference between the sexes in terms of risk for developing avascular necrosis, where females were shown to have a decreased risk compared to males. Due to our limitation with sample size, next steps would entail analyzing these relationships with a larger database. With a more extensive data set of patients with SCD, further relationships may be elucidated regarding sex differences in the progression of disease that could aid in informed treatment decisions.

Methylation Patterns of Fetal Hemoglobin Regulating Genes in High-Risk (HR) -MDS Patients Following Treatment with Azacytidine

Background: Current standard of care for HR-MDS patients, i.e. hypomethylating agent (HMAs) treatment with azacytidine (AZA) or decitabine (DAC), is associated with a 30-50% response rate, and many efforts have been made to identify predictive factors for response. Fetal hemoglobin (HbF) levels have been proposed as a prognostic index for DAC treatment (Stomper J. et al, 2019), but no study has examined its prognostic value in AZA treated patients, and the mechanism of γ-globin chain re-expression has not been investigated. Methods: Bone marrow (BM) aspirates of 28 HR-MDS or CMML patients were collected at baseline and at the first evaluation of response, following 6 cycles of AZA treatment. Methylation of Cytosine followed by Guanosine (CpG) sites of the γ-globin gene promoter and CpG 326 of ZBTB7A/LRF, a previously characterized epigenetic repressor of HbF (Chondrou V. et al, 2022), were detected with pyrosequencing analysis in total genomic DNA, extracted from BM samples, pre- and post-treatment. Response to AZA was characterized as marrow response (mCR), when blasts were &amp;lt;5% and were reduced &amp;gt;50% from baseline, and as hematological response (HI-R) when there was at least one lineage improvement. HbF was measured with HPLC from the peripheral blood of 20 patients, at 5 time-points (before 0, 1, 2, 4 and 6-7 cycles of treatment), to test its expression pattern and potential prognostic significance. HbF values &amp;gt;1% were considered induced, as in previous studies (Stomper J. et al, 2019). For statistical analysis IBM SPSS 28.0.0.0 program was used. One patient with extremely high HbF before treatment (HbF 0=13.4%) was excluded from the analysis, as well as the CpG site 3 of γ-globin gene promoter, which was 100% methylated pre- and post- AZA treatment. Results: Median baseline HbF levels were 0.6% (range 0 - 2.6), and they were increased to 0.8% (range 0 - 1.8) and to 1.1% (range 0 - 3.5), at 2 and 6 months, post-AZA treatment, respectively. Difference in the repeated measurements of HbF was of borderline statistical significance (p=0.068), specified between cycles 2 and 6 (p=0.038). Correlation analysis showed a significant association of mCR with induced HbF after 6 cycles of treatment (p=0.011, r s=0.618) and a strong positive correlation between elevation of HbF at cycle 2 and time to leukemia progression (p=0.019, r s=0.886). Overall, median methylation of the γ-globin gene promoter was 73.4% and 72.8% pre- and post-AZA treatment, respectively (p=0.159). However, patients exhibiting any kind of response showed reduced methylation at site 2 post- AZA, at the limit of statistical significance (p=0.095 for mCR patients and p=0.066 for HI-R), whereas site 4 was significantly hypermethylated among HI-R patients (p=0.042). A negative correlation between methylation of the γ-globin gene promoter and gene expression was also identified (p=0.008, r s=-0.427), particularly at the sites 2 and 5 (p 2=0.011, p 5=0.004). Methylation analysis of CpG 326 of ZBTB7A/LRF showed significant hypermethylation at site 1 (p=0.044) and reduction of methylation at site 22 (p=0.043), following AZA treatment. When analysis was restricted among responders only, there was significant hypermethylation at site 1 (p 1=0.020) and borderline significant hypermethylation at sites 5 and 11, among mCR patients (p 5=0.069, p 11=0.079). Conversely, sites 9 and 13 were significantly hypermethylated among non-responders (p 9=0.034, p 13=0.047). With Spearman's analysis, a significant negative correlation between methylation fold change in site 13 and mCR was observed (p=0.002, r s=-0.555). Although no correlation between HbF and CpG 326 methylation status pre- treatment was observed, after 6 cycles of AZA a borderline correlation was identified between HbF levels and fold change of mean methylation of CpG 326 (p=0.05, r s=0.482). Moreover, induced HbF levels were related at the limit of statistical significance to increase in methylation at sites 1,3,5,11 and 22 (p 1=0.077, p 3=0.052, p 5=0.087, p 11=0.061, p 22=0.060). Conclusions: In this study, a relationship of γ-globin gene promoter methylation status and HbF levels was found among HR-MDS patients, treated with AZA. Moreover, hypermethylation in CpG326 of ZBTB7A/LRF after AZA treatment was associated with HbF levels, and different methylation patterns were observed between responders and non-responders. Further research is needed to clarify the role of LRF in MDS response to AZA.

