A Novel Algorithm Using Cell Population Data (VCS Parameters) as a Screening Discriminant between Alpha and Beta Thalassemia Traits

Thalassemia is one of the major inherited haematological disorders in the Southeast Asia region. This study explored the potential utility of red blood cell (RBC) parameters and reticulocyte cell population data (CPD) parameters in the differential diagnosis of α and β-thalassaemia traits as a rapid and cost-effective tool for screening of thalassemia traits. In this study, a total of 1597 subjects (1394 apparently healthy subjects, 155 subjects with α-thalassaemia trait, and 48 subjects with β-thalassaemia trait) were accrued. The parameters studied were the RBC parameters and reticulocyte CPD parameters derived from Unicel DxH800. A novel algorithm named αβ-algorithm was developed: (MN-LMALS-RET × RDW) − MCH) to discriminate α from β-thalassaemia trait with a cut-off value of 1742.5 [AUC = 0.966, sensitivity = 92%, specificity = 90%, 95% CI = 0.94–0.99]. Two prospective studies were carried: an in-house cohort to assess the specificity of this algorithm in 310 samples comprising various RBC disorders and in an interlaboratory cohort of 65 α-thalassemia trait, and 30 β-thalassaemia trait subjects to assess the reproducibility of the findings. We propose the αβ-algorithm to serve as a rapid, inexpensive surrogate evaluation tool of α and β-thalassaemia in the population screening of thalassemia traits in geographic regions with a high burden of these inherited blood disorders.

The Post-Storage Performance of RBCs from Beta-Thalassemia Trait Donors Is Related to Their Storability