Hb Profile Research Articles

Pharmacologic Inhibition of XPO1 By Selinexor Improves Late-Stage Erythropoiesis in Severely Affected β 0-Thalassemia/Hemoglobin E

Ineffective erythropoiesis due to accumulation of excess α-globin chains profounds unwarranted consequences in β-thalassemia. In severe β-thalassemia, the excess α-globin chains trap HSP70-the guardian of GATA1-within the cytoplasm. Thus, in the nucleus, GATA1 is degraded and leads to late-stage erythropoiesis arrest. XPO1 is a nuclear exporter that exports HSP70 from the nucleus to the cytoplasm. Previous study showed that chemical downregulation of XPO1 in β-thalassemia major using an old generation of XPO1 inhibitor (KPT-251) could improve late-stage in vitro erythropoiesis. Moreover, XPO1 inhibitor treatments in clinical trials revealed improvement of transfusion burden and hemoglobin levels in some patients with myelofibrosis. Together suggested that inhibition of XPO1 might be considered as a possible option for β-thalassemia treatment. Here, we investigated the effects of pharmacological XPO1 inhibition using old and new generation of XPO1 inhibitors, and natural products in human CD34 + hematopoietic stem and progenitor cells (HSPCs) derived from β 0-thalassemia/HbE with severe phenotypes. Coinheritance of common α-thalassemia were ruled out in all patients and severity score was computed using Sripichai scoring system (Sripichai et al. Am J Hematol 2008). HSPCs were purified from peripheral blood and subjected to 3-phase erythroid culture system. Nine compounds with known XPO1 inhibitory effect including five synthetic (KPT-185, KPT-276, KPT-330 or selinexor, KPT-335 or verdinexor and KPT-8602 or eltanexor) and four natural active compounds (curcumin, oridonin, piperlongumine and plumbagin) were evaluated in patient-derived HSPCs (n=1) for their potency and efficacy. Of these, selinexor exhibited the maximal efficacy in which the accumulation of CD71 Low/GPA High cell population was predominate. To affirm this finding, HSPCs derived from six independent β 0-thalassemia/HbE patients were treated with selinexor (5 and 10 nM) at early-stage of the in vitro erythropoiesis and maintained throughout the culture system. After treatments (n=3), XPO1 was downregulated in both cytoplasmic (5 nM; 1.5±0.1-fold, p < 0.005 and 10 nM; 1.7±0.5-fold, p < 0.05) and nuclear compartments (5 nM; 1.1±0.3-fold and 10 nM; 1.3±0.2-fold, p < 0.05). No significant cytotoxic effects were observed. In addition, effects of selinexor on erythroid differentiation and maturation were assessed by flow cytometry using CD71/GPA immunostaining and Wright-Giemsa staining. The results revealed that selinexor treatments could augment late-stage in vitro erythropoiesis (orthochromatic+enucleated/basophilic+polychromatic erythroid cell) in dose-dependent manner (5 nM; 1.4±0.4-fold and 10 nM; 3.5±1.8-fold, p < 0.05). This finding was correlated with erythroid cell morphology under a light microscope. We further explored whether XPO1 inhibition by selinexor (n=3) affects HSP70 and GATA1 expression. Homogenous erythroid cell population (CD71 High/GPA High) were collected and subjected for western blot analysis. We found that HSP70 was upregulated in the cytoplasm (5 nM; 1.8±1.0-fold and 10 nM; 2.1±1.1-fold). However, HSP70 and GATA1 in the nucleus were insignificant changed. Our finding demonstrated that manipulations of XPO1-HSP70 axis in the cytoplasm by selinexor were associated with accelerated late-stage erythropoiesis in severely affected β 0-thalassemia/HbE HSPCs. We then hypothesized whether selinexor functioned through an accumulation of HbF. Therefore, Hb profiles were investigated using HPLC. However, non-significant changes of Hb profiles and HbF levels were observed. With this finding, we purposed that selinexor functioned independently of HbF regulatory pathways and precise mechanisms underlying the regulation of late-erythropoiesis by selinexor are required. According to our preliminary data, an FDA approval compounds for multiple myeloma-selinexor-is a potent compound for improving in vitro late-stage erythropoiesis in HSPCs derived from severe β 0-thalassemia/HbE. Therefore, repurposing of selinexor to improve ineffective erythropoiesis in β-thalassemia is compelling. Moreover, combination treatments of selinexor with HbF inducers and/or SMAD2/3 blockers could be further validated to possibly achieve greater therapeutic benefits for β-thalassemia treatments.

The pivotal role of HbA1c assay to detect hemoglobinopathies: A 5-year observational retrospective study in the population of Southern France.

Mobility and migration flows are growing from different countries of the world to European countries, including France and in particular the Mediterranean basin. This study aimed to investigate the presence of hemoglobin (Hb) variants in outpatients/inpatients of the Montpellier Hospital (France) in whom an HbA1c assay had been performed and for which the country of birth had been informed. This is a retrospective study from January 2016 to December 2020 based on all high-performance liquid chromatography (HPLC) chromatograms (Tosoh Bioscience HLC-723G8) having an alarm of suspected Hb variant during HbA1c measurement. The corresponding samples were systematically sent to the hematology laboratory for confirmation and identification of Hb variant. Patient's medical history, clinical and demographic data were extracted from each medical chart. Statistical analyses were performed using XLSTAT® software, version 2016.06.35661. Three hundred sixty-three patients were confirmed with Hb variant exhibiting 17 different Hb profiles, highlighting the pivotal role of glycated hemoglobin (HbA1c) as a detection step. The prevalence of Hb variant in this southern French population was 0.71%, with the highest frequency for the beta-globin variants (n = 342/363; i.e., 94.2%), including the most common: S, C, E, and D in 200/342 (58.5%), 83/342 (24.3%), 29/342 (8.5%), and 11/342 (3.2%), respectively. Among patients with Hb variants, almost half (165/363; i.e., 45.4%) were born in the African continent with a predominance for Morocco (32/165; i.e., 19.3%) and Algeria (29/165; i.e., 17.5%). HbA1c assay is a useful tool to detect Hb variants. Hemoglobinopathies are a public health issue in the current French population which is a multiethnic society. Despite the monocentric nature of our study, we note a high frequency of Hb variants in the south of France, which underlines the importance of screening for Hb variants in the whole population.

Hemoglobin EE disease in young Laotian children: Hematologic features and the contributions of genetic variations to Hb F expression.