Is Epigenetic Modulation to Induce Fetal Hemoglobin Translatable in Sickle Cell Mice?

Sickle cell disease (SCD) is a genetic disorder caused by a mutation in the β-globin subunit of hemoglobin, resulting in the formation of HbS. Under deoxygenation, HbS polymerizes leading to red blood cell sickling, increased hemolysis and multi-organ damage. During human fetal development, due to expression of the γ-globin gene, the predominant type of hemoglobin produced is fetal hemoglobin (HbF). However, after birth, this shifts to adult globin (HbA or HbS in SCD). This is driven by epigenetic repression of γ-globin due to an increased methylation of its gene promoters. DNA methyltransferase 1 (DNMT1) is an important enzyme for DNA methylation and is known to be pivotal in regulation of HbF expression. Reactivation of HbF provides a functional hemoglobin, and therefore has the potential to treat SCD symptoms ( Steinberg et al. JAMA 2003;289:1645-51). HbF induction is an accepted treatment strategy in SCD; even small increases result in decreased vaso-occlusive crises and mortality ( Kato et al. Nat Rev Dis Primers 2018;4:18010). Decitabine inhibits DNMT1 activity, thus promoting γ-globin expression and thereby increasing HbF levels. While inhibition of DNA methylation is known to cause HbF induction in humans and non-human primates, the effects observed in SCD mouse models are more ambiguous. This study investigated to which extent decitabine treatment could induce HbF expression in the Townes SCD model. In Townes mice, the murine globin genes have been substituted for their sickle human counterparts, HBA, HBB sickle and HBG1, and mimic many features of human SCD. Mice aged 4-5 weeks were dosed subcutaneously 3 times a week for 12 weeks with research-grade decitabine (0.6 mg/kg or 0.4 mg/kg) or vehicle. Blood samples were collected for analysis of HbF protein levels by HPLC (represented as % of total Hb) and F-cells by flow cytometry (represented as % of the total RBC population positive for HbF), complete blood counts, histology, and other markers of disease and organ damage. Results are presented as mean ± SD. Groups were compared using an ANCOVA model, adjusting for multiple comparisons (Dunnett) with p&amp;lt;0.05 considered statistically significant. For both treatment groups, HbF was significantly elevated compared to the control group, with the maximal response observed at 12 weeks (Figure 1). F-cells at the end of the study were increased in both 0.4 mg/kg (11.4±1.5%) and 0.6 mg/kg (11.8±1.4%) groups compared to vehicle (4.5±0.6%). The same was observed for protein levels: 0.4 mg/kg group (1.2±0.3%), 0.6 mg/kg (1.4±0.3%) compared to vehicle (0.4±0.1%). Interestingly, after 12 weeks RBC and reticulocyte counts were significantly decreased in treatment groups and mean corpuscular volume (MCV) was significantly increased. No changes on LDH, bilirubin and liver markers (ALP, ALT, AST) were observed at 6 or 12 weeks. The results showed that treatment groups had significantly higher HbF levels than the vehicle group. However, the level of induction was lower than observed for inhibition of DNA methylation in humans and primates. The decrease in RBCs and reticulocytes could be partially explained by a combination of HbF induction, reduction of sickle RBC, and inhibition of erythropoiesis. The lack of changes in disease markers suggests that the increase in HbF levels in Townes mice might not be sufficient to alleviate the disease. This observation is consistent with recently published data (Woodard et al. Dis Model Mech. 2022;15(6)) that indicates that Townes mice are less suitable for studying this mechanism of action since, even though they have all human globin genes and some proximal regulatory elements, they lack key cis-acting distant DNA elements that regulate the globin genes. However, in primates the globin structure and regulation mechanisms are similar to human (Hardison. Cold Spring Harb Perspect Med. 2012;2(12)). In conclusion, although the measured levels of HbF protein were no higher than 2%, we found that decitabine can induce HbF expression in the Townes mouse model of SCD. However, within the 12-weeks, there was no clear beneficial effect on the disease markers studied. The successful induction of HbF suggests that better outcomes might be achieved with further optimization of the dosing and duration of the study. This indicates that SCD mice may be useful for preclinical studies of HbF induction, but caution is needed when extrapolating results to humans.

Avascular Necrosis of Femur (AVNF) in Patients with Sickle Cell Disease: A Systematic Study from India

Introduction: Sickle cell disease (SCD) is one of the most common monogenic disorder world-wide and is a major health burden in India. Limited information is available on the prevalence of avascular necrosis (AVN) in Indian sickle cell patients. The present study focuses on understanding the prevalence of AVN of hip in patients with SCD and its correlation with different biochemical parameters and associated genetic modifiers. Methodology: SCD individuals at steady state with no blood transfusion prior to 3 months were recruited in the study after informed consent by a consecutive sampling for the study at ICMR-Centre for Research Management and Control of Haemoglobinopathies (ICMR-CRMCH), Chandrapur. All the clinical details including history and examination findings were noted. Laboratory evaluation included complete blood count, HPLC analysis, liver function test (LFT) and renal function tests and genetic modifiers including alpha-gene deletion and XMN polymorphisms. MRI and X-ray of both hip joints was performed for diagnosis of AVN. Results: One hundred SCD individuals (44 males: 56 females) were enrolled in the study. The median age of individuals was 18 years (IQR: 13-29 years). Individuals were categorized into three groups based on their ages. Children group (6-12 years): 23years, adolescents group (13-17 years): 23 individuals, and Adults (18-52 years): 54 individuals. Sixty five individuals were on drug hydroxyurea (HU), while remaining 35 were not taking HU. The median dosage of HU was found to be 11.9 mg/kg/day (IQR: 9.17-13.5 mg/kg/day). The current study reports the spectrum of avascular necrosis of femur (AVNF) involving normal, early organ dysfunction to end organ damage as 43/96 (44.8%) FICAT stage 0, 40/96 (41.7%) AVNF stage I/II and 13/96 (13.5%) AVNF III/IV/Total hip anthroplasty (THA). The median age (interquartile range) of Ficat Stage 0, I-II and III-IV was found to be 13 (9-17) years, 24.5 (17.3-31.8) years and 23 (18-34) years respectively. Modified harris hip score for Ficat Stage 0, I-II and III-IV was found to be 84 (68-91), 72 (55.0-86.0) and 70 (38.0-89.5) respectively. The mean ± standard deviation (S.D.) levels of hemoglobin (Hb) and HbF% were 9.7±1.6 gm/dl and 21.2±6.6% respectively. SCD individuals who were on drug HU therapy showed higher levels of Hb and HbF% levels, compared to those without HU therapy (p=0.03). Levels of Hb and hematocrit were positively associated with AVNF progression. HbF levels showed no association with AVNF stages. Levels of alkaline phosphatase (ALP) showed negative association with AVNF stages. Genetic modifiers such as α-thalassemia and Xmn1 polymorphism showed no association with present status of AVNF. Conclusion AVNF is frequent complication of SCD leading to significant morbidity especially in young adults. AVNF was more frequent with higher haematocrit, but did not show correlation with HbF levels, α- gene deletion, XMN polymorphism and HU therapy. More research needs to be focused on prevention of AVN.