The wide variation in hemoglobin (Hb) F levels has been observed in patients with Hb EE disease. This study aimed to describe hematologic features and determine the effect of genetic variants on Hb F expression in young children with Hb EE disease. Hematologic features and Hb profiles of Laotian children aged 6-23 months, who originally enrolled in the Lao-Zinc study, were retrospectively reviewed. Only children with Hb EE disease, as indicated by DNA analysis, were included in this current analysis. Genetic variants, including the G γ-XmnI polymorphism (C>T) of the HBG2 gene, the HBS1L-MYB intergenic region on chromosome 6, and the BCL11A on chromosome 2 as well as the mutations occurring on the Krüppel-like factor 1 (KLF1) gene, were examined. In total, 205 children were diagnosed as having Hb EE disease with Hb F ranged from 1.2 to 43.7%. Most of the children had mild to moderate anemia with a remarkable microcytosis. Analysis of the genetic variants revealed an extremely high frequency of the G γ-XmnI (93.7%). Applying multiple regression analysis adjusted for age, sex, and α-thal gene, a positive relation was observed for the rs4671393 (coefficient=3.87, p= .005) and the rs2297339 (coefficient=2.48, p= .046), but not the G γ-XmnI. A statistically non-significant relation was noted for the rs9399137 and the -154 (C>T) KLF1 mutation. Our findings provide insight into complex situation of Hb F variability in young children with Hb EE disease; and this can guide to appropriate care and counseling to affected families.

Characterization of Hemoglobin Variants Due to in-Frame Deletions in the β-Globin Gene from CRISPR/Cas9 Gene Correction for Sickle Cell Disease

Introduction: Sickle cell disease (SCD) is caused by a single nucleotide mutation in the β-globin gene (HBB). CRISPR/Cas9 based gene correction approaches rely on inducing a double-strand break (DSB) at or near the sickle mutation, which subsequently results in gene correction via the homology-directed repair (HDR) or insertions/deletions (Indels) via non-homologous end joining (NHEJ). Frameshift Indels induce a premature stop codon and disrupt HBB production. Indels that preserve the reading frame may yield structurally abnormal β-globin chain with altered amino acid sequences and protein structures that can affect the globin chain stability, leading to thalassemia of uncertain pathogenic significance. The high rate and diversity of in-frame Indels as an unintended by-product of gene correction therapy confers a challenge for predicting therapeutic outcomes when it is not possible to frame the clinical behavior of hemoglobin (Hb) variants. Here we provided the molecular and structural characterization of the most commonly identified Hb variants due to CRISPR-induced in-frame deletions and proposed a putative pathogenic mechanism for the observed phenotype using human umbilical cord-derived erythroid progenitor cells (HUDEP2). Methods: HUDEP2 clonal cell lines carrying mutated Hb variants from in-frame deletions on HBB exon1 introduced by R-66S and R-02 CRISPR sgRNAs currently in use in preclinical and clinical studies for correcting sickle mutation, respectively, were established, and clonal genotypes validated by next-generation sequencing and droplet digital PCR based copy number assay. The Hb variants derived from R-66S include p.Val7_Ser10del (-12bp), p.Val7del (-3bp), p.Glut8del (-3bp), p.Glut8_Lys9del (-6bp), pVal7Thr13del (-21bp), p.His3_Lys9delinsGln (-18bp), and p.Thr5_Lys18del (-42bp), in the order of allelic abundance observed in the bulk population of edited cells. The Hb variants derived from R-02 include p.Val12_Ala14del (-9bp), p.Val12_Thr13del (-6bp), p.Ala14del (-3bp), p.Thr13_Gly17del (-15bp), and p.Thr13_Val19delinsMet (-18bp). Selected ten clonal cell lines carrying a unique combination of genotypes and the parent HUDEP2 were cultured for expansion in serum-free media for one week. All clones were subsequently subjected to erythroid differentiation media for ten days. Samples were collected on days 4, 7, and 10 of differentiation for analysis via high-performance liquid chromatography (HPLC) using an ionic column to access the Hb profile and spectrophotometry via a Hb assay kit to assess the total Hb quantity. Results: HPLC analysis demonstrated a significant qualitative variation in Hb profile in HUDEP2 clones carrying different Hb variants. p.Val7del is Hb Leiden, and the rest of Hb variants are not listed in the HbVar database. In clones carrying Hb Leiden in homozygous or heterozygous states, Hb Leiden eluted in the position of sickle Hb (HbS). A low percentage of multiple abnormal Hb X fractions was observed in all clones carrying Hb variants compared to parent HUDEP2, which hinted at the presence of unstable Hb variants or alpha precipitates. Levels of fetal Hb (HbF) increased in mutant clones, suggesting globin chain imbalance and hematopoietic stress. Clones missing multiple amino acids showed ineffective erythropoiesis and cell death by day 4 of differentiation, most likely exacerbated by the relative excess of the α-chains. Discussion: We found that unintended gene modifications can significantly impact Hb quality and quantity, reinforcing concerns about the safety of gene-editing therapy for SCD. In patients, cells carrying in-frame deletions in the β-globin chain could produce an unstable Hb and may contribute to a β-thalassemia-like phenotype. More work is required to further assess the consequences of the diverse Hb variants in combination with other unintended modifications that disrupt HBB in a bulk population of gene-edited cells. Detecting, profiling, and reducing these unintended modifications remains a priority to increase the efficacy and safety of gene-editing therapy for treating SCD or β-thalassemia. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Specific electrolyte effects on hemoglobin in denaturing medium investigated through electro spray ionization mass spectrometry

We examine Hofmeister specific ion effects of electrolytes added to protein solution under conditions minimizing electrostatic attraction between cations and positively charged protein. Hemoglobin (Hb) in aqueous solution at the denaturing pH = 2.7 is investigated in the presence of several metal chlorides, along with sodium and potassium bromides, iodides and thiocyanates, using electrospray ionization mass spectrometry (ESI-MS). Salt concentration was varied to maximize peak intensity and bell-shaped profile in the ESI-MS spectrum. The α-chain of myoglobin is identified as the main pattern of the ESI-MS spectra in all Hb-salt systems. Both peak intensity and quality of the bell-shaped profile of the protein spectrum decrease in the cation order: K+ > > Mg2+ > Li+ > > Na+ > Ca2+ ≈ Cs+ > Rb+ for Hb-Metal Chloride systems, and decrease in the anion order: Cl− > Br− > I− > SCN− for systems of both Hb-NaX and Hb-KX salts. To quantify salt addition effects two Hofmeister specific electrolyte parameters HS, and PS are proposed. HS is the mean (Hb-salt)/Hb peak intensity ratio, measured for the nine peaks used for ESI-MS spectra deconvolution, taken at the same m/z values of the Hb profile. PS is the ratio between HS standard deviation and HS, and provides a specific perturbation parameter measuring the loss of protein structure. These two Hofmeister parameters give clear evidence of the effects induced either by KCl, MgCl2 and LiCl that enhance protein peak intensity, or by NaBr, NaI, NaSCN and KSCN that induce the protein fragmentation, due to electrolyte-mediated dissociation.

Impact of one-rod levonorgestrel implant on the blood chemistry profile

The aim of this study was to investigate the effect of a one-rod levonorgestrel implant on the blood chemistry profile, including random blood glucose (RBG), haemoglobin (Hb), alanine transferase (ALT), aspartate transferase (AST), and the lipid profile, including total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides. This prospective cohort study was conducted at Raden Saleh Clinic, Jakarta, from 2010 to 2012. The implants were inserted subdermally in 30 patients. The subjects were evaluated every 6 month up to 2 years. Bivariate analysis using t-test or Wilcoxon signed rank test was performed for all variables. p < 0.05 was considered a significant value. The Hb, RBG, AST, and lipid profile levels were significantly different before and 6 months after one-rod implant insertion (p < 0.05). However, for 24 months, all of the parameters were still within normal limits and did not differ clinically. One-rod levonorgestrel implant insertion has a minimal effect on all blood chemistry profiles.

The effect of orthopedic screw profiles on the healing time of femoral neck fracture

One possible treatment for femoral neck fractures, especially in young people, is the use of bone screws or Lug screws. The design of these implants requires taking into account the biocompatibility of materials, mechanical properties plus surface properties, and thread’s geometric, as well as chemical properties, etc. Various profiles are designed for fracture fixation. The most famous of these profiles, which are introduced by the ISO standard, are HB, HC, and HD type profiles. This article investigates the performance of these profiles in reducing or increasing the healing time. This study is based on the rule of bone remodeling and using a set of three-dimensional computational (finite element) models. The study revealed that the HB profile outperformed the other two profiles. Meanwhile, HD profile was also better than HC profile.

Tunisian Newborn's Cord Blood: Reference Values of Complete Blood Count and Hemoglobin Fractions.

This study was aimed to establish local reference values for hematological indices and hemoglobin (Hb) fractions in umbilical cord blood (UCB) for the northern population of Tunisia. Our study included full-term newborns by vaginal deliveries. Hematological parameters were collected using an automated blood cell counter. The amounts of Hb fractions were measured by capillary electrophoresis of Hb. Statistical analysis was performed using R software. A total of 328 cord blood samples were analyzed. Among them, 154 (male: 44.8%, female: 55.2%) were used to establish reference values. The normal reference values of complete blood count (CBC) and Hb fractions were calculated. Mean neonatal Hb was 14.75 ± 2.26 g/dL. Gestational age affects the expression of CBC values as red blood cell (RBC), Hb, hematocrit (Hct), mean corpuscular volume (MCV), white blood cell (WBC), and the Hb profile. Umbilical blood hemogram parameters and Hb profile are affected by the environment; higher in newborns from urban regions but not affected by gender ratio. Reference ranges of normal CBC indices and Hb fractions have been successfully established in Tunisian neonates' UCB. Our data suggest reference values that could be useful for neonatal patients' laboratory results and clinical interpretation. · Reference values for CBC and hemoglobin fractions have been established.. · Hematological reference for UCB is useful to identify hemolytic anemia cases early.. · UCB hematological values are influenced by gestational age and probably by environmental factors..

β-Hemoglobinopathies in the Lao People's Democratic Republic: Molecular diagnostics and implication for a prevention and control program.

A high frequency of β-thalassemia in Lao People's Democratic Republic necessitates the importance of complete molecular data before a prevention and control program could be established. Limited data are available for Lao PDR. We have now reported an extended information on the molecular basis of β-hemoglobinopathies in this population. The study was done on 519 unrelated Laos subjects requested for thalassemia investigation. Hematological data were recorded. Hb profiles were obtained using a capillary electrophoresis system. α-And β-globin genotyping was performed using PCR and related techniques. Among the 519 subjects, 287 (55.3%) were found to carry β-hemoglobinopathies based on Hb and DNA analyses. These included Hb E carriers (n=135), homozygous Hb E (n=47), β-thalassemia carriers (n=70), Hb E-β-thalassemia (n=25), homozygous β-thalassemia (n=4), heterozygous δβ0 -thalassemia (n=2), and carriers of the β-Hb variant (n=3). Mutation analysis identified in addition to the Hb E, 8 different β-thalassemia mutations including codon 17 (A-T), codons 41/42 (-TTCT), NT-28 (A-G), codons 71/72 (+A), IVS1-1 (G-T), 3.4kb deletion, an initiation codon (T-G) and IVS2-654 (C-T). Two δβ0 -thalassemia carriers (12.6kb deletion) and three subjects with Hb Hope (β136GGT-GAT ) were identified. Hematological features associated with these β-hemoglobinopathies were presented. β-hemoglobinopathies in the Laos population is heterogeneous. This information is relevant for setting up a molecular diagnostics and can provide a basis for genetic counseling and enable prenatal diagnosis.