Neighborhood Disadvantage Increases Risk of Adverse Clinical Events in Children with Sickle Cell Disease

Background: Hydroxyurea is the most widely used pharmacologic agent to treat patients with sickle cell disease (SCD). Hydroxyurea treatment has well established effects of inducing expression of fetal hemoglobin (HbF) and a beneficial impact on clinical outcomes such as reduced number of vaso-occlusive (VOC) events, transfusions, and hospitalizations. In non-SCD populations, living in socio-economic disadvantage is a well-established factor for poor health outcomes. However, there is a paucity of data to describe how social stressors impact children with SCD. We hypothesized that socio-economic disadvantage impacts risk of adverse clinical outcomes in pediatric SCD patients even while on hydroxyurea therapy. Methods: We performed a retrospective chart review on 121 pediatric patients with severe SCD genotypes (homozygous HbS and sickle-beta 0 thalassemia) seen at Texas Children's Hospital (TCH) between 2010-2021. All patients were treated with hydroxyurea for a minimum of five years. Adherence to hydroxyurea was assessed through lab markers including absolute neutrophil count and reticulocyte counts. Patients not adherent were excluded from analysis. We examined the incidence of all clinical events for a total of 1026 patient years, including the number of office visits, ER visits, hospitalizations, transfusions, VOC, acute chest syndrome episodes (ACS), acute splenic sequestration (ASS), and febrile illness. We collected laboratory data including absolute neutrophil count, hemoglobin level, and HbF levels for each patient per year they were on hydroxyurea. We used the area deprivation index (ADI) to determine a score of neighborhood disadvantage amongst our cohort of patients. The ADI is a factor-based index which uses 17 US Census variables including poverty, education, and employment. We used individual residential addresses during our observation period to assign a geocode specific to each individual and obtain an ADI score. The ADI scores are ranked from 1-10, with higher ADI rankings reflecting a higher level of disadvantage. Results: All individuals with SCD had a robust response to hydroxyurea within their first year of initiating the drug (&amp;gt;20% HbF). We stratified our cohort based on their ADI scores into low ADI (1-3; n=42); medium ADI (4-6; n=42); and high ADI groups (7-10; n=37), where high ADI is the group with highest levels of disadvantage. All three groups had a similar average duration of hydroxyurea treatment. There were no significant differences in age, sex, or reason given for starting hydroxyurea between the ADI groups. When we examined hydroxyurea response, there was no significant difference in HbF levels at 1 year (23.8 vs. 24.06 %HbF in the low vs. high ADI groups) or after 5 years (19.6 vs. 18.6 % HbF in the low and high ADI groups). Individuals with high ADI did started hydroxyurea at a younger age (2.9 years vs. 4.9 years, p=0.02). We found that any individual living in an area with higher ADI had an increased incidence of adverse clinical events. We calculated the incidence of each clinical event per 100 patient years in our 3 ADI groups and used a conditional maximum likelihood estimate of rate ratio method to compare incidences (Table 1). We found that among individuals living in an area with a higher ADI (more deprived region), there was increased frequency of ER visits, hospitalizations, transfusions, VOC, and ASS. In particular, patients with the highest ADI had a 3 and 5 times higher rate of VOC and ASS, respectively (Table 1). Discussion: While we did not observe an association between ADI and HbF expression, our results show that higher neighborhood disadvantage is associated with poorer clinical outcomes among hydroxyurea-adherent pediatric patients with SCD who maintained a robust response to the drug (&amp;gt;20% HbF). All individuals in our study had a similar number of routine office visits at our clinic but any patient living in an area of high ADI had significantly more ER visits and hospitalizations for VOC and ASS events. While hydroxyurea is shown to reduce hospitalizations and VOC events in pediatric sickle cell patients, we show that neighborhood disadvantage can influence clinical outcomes even among patients who respond to hydroxyurea. More analysis remains in order to better characterize this association, and to understand additional strategies that can be used to reduce clinical events in pediatric patients of lower socioeconomic status.

Fetal Hemoglobin Decrease during Voxelotor Treatment

Sickle cell disease (SCD) is an inherited disorder caused by a point mutation in the β-globin gene leading to the formation of hemoglobin S (HbS). The polymerization of deoxygenated HbS is the first event in the molecular pathogenesis of SCD resulting in sickling of red blood cells (RBC), and hemolytic anemia which has been shown to be associated with organ damage and early death. Hemolytic anemia is defined by an accelerated rate of destruction RBC resulting in a lowered Hb level and a reduced gas transport capacity. Because Hb S in its oxy (R) conformation do not polymerize, drugs modifying hemoglobin (Hb) to increase the proportion of oxy-HbS have been propose to inhibit HbS polymerization. Voxelotor is such a molecule, which allosterically modifies Hb-oxygen affinity improving anemia and reducing hemolysis. However, the impact of Voxelotor on HbF levels is unknown. We describe here variations of %HbF and Mean corpuscular HbF (MCHbF) in a cohort of homozygous SCD patients treated with Voxelotor in our Sickle Cell Referral center. We conducted a prospective register study to analyze clinical and biological evolution of SCD patients treated with Voxelotor at 1500mg taken orally once daily. From December 2021 through December 2022, 25 SCD adult patients were followed during a median of 7 months [1-12]. Among them, HbF values were analyzable for 15 patients (SS gentype n=14; women in 73%; median age of 50 years [24-61]) who completed 6 months of Voxelotor with no transfusion during the same period; and with a stable dose of hydroxyurea (HU), for at least 3 months before inclusion and during the study in case of patients treated by HU (n=10). The dose of Voxelotor was stable for 13/15 patients and was decreased in 2 patients due to skin allergy (n=1) and moderate digestive intolerance. One patient died after 6 months of treatment in a context of end-stage renal failure and severe pulmonary hypertension not related to Voxelotor treatment. Mean corpuscular HbF (MCHbF) was calculated (MCHbF (pg) = MCH x %HbF). HbF percentage was measured by high performance liquid chromatography (Biorad, Variant II, beta-thal dual program). All participants provided written informed consent (CPP Erythropedie). From baseline to 6 months of follow up mean Hb (g/dL) concentration increased from 7.4 [5.4-8.5] to 8 [5-11.9] (p=0,0003; Figure A); absolute reticulocyte count (ARC ; Giga/L) decreased from 158 to 145 (p=0,005), %HbF decreased by 63% in all patients from 7,1% to 3,3% (p=0,008; Figure B) and MCHbF (pg) decreased from 3,36 to 1,03 (p=0,001; Figure D). A decrease in % HbF was observed from the first 15 days of treatment in both groups of patients treated or not with HU (Figure C) ; no changes in mean corpuscular volume (p=0.15) was observed in patients treated with HU during follow up. The HbF decrease in SCD patients treated with Voxelotor could be explained by different mechanisms: - Reduction of stress erythropoiesis which is due to an increase in erythroid output in response to anemic stress associated with a reduced expression of BCL11A, a transcriptional repressor that inhibits adult-stage HbF expression. This hypothesis is supported by the reduction in reticulocytes in patients treated with Voxelotor - The loss of an HbF-related survival advantage for SCD RBCs, while the normal RBC lifespan is approximatively 120 days, in SCD RBCs it is only a sixth of it. HbF is a major modulator of SCD and prolonge SCD RBCs survival. Its protective effect relies on its quantity and distribution among the RBC population, which is often heterogeneous in SCD patients. Protection against polymerisation of Voxelotor is probably more homogeneous among RBCs. As a result, RBCs containing low levels of HbF, which would normally disappear, have a prolonged lifespan. Similarly, it was presumed that sickling of erythroblasts could lead to ineffective terminal erythroid differentiation with an anti-apoptotic role for HbF during the terminal stages of erythroid differentiation. However we found no significant difference for index of ineffective erythropoiesis (soluble transferrin receptor / absolute reticulocyte count) before and after 6 months of treatment. The question raised is therefore that of the risk of a rebound effect upon discontinuation of Voxelotor, which has a short half-life, during the time it takes for HbF to increase. To better study this hypothesis, distribution of HbF/RBC will be studied in the HEMOPROVE trial (NCT05199766) currently in progress.