Red Cell Rheology Biomarkers to Assess Cure in Gene-Based Therapies

Introduction Red cell rheology is abnormal in sickle cell disease (SCD); red blood cells (RBC) are rigid, dense, and the sickle hemoglobin (HbS) polymerizes with deoxygenation. There are several devices commercially available and under development to assess RBC rheology. One is an oxygen gradient ektacytometer (Lorrca with Oxygenscan, RR Mechatronics) which measures RBC deformability under oxygenated conditions (EImax) and deoxygenated conditions (EImin), and the oxygen concentration at which deformability begins to worsen, point of sickling (PoS). A commercially available hematology analyzer, the ADVIA (Siemens), measures hemoglobin (Hb) by flow and colorimetric methods, permitting automated calculation of the percent dense red blood cells (%DRBC). Allogeneic hematopoietic stem cell transplant (alloHSCT) can provide a cure for SCD, and viable gene-based therapy options are under investigation to serve the many patients without a matched related donor. However, the level of HbS correction or functional Hb induction necessary to achieve a cure is still unknown. Clinical endpoints such as prevention of pain events are important, but it is possible to be pain free for several years while still experiencing organ damage. As gene-based therapy clinical trials move forward, we must assess the level of functional improvement beyond Hb profile and conventional clinical labs. We propose that the goal of any gene-based SCD therapy should be to normalize blood rheology to the level of an individual with sickle cell trait (HbAS), and that EImax, EImin, PoS, and %DRBC may be used to distinguish between HbAS and HbSS/Sβ0 genotypes. Methods Subjects: Blood samples were collected from 257 unique patients (17 HbAS, and 240 HbSS/Sβ0) under IRB-approved protocols at Texas Children's Hospital and University Medical Center Utrecht. Patients were 56% male, ages 9 months to 22 years. Some HbSS/Sβ0 subjects were on transfusion and hydroxyurea (HU) (Table 1). Fetal hemoglobin (HbF) levels ranged from 0-41%. Oxygen gradient ektacytometry: Blood collected in EDTA and standardized to a fixed RBC count was suspended in 5 mL polyvinylpyrrolidone at room temperature. 1.5 mL of the sample solution was injected into test cup. Each sample was run in duplicate. ADVIA: 250µL of blood collected in EDTA at room temperature was aspirated to measure the %DRBC, defined as the percentage of RBCs with a Hb concentration &amp;gt;1.11 mg/mL. Analysis: Patient characteristics were summarized using median with 25th and 75th percentiles, and frequency with percentage. Characteristics and labs were compared by group with t-test, Wilcoxon rank sum test, or Fisher's exact test. Receiver operating characteristics (ROC) analyses were performed to identify HbAS versus HbSS/Sβ0 for each biomarker. All analyses were performed using Stata 15. Results The EImin, EImax, PoS, and %DRBC differed significantly between the HbAS and HbSS/Sβ0 groups, despite including transfused, very young, and HU-treated samples in the HbSS/Sβ0 cohort (p&amp;lt;0.001, p=0.002, p&amp;lt;0.001, and p&amp;lt;0.001, respectively; Table 1). ROC analysis showed that a threshold Elmin greater than or equal to 0.453 identified HbAS with 94.12% sensitivity and 95.43% specificity. EImax greater or equal to 0.569 identified HbAS with 94.12% sensitivity and 81.57% specificity. PoS less than 21.38 mmHg identified HbAS with 93.87% sensitivity and 93.33% specificity. %DRBC less than 1.6% identified HbAS with 88.13% sensitivity and 88.00% specificity (Table 2). Conclusion Conventional laboratory testing may not be able to establish if gene-based therapy has achieved a cure. We propose to define a cure as achievement of an HbAS level of RBC quality in a gene-based therapy edited RBC population. We show that rheological biomarkers EImin, EImax, PoS, and %DRBC differ significantly between individuals with HbAS and HbSS/Sβ0 of all spectrums of severity and treatment regimens. Not only are the rheological biomarker values significantly different, but there is little to no overlap in ranges of values obtained from the different genotypes, even in heavily transfused HbSS patients, with HbS as low as 31%. EImin, EImax, PoS, and %DRBC functionally identify genotype with high sensitivity and specificity; we propose that they be used not to diagnose SCD, but to determine if a HbSS or HbSS/Sβ0 individual who has undergone successful gene-based therapy has achieved the RBC functionality of a HbAS individual. Disclosures van Beers: Novartis: Research Funding; Pfizer: Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees, Research Funding; RR mechatronics: Research Funding. Wijk:Agios Pharmaceuticals Inc.: Research Funding; RR mechatronics: Research Funding. Rab:RR Mechatronics: Research Funding. Sheehan:Global Blood Therapeutics: Research Funding; Novartis: Research Funding; Emmaus: Research Funding.

Incidence of hemoglobinopathies and diagnostic algorithm in newborns in the state of Mato Grosso do Sul

Introduction: Hemoglobinopathies are inherited disorders that affect the normal aspect of human hemoglobin (Hb). The disorders can be structural defect in one of globin subunits (variant hemoglobin) or reduction in the rate of globin chain synthesis (thalassemia). In this scenario, Hb S stands out as the most frequent hemoglobinopathy in the world and it’s responsible for sickle cell disease (SCD). HbS can be found in different combinations, resulting in extreme clinical conditions; it can range since a severe presentation - sickle cell anemia (HbSS) to asymptomatic - sickle cell trait (HbAS). Since 2013, screening for hemoglobinopathies has been covered by the National Neonatal Screening Program (NNSP) and aims to diagnose and intervene in cases of hemoglobinopathies in all Brazilian newborns. In view of the large amount of abnormal Hb described and the different combinations of hemoglobinopathy, the diagnosis is complex and involves a trained professional team.Objective: To evaluate the incidence of abnormal Hb in newborns (NBs) in the state of Mato Grosso do Sul (MS) and propose a hemoglobinopathies diagnostic algorithm for health services in order to outline the appropriate conduct, such as treatment or genetic orientation. Methodology. Cross-sectional, observational, descriptive and quantitative study, carried out between January 2019 and February 2020, involving 42,032 RNs from MS through the PNTN. Abnormal Hb samples were analyzed using electrophoretic, chromatographic techniques (HPLC-Ultra2 and Genesys, Trinity Biotech) and molecular techniques (PCE-RE and GAP- PCR) by Neonatal Screening Laboratory of MS and university laboratory. Results: It was found that 1070 newborns (mean age: 12.4 days) had abnormal Hb, with hemoglobin profiles: 792 (74%) HbFAS, 238 (22.2%) HbFAC, 12 (1.1%) HbFSA, 10 (0.9%) HbFCA, 7 (0.7%) HbFAD, 4 (0.4%) HbFS, 4 (0.4%) HbFSC, 1 (0.1%) FC and 2 (0.2%) other Hb profiles not detected.Discussion and Conclusion: The creation of a hemoglobinopathies diagnostic algorithm becomes a great ally of health services for early interventions, when it’s necessary. The initial evaluation by HPLC quick scan is important to differentiate, according to the profile presented at birth, normal phenotypes (HbFA) from abnormal ones. The distinct phenotypes of HbFA must be analyzed by HPLC high definition. In case of doubts regarding about the type of hemoglobinopathy, confirmatory tests should be performed using molecular biology, such as RFLP-PCR, PCR-AE, GAP-PCR and DNA sequencing. The data collected show us that the Hb S trait is the most incident, followed by the HbC trait; none of both have significant clinical repercussions. On the other hand, for symptomatologic cases, there is SCD patients of different genotypes (Hb SS, Hb SC and Hb S/Beta + thalassemia). Thus, the importance of a diagnostic algorithm capable of optimizing the diagnosis and reducing errors in the identification of hemoglobinopathies is endorsed, as well as serving as support for the implementation of prophylactic practices, referral to specialized treatment and genetic orientation to the family in these cases.

SO050DIFFERENT FERRIC CITRATE DOSE REGIMENS IN THE TREATMENT OF IRON DEFICIENCY ANAEMIA IN PATIENTS WITH NON-DIALYSIS-DEPENDENT CKD: THE COMPASS TRIAL

Abstract Background and Aims Ferric citrate (FC) is approved in the US as oral iron replacement for the treatment of iron deficiency anaemia (IDA) in adult patients with non-dialysis dependent (NDD) chronic kidney disease (CKD) and for the treatment of hyperphosphatemia in adult patients with dialysis dependent CKD. For IDA, a starting dose FC of 1 tablet three times daily (TID) is recommended with titration to maintain haemoglobin (Hb) at goal. This study was designed to investigate the possibility of dosing FC twice daily (BID) for flexibility in clinical practice. The efficacy and safety of different FC dosing regimens for the treatment of IDA were examined in adults with NDD-CKD. Method In this 48-wk, Phase 4, randomized, open-label, multicentre study, subjects with IDA of NDD-CKD (stage 3-5) were randomized 1:1 to receive 1 FC tablet (1gm containing 210mg ferric iron) TID or 2 tablets BID. At wk 12, subjects whose Hb increased &amp;lt;0.5 g/dL from baseline (BL) or was &amp;lt;10 g/dL had their dose increased to either 2 tablets TID or 3 tablets BID consistent with their original dosing regimen. This prespecified analysis reports data through wk 24. The primary endpoint was mean change in Hb from BL to wk 24. Secondary endpoints included mean change in transferrin saturation (TSAT), ferritin, and phosphate to wk 24. Results 206 subjects were randomized, 183 were included in this analysis after completing the 24-wk dose titration period. Groups were well matched with mean age of 69.5 +/- 10.32 years, 64% female and 54% had diabetes as a cause of CKD. Mean BL eGFR was 33.6 +/- 10.85 ml/min/1.73m2 and Hb 10.45 +/-0.744 g/dL. In subjects who did not require an increase in the FC dose at wk 12, mean changes in Hb at wk 24 were 1.05 and 1.24 g/dL in the 1 tablet TID and 2 tablet BID dosage groups, respectively. In subjects who required an increase in the FC dose at wk 12, mean changes in Hb at wk 24 were 0.41 and 0.13 g/dL in the 2 tablet TID and 3 tablet BID groups, respectively. Mean changes in TSAT, ferritin and phosphate are presented in the Table. The incidence of TEAEs was 78.2% and 75.0% in the BID and TID groups, respectively. The most common AEs reported were diarrhoea, stool discoloration and constipation. The incidence of SAEs was 13.9% and 17.3% in the BID and TID groups, respectively. Five deaths were reported, none were deemed related to FC per the investigator. Conclusion FC was effective and generally well tolerated in the treatment of IDA in this NDD-CKD population. Subjects who had per protocol FC dose increases at wk 12 had less pronounced iron deficiency at BL and smaller increases in Hb suggesting an additional underlying cause of anaemia. Mean changes in Hb, TSAT, ferritin, and phosphate and AE profiles were similar in the BID and TID regimens as well as in 3 g/day and 4 g/day dosing groups supporting the potential for dosing flexibility with FC. Clinicaltrials.gov identifier NCT03236246 Funding provided by Akebia Therapeutics, Inc.

The prevalence of sickle cell trait in Division I university athletics programs

ABSTRACT Objectives: To determine the prevalence of student-athletes with sickle cell trait (SCT) and describe their demographics, prior knowledge of status, and hemoglobin (Hb) profile. Methods: A retrospective chart review was conducted at two National Collegiate Athletic Association Division I universities. Participants were student-athletes during the 2010/11-2018/19 academic years. The independent variable was SCT status. Main outcome measures included actual prevalence of SCT positive student-athletes, sex, race, sport, prior knowledge of personal and family history SCT status, and Hb profile (HbA, HbA2, HbS, HbF, HbC) proportions. Results: Fifty-three SCT positive student-athletes (13.2 ± 2.0 per academic year) were identified, accounting for ~1% of the student-athlete population annually. The majority were Black/African-American (n = 49, 100.0%; 4 missing) and males (n = 44, 83.0%). Football had the majority (n = 28, 52.8%) of SCT student-athletes. Most student-athletes were unaware of their SCT status (n = 33, 62.3%). There was no difference between actual and expected prevalence of SCT student-athletes overall and by race in any academic year (p > 0.05). Results of Hb electrophoresis testing were available for 44 (83.0%) student-athletes. Average values for HbA, HbA2, HbS, HbF and HbC were 58.54 ± 4.26%, 3.42 ± 0.53%, 37.99 ± 4.60%, 0.17 ± 0.68% and 0.00 ± 0.00%, respectively. Conclusions: Student-athletes with SCT were a small proportion of the student-athlete population. The majority of SCT student-athletes had no prior knowledge of personal or family history; therefore, it is insufficient to rely on self-reported history. No difference was found between actual and expected prevalence of SCT student-athletes. Due to high proportion of student-athletes who are unaware of their SCT status, institutions should facilitate SCT screening with confirmatory testing for all student-athletes to prevent missed identification of those with SCT.

Hemoglobins F, A2 , and E levels in Laotian children aged 6-23 months with Hb E disorders: Effect of age, sex, and thalassemia types.

IntroductionDetermination of hemoglobins (Hbs) F, A2, and E is crucial for diagnosis of thalassemia. This study determined the levels of Hbs F, A2, and E in children aged 6‐23 months and investigated the effect of age, sex, and types of thalassemia on the expression of these Hbs.MethodsA total of 698 blood samples of Laotian children including 272 non‐Hb E, 271 Hb E heterozygotes, and 155 Hb E homozygotes were collected. Hb profiles were determined using the capillary zone electrophoresis. Coinheritance of α‐thalassemia and the homozygosity for Hb E mutation were checked by PCR‐based assay.ResultsChildren heterozygous and homozygous for Hb E had significantly higher Hb F and A2 levels than non‐Hb E children (median Hb F = 1.1% for non‐Hb E group, 2.7% for Hb E heterozygotes, and 9.4% for Hb E homozygotes; median Hb A2 = 2.6% for non‐Hb E group, 3.8% for Hb E heterozygotes, and 5.2% for Hb E homozygotes). The median Hb E levels were 21.9% for Hb E heterozygotes and 85.3% for Hb E homozygotes. Comparing within group, there was a statistically significant difference between children with and without an α‐gene defect for Hb A2 and E, but not Hb F. Based on a multiple regression analysis, age and sex were significantly associated with the expression of Hb F and A2 but not Hb E.ConclusionsOur findings can guide the development of a diagnostic approach to thalassemia in children aged 6‐23 months.