NR2F1 : A Novel Candidate for Gamma Globin Activation

The reactivation of human gamma globin holds tremendous promise as a potential treatment for hemoglobinopathies, including sickle cell disease and beta-thalassemia. Despite identifying various repressors of fetal globin genes in adult erythroid cells over the past decade, evidence concerning stage-specific factors that activate human fetal globin prior to the switch to adult beta-globin remains inadequately understood. In our study, we constructed an erythroid-specific gene regulatory network (GCN) by integrating multiple RNA-seq datasets from erythroid cells at different stages of differentiation and development. Our analysis unveiled both known HbF activators, like HIC2, and novel candidates. Among the novel contenders, NR2F1, a member of the steroid/thyroid hormone receptor superfamily, emerged as a prominent candidate. To validate our predictions, we overexpressed NR2F1 in Hudep2 cells and observed more than a four-fold increase (28% vs. 6%) in the proportion of F cells and a three-fold rise in HbF levels as measured by HPLC. In addition, the overexpression of NR2F1 did not appear to impact beta-globin expression or cell differentiation. Intriguingly, we observed a significant reduction in the protein level of BCL11A, a master regulator of HbF, despite no major change in the total RNA level of BCL11A. This observation suggests that NR2F1 plays a role in the post-transcriptional modification of BCL11A. Additionally, NR2F1 overexpression led to an upregulation of Lin28B expression in Hudep2 cells. Lin28B is known to directly bind BCL11A mRNA and prevent its effective translation without disturbing BCL11A transcription. Consequently, the observed upregulation of Lin28B in NR2F1-overexpressing cells implies a potential NR2F1-Lin28B-BCL11A axis involved in controlling human hemoglobin switching. In conclusion, our findings propose NR2F1 as a novel activator of gamma globin, representing an attractive target for gamma globin reactivation. Additional investigation is required to explore the molecular mechanisms through which NR2F1 regulates gamma globin expression and its role in the NR2F1-Lin28B-BCL11A axis.

Comparative Analysis of Hematological Parameters in Indian Sickle Cell Anemia Patients Treated with Low Dose (10mg/kg/day) Versus Standard Dose (20mg/kg/day) Hydroxyurea