Rheological Assessments of Sickle Cell Patients Post Allogeneic Hematopoietic Cell Transplant

Introduction: Mixed donor chimerism (MDC) occurs in nearly 35% of patients with sickle cell disease (SCD) post allogeneic hematopoietic cell transplant (alloHCT). Donor myeloid engraftment of &amp;gt;20% is considered necessary to support disease resolution. However, in a disease known for its clinical variability, we hypothesize that patients (pts) with a severe pre-HCT phenotype may have abnormal RBC rheology at a level of chimerism and %HbS believed to be consistent with a cure. RBC rheology is markedly abnormal in SCD; these abnormalities are associated with SCD related clinical complications. Even fully oxygenated, sickle RBC are less deformable than those of HbAA or HbAS individuals; upon deoxygenation, deformability further declines. Sickle RBC morphology reflects the tendency to polymerize, with characteristic sickle forms. Sickle RBC are more adherent to the endothelial cell lining of the vasculature than HbAA or HbAS RBCs. The goal of any cell-based therapy of curative intent should be normalize the red cell rheology. To determine if the rheology of blood from SCD pts post-HCT with varying degrees of donor chimerism fall into the HbSS range of values, we propose to functionally assess the peripheral blood from a series of 6 post alloHCT SCD patients using a battery of rheological tests measuring deformability, sickling, adherence, percent dense cells (%DRBC), and RBC morphology. Methods: Peripheral blood samples (EDTA) from 6 SCD pts post alloHCT with a matched sibling donor were collected and immediately analyzed using oxygenscan (Lorrca), artificial microvascular network (AMVN), microfluidic image acquisition, and an ADVIA hematology analyzer. The Lorrca with oxygenscan measures RBC deformability (elongation index EI), under a range of pO2 (150-0 mmHg). EImax is the deformability of the oxygenated sickle RBC; EImin is the deformability of deoxygenated RBCs. The point of sickling (PoS) is the pO2 at which RBC deformability rapidly declines. RBC adhesiveness is measured by the difference in rate of perfusion of RBC through the AVMN coated with adhesive proteins (adherent AVMN) and a non-adherent, uncoated AVMN. %DRBC was measured by an ADVIA hematology analyzer. Microscopic RBC images were acquired and classified to determine the fraction of sickled RBCs in well-oxygenated samples. Additional clinical data including Hb profile, donor chimerism, and symptoms were obtained via chart review. Reference ranges were generated as described above using n=45 HbSS samples ages 2-21, on hydroxyurea, chronic transfusion, or untreated; n=14 HbAS, and n=43 HbAA. Results: In Figure 1, we show the measurements obtained by the Lorrca with oxygenscan on 5 pts post-alloHCT with a range of donor chimerism, as well as typical values for HbAA, HbAS, and HbSS patients. Patient 1 and 3 exhibit normal rheology; both were transplanted with a HbAA donor, with high chimerism and no detectable HbS. Patient 2 has 40% whole blood chimerism, well above the 20% threshold described with myeloid chimerism, and a HbS less than 50%, yet their plot resembles that of an untransplanted HbSS pt; the donor to Patient 2 exhibits the expected HbAA deformability. Patients 5 and 6 exhibit rheology in the HbAS range; they have intermediate chimerism from a HbAS donor. Clinical details and biomarker panel values for all 6 pts analyzed are in Table 1, as well as ranges of values for HbSS and HbAS subjects generated in the Sheehan and Shevkoplyas labs. Patient 2 is the only subject with values in the HbSS range, and the only subject with SCD symptoms. Conclusions: Our rheological tests identified a pt with values consistent with a HbSS pt of moderate severity or treated with hydroxyurea despite variable donor chimerism above the 20% threshold and HbS &amp;lt;50% thought to be sufficient for cure. The pt reported pain events beginning two years prior, indicating a clinical correlation supporting the validity of the rheological tests we propose to use to distinguish cure from persistent SCD. Current post-HCT evaluation depends on chimerism and hemoglobin profiles, and would not detect the significant functional abnormalities visible by Lorrca with oxygenscan biomarkers that indicate that Patient 2 is at risk for SCD related complications. Our results suggest that this functional analysis may help with management of post alloHCT SCD pts, and may be even more essential to assessing new gene-based therapy approaches to curing patients with SCD. Disclosures Rab: RR Mechatronics: Research Funding. van Wijk:Agios Pharmaceuticals: Consultancy, Research Funding; RR Mechatronics: Research Funding. Shevkoplyas:SSS: Research Funding; New Health Sciences: Consultancy.

A Novel α-Thalassemia Screening Scheme in Neonates with Higher Sensitivity and Specificity Using a Combination of Hb Bart's Quantity and Red Blood Cell Indices

Background: Besides detecting hemoglobin (Hb) variants such as sickle cell disease for early preventive measure, newborn screening (NBS) program using Hb profile could identify other forms of thalassemia (thal) and Hb disorders. Due to continuous expression of fetal Hb (γ globin chains), the presence of Hb Bart's (γ4) at birth caused by unbalanced α to β like-globin synthesis have been used to screen for α-thal. So far, this NBS approach appears to be the only laboratory evaluation of α-thal screening for both carriers and Hb H disease since soon after birth Hb Bart's level would decline and we can only use DNA analysis to identify α-thal traits. Neonatal screening of αº-thal due to two missing α-globin genes (–/αα or -α/-α) from normal four copies and Hb H disease (3 α-globin genes lost; –/-α) could be achieved by using the percentage of Hb Bart's cutoffs from isoelectric focusing (Jindatanmanusan P et al. 2014) or capillary electrophoresis (Suksangpleng T et al. ASH 2017). However this approach has a major limitation to screen for α+-thal trait both deletional (-α/αα) and non-deletional (αTα/αα) types due to rather low sensitivity and specificity.Objective: To develop a novel scheme for early detection of all types of α-thal using a combination of neonatal hematological parameters and Hb profiles at birthMethods: After informed consent approved by the local ethical committee, 0.3-ml EDTA whole blood samples and dried blood spot were collected within 48 hrs after birth in newborn delivered at Siriraj Hospital by heel prick puncture. We measured the complete blood count (CBC) by using Unicel® DxHTM800 Coulter® Cellular Analysis System (Beckman Coulter, Brea, USA). The gDNA was also extracted for PCR-based molecular analysis to detect > 98% of α- and β-globin mutations mostly found in Thailand. Neonatal Hb profile was measured in qualitative and quantitative analysis using Capillarys 2 NEONAT FAST® (SEBIA, Évry, France). All data from each genotype groups were statistically analyzed using PASW statistics 18 Software (SPSS Inc, 2015).Results: Total 732 healthy Thai neonates consisted of normal α-globin alleles (αα/αα; n=505, 69%), α+-thal carrier (-α/αα; n=139, 19%), non-deletional α-thal carrier (αTα/αα, n=33, 4.5%), α°-thal carrier (–/αα) and homozygous α+-thal (-α/-α; n=43, 5.9%), compound heterozygous α+-thal with non-deletional type (-α/αTα; n=8, 1%), and Hb H disease (–/-α; n=4, 0.6%). This population had normal β-globin genotype (ββ; n=533, 72.8%), Hb E carrier (βEβ; n=183, 25%) and homozygous Hb E (βEβE; n=16, 2.2%). Interestingly, red cell indices (MCV and MCH) and Hb Bart's levels were significantly altered due to different α-globin genotypes but not by Hb E coinheritance, gender, gestational age or history of neonatal jaundice. These suggested that the variation of red cell indices at birth is largely dependent on the number of expressed α-globin genes. Therefore we hypothesized that by using a combination of red cell indices and Hb Bart's level, we could improve the efficiency of α-thal screening at birth. Indeed, we have identified several cutoffs of Hb Bart's, MCV and MCH by using a ROC analysis that could differentiate individuals with different defective α-globin genes (data not shown). We have developed a range of cutoffs and in combination using either MCV or MCH as a first screening tool followed by Hb Bart's levels, the sensitivity and specificity of α-thal screening could significantly increase (Figure 1A and B). Moreover, we previously showed the 30% sensitivity and 94% specificity to detect α+-thal trait by using Hb Bart's cutoff alone. Interestingly, our approach can increase both sensitivity and specificity up to >90%. This was also true for other types of α-genotypes (Table 1). This novel approach has a significant impact on screening for both deletional and non-deletional α+-thal traits (-α and αTα).Conclusion: For the first time, this novel combined screening using either MCV or MCH together with Hb Bart's could be used to detect all types of α-thal with a very high sensitivity (>85%) and specificity (100%). This approach would be useful to identify individuals with α-thal as a part of our national program for prevention and control of thalassemia disease currently operating in Thailand. Moreover our recommended screening flow described herein would be useful for other Southeast Asian countries where more than 30% of population is affected by α-thal. [Display omitted] DisclosuresViprakasit:Agios: Consultancy, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Protagonist Therapeutics: Consultancy, Research Funding.

Universal Screening Program in Pregnant Women and Newborns at-Risk for Sickle Cell Disease: First Report from Northern Italy

The implementation of screening programs for early detection of patients with sickle cell disease has become necessary in Italy as a result of the high rate of migration from areas with a high prevalence of the disease (Sub-Saharan Africa, Middle East and the Balkans). Following a pilot study performed in the province of Modena, Italy in 2011–2013, an official screening program was established on May 31 2014 for all pregnant women, free-of-charge for the family according to the National Guidelines for Physiological Pregnancy. Hemoglobin (Hb) profiles of pregnant women within 10 weeks of pregnancy, of new mothers at delivery and of the newborns of mothers with variant Hb profiles (newborns at-risk), were evaluated by high performance liquid chromatography (HPLC). Samples from 17,077 new mothers were analyzed and 993 showed alteration of Hb patterns (5.8%) (1.0% Hb AS carriers); of the 1011 at-risk newborns, four (0.4%) carried sickle cell disease and 90 (8.9%) were Hb AS carriers. These data show that early diagnosis of sickle cell disease or carrier status can be obtained in high-risk newborns, providing valuable information on the frequency of these conditions in geographic areas in which the disease is historically rare.

Hemoglobin Variant Profiles among Brazilian Quilombola Communities

Brazilian Quilombolas are communities composed of African-derived populations that have their territories guaranteed by the Brazilian Constitution. The present study investigated the hemoglobin (Hb) variants among these population groups. This study was conducted in a total of 2843 individuals of Brazilian Quilombola communities of the Bahia, Pará, and Piauí states. All the participants had their Hb profiles evaluated. The Hb S (HBB: c.20A>T) variant was described in all the studied localities. However, the individuals in Bahia State had the highest frequency of the Hb C (HBB: c.19G>A) variant; individuals from Piauí State had a higher frequency of the Hb D-Punjab (HBB: c.364G>C) variant compared to the other states, and individuals from Pará State only carried the Hb S variant. The present study revealed a specific distribution of Hb variants that could represent different waves of African influence in these Brazilian populations.

Serum Haptoglobin and Hemopexin Levels in Pediatric SS and SC Disease Patients: Biomarker of Hemolysis and Inflammation