Introduction: Sickle cell anemia (SCA) is a hereditary genetic disorder characterized by the production of abnormal hemoglobin (HbS), which leads to altered physiological properties. Hydroxyurea (HU) is an established oral drug that has demonstrated the ability to ameliorate the severity of the disease mainly by increasing the production of fetal hemoglobin (HbF), thereby reducing sickle cell crises. Studies in the Indian population have shown positive clinical outcomes with a low dose (10 mg/kg/day) of hydroxyurea. Low dose is recommended by most of the physicians in India due to fear of adverse events and noncompliance of patients for regular monitoring of blood parameters. However, the effectiveness of low-dose HU compared to the standard dose (20 mg/kg/day) in reducing sickle cell anemia crises remains uncertain due to the diverse clinical severity of SCD in the Indian population. To address this question, the study aimed to conduct a national level randomized control trial involving SCA patients from various ethnic backgrounds to definitively establish the benefits of low-dose HU for Indian patients compared to the standard dose. Materials and Methods: Till date the study enrolled 140 sickle cell anemia patients (2-14 years) after informed consent. Patients were randomly assigned to either low (ARM 1: 10 mg/kg/day) or standard (ARM 2: 20 mg/kg/day) doses of hydroxyurea. 37 patients had been followed up for 6 months' time point of hydroxyurea therapy. Three ml of whole blood samples were collected in K2-EDTA tube, anthropometric details and clinical parameters of patients were studied. Results: 18 participants were allotted ARM 1 with a mean age of 8.9 ± 2.8 years and 19 were allotted ARM 2 with a mean age of 8.6 ± 2.5 years. All patients were followed upto 6 months after hydroxyurea treatment. The clinical severity was classified as class 1 and class II based on the clinical events of patients. It was found that 26 patients are classified under the class I category of severity while 10 patients classified under the class II category of severity. 6(60%) participants with baseline HbF level below 15% had Class II severity whereas 3(11.5%) participants with baseline HbF level of more than 15% had Class II severity. The effect of hydroxyurea dose on haematological indices was also studied which revealed that there was significant decrease in WBC, platelet count by 2.18 ± 2.24 10 3/µl, 24 ± 136.6 10 3/µl in ARM 1 compared to ARM II 4.08 ± 2.6 10 3/µl, 50 ± 127.39 10 3/µl. A rise in hemoglobin level by 0.18 ± 0.71 gm/dl in ARM I, 0.71 ± 0.77 gm/dl in ARM II and MCV by 3.29 ± 2.61 fl in ARM1, 5.28 ± 3.57 fl in ARM II. The difference was found statistically significant in both the ARMS. (P&amp;lt;0.001). The RBC count in patients did not show a significant elevation in both the ARMS. The absolute neutrophil count in patients were significantly reduced in ARM II by 2874 ± 1748 per µl compared to 1963 ± 1748 per µl in ARM I. Two patients in ARM II showed a reduced ANC level below 1000 thus, hydroxyurea therapy among those two patients was stopped and resumed after a week. Interestingly the rise in HbF was significantly higher in ARM II by 4.81 ± 2.71 % compared to 1.55 ± 2.32 % in ARM I. The critical clinical events such as VOC, Stroke, ACS was not observed in patients at baseline and after 6 months of HU follow up. Conclusion: The study demonstrated that hydroxyurea treatment in sickle cell anemia patients led to a significant increase in HbF levels in ARM II compared to ARM I. Haematological parameters like WBC Count, platelets, ANC was significantly lower in ARM II with 2(10.5%) of patients in ARM II having ANC below 1000 warranting close monitoring during treatment. Furthermore, the absence of critical clinical events during the 6-month follow-up period suggests the potential benefits of hydroxyurea therapy in managing sickle cell anemia in both ARMS with a long term follow up providing more accurate results to arrive at conclusion.

Habit Efficacy Trial: A Multi-Site Randomized Controlled Trial of Community Health Worker Support to Increase Hydroxyurea Adherence of Youth with Sickle Cell Disease

Introduction: Despite disease-modifying effects of hydroxyurea (HU) on sickle cell disease (SCD), poor adherence among affected youth commonly impedes treatment impact. The HABIT multi-site randomized controlled efficacy trial aimed to increase HU adherence. Methods: Youth with SCD ages 10-18 years with impaired adherence were identified through laboratory evidence, primarily flagging levels of treatment-induced fetal hemoglobin (HbF). Eligible youth were enrolled as dyads with their primary caregivers for one year. We tested a 6-month phase of semi-structured supportive, multi-dimensional dyad intervention led by community health workers (CHW) with 4-5 visits addressing information, social issues/referrals, barriers, habit formation using goal-setting and cues, augmented by daily tailored automated text message reminders, compared to standard care. This phase was followed by a 6-month sustainability phase (months 7-12) of observation and, for the intervention group, 1 CHW booster visit. Primary intervention outcomes were 1) HbF levels compared to enrollment; and 2) proportion of days covered (PDC) for HU versus the pre-trial year. The secondary outcome was sustainability of these changes up to month 12. Results: Starting in 2020, the COVID-19 pandemic disrupted enrollment and clinic-based procedures. The trial enrolled 50 dyads, missing target enrollment. Compared to enrollment levels, both HbF level and PDC significantly improved within the intervention group at month 6 (p=. 03 and . 01, respectfully), with parallel increased MCV (p=.05). Increased HbF did not reach signifance compared to controls (p=.07). No significant within- or between-group differences were found at month 12. Conclusions: Within-group results suggest that our CHW-based dyad intervention with text message reminders improved HU adherence at 6 months but there were no between-group differences. Effects did not endure through the subsequent 6-month sustainability phase. These findings suggest that improved HU adherence for youth with SCD though our community-based, multi-modal support for youth-caregiver dyads temporarily improved usage. Durability of impact on adherence may require integrating CHW-led support and text reminders into clinical care.