▪INTRODUCTION: Hemolysis is a hallmark of sickle cell disease (SCD) pathogenesis, with the release of hemoglobin (Hb) and heme into the plasma that can promote vasculopathy, inflammation, thrombosis, and renal injury. Plasma haptoglobin (Hp) and hemopexin (Hpx) tightly bind free Hb and heme, respectively, thwarting these clinical sequelae. Hp-Hb and Hpx-heme complexes bind to CD163 and CD91 receptors found primarily on macrophages and hepatocytes, respectively, and are taken up by receptor-mediated endocytosis. In SCD patients it is generally believed that chronic hemolysis depletes plasma haptoglobin and hemopexin levels, however we found only one paper in the literature that has reported plasma Hp and Hpx levels in SCD patients, albeit in a limited number of SS (n=5) and SC (n=3) patients (Muller-Eberhard U et al. Blood 1968). Here we report serum Hp and Hpx levels in 272 Brazilian SS, SC, and AA children along with systemic biomarkers of hemolysis, iron metabolism, inflammation leukocyte and platelet counts, and lipid metabolism. We hypothesize that serum Hp and Hpx levels will be significantly lower and biomarkers of hemolysis, iron metabolism, and inflammation will be significantly higher in SS and SC children compared to AA children. METHODS: The present study used blood samples collected prospectively from 272 unrelated steady-state SCD children with SS (n=179) and SC (n=93) disease. Patients were followed at Bahia Pediatrics Centers, during January 2010 to November 2015. The study included 28 healthy AA volunteers randomly selected from the Clinical Laboratory of the Faculdade de Farmácia da Universidade Federal da Bahia. The study was approved by the Fundação de Pesquisa Oswaldo Cruz research board, and all procedures were in accordance with the Declaration of Helsinki of 1975, as revised in 2000. Biochemical and inflammatory analyses were performed by immunochemistry assay and immunoassay. Hematological analyses were carried out using an electronic cell counter and the Hb profile was investigated by high performance liquid chromatography. Serum Hp and Hpx levels were measured by enzyme-linked immunoassay following the manufacturer’s instructions. RESULTS: Evaluating the Hp and Hpx levels, we found that SS and SC patients have lower Hp and Hpx levels (SS<SC<AA) than AA controls (p<.001, Table 1). Similarly, SS and SC patients have lower hemoglobin and hematocrits (SS<SC<AA) and increased reticulocyte counts and serum LDH (SS>SC>AA) than AA controls (p<.001, Table 1). Total, direct, and indirect bilirubin, markers of heme degradation, followed a similar pattern (SS>SC>AA, p<.001, Table 1). These data may reflect more intravascular hemolysis in the following pattern: SS>SC>AA. Likewise, serum ferritin levels, a marker of body iron stores, were higher in SS and SC patients than AA controls (SS>SC>AA, p<.001, Table 1). CRP levels and white blood cells count, markers of inflammation, also reflected the same pattern (SS>SC>AA, p<.001, Table 1). In a different pattern, platelet counts were highest in SS patients and lowest in SC patients (SS>AA>SC). Finally, Total, HDL, and LDL cholesterol levels were lowest in patients with more hemolysis (SS<SC<AA, p<.001, Table 1). CONCLUSIONS: We report lower levels of Hp and Hpx in children with SCD (SS<SC<AA). These data support Muller-Eberhard’s 1968 brief report on Hp and Hpx levels in hemolytic conditions and demonstrate significant correlations of serum Hp and Hpx with biomarkers of hemolysis, inflammation, and cholesterol. We speculate that serum Hp and Hpx levels in SCD may serve as clinical indicators of hemolysis, inflammation, and disease severity. [Display omitted] DisclosuresVercellotti:Imara: Research Funding. Belcher:Cydan/Imara: Research Funding; CSL-Behring: Research Funding.

Pre-Treatment Steady-State Rheology Predicts Response to Hydroxyurea in Patients with Sickle Cell Disease

Background: Patients with sickle cell disease (SCD) have altered blood rheology due to erythrocyte abnormalities, such as increased aggregation and RBC density. The hematocrit to viscosity ratio (HVR) is a measure of RBC oxygen carrying capacity, and is reduced in SCD. Higher percent dense red blood cells (%DRBC) and lower HVR have been associated with higher rates of disease related complications. The aim of this study was to elucidate the effects of hydroxyurea (HU), fetal hemoglobin (HbF) and transfusion therapy (TF) on the rheology of patients with SCD.Methods: We measured whole blood viscosity of samples from children with SCD at low shear (45 s-1) and high shear (225 s-1) using a Brookfield cone and plate viscometer under oxygenated conditions. Venous blood samples in EDTA were analyzed within 4 hours of phlebotomy. Laboratory values were obtained with a Siemens ADVIA120 Hematology System; Hb profiles by high performance liquid chromatography. Samples were collected at routine clinic visits from SCD patients prior to initiation of therapy (n=105 for HbSS, n=77 for HbSC), then on HU at MTD, (n=30 for HbSS, n=13 for HbSC), or at least one week after TF (n=32). A paired T-test was used to assess treatment changes; correlation/trend tests were used to test association of hematological and rheology parameters. Results: Blood viscosities at low and high shear rates were significantly higher in untreated patients with HbSC compared to untreated patients with HbSS (p<0.001), while HVR was similar between patients with HbSC or HbSS. High endogenous HbF levels were significantly associated with higher HVR 225 s-1 in patients with HbSS but not HbSC. Patients with HbSS after TF had a significant improvement (rise) in their HVR at high shear (p=0.04) but not at low shear. This TF mediated rise in HVR 225 s-1 correlated with increased Hb (r=0.56, p<0.002), and decreased WBC and ANC (r= - 0.46 and r=- 0.36 respectively, p<0.05). Patients with greatest decreases in %HbS had most improvement in their HVR 225 s-1 (r = -0.36, p=0.15). HbSS patients treated with HU also had a rise in their HVR 225 s-1 (p=0.01) but not HVR 45 s-1. This improved HVR 225 s-1 was associated with typical HU induced changes in Hb, Hct, HbF and decreases in WBC and ANC.For HbSS patients treated with either HU or TF, a baseline HVR (at either shear rate) below the group mean experienced a greater rise in HVR, while a baseline HVR above the mean experienced a decline (p<0.001; Figure 1). HbSS patients with a pre-treatment %DRBC above the mean experienced a decline in %DRBC on HU at MTD, while those with a %DRBC below the mean did not (p=0.001).A similar trend was seen in HbSC patients treated with HU to MTD, but did not reach statistical significance.Patients with HbSC had significantly higher %DRBC compared to patients with HbSS (p<0.001). HbSC patients placed on HU had significantly higher baseline %DRBC than HbSC patients not treated with HU (15.8 ±13 versus 8.2± 6.5, p=0.001). However, HbSC patients treated to HU MTD did not experience a significant reduction in %DRBC. Individuals with HbSS and high endogenous HbF had significantly lower %DRBC (r= -0.36, p=0.002), and greater production of HbF on HU also resulted in lower %DRBC (p=0.036) in HbSS (n=25), but not HbSC patients (n=13).Conclusions: In HbSS patients, high endogenous HbF levels were significantly associated with higher HVR at high shear and with lower %DRBC, but not in HbSC patients. In HbSS patients, HU and TF therapy improved HVR at high shear rates but not low shear, possibly indicating persistent red cell adhesion at low shear rates. This improvement correlated with HbF levels in HU treated patients, and HbS levels in TF treated patients. Patients with SCD and greater than average impairment of whole blood rheology at pre-treatment steady-state experienced greater rheological improvement, demonstrated clinically by a reduction in %DRBC or a rise in HVR on HU. A cohort of 13 HbSC patients treated prospectively with HU did not demonstrate statistically significant rheological improvement, either a result of small sample size or the minimal rise in HbF despite HU therapy. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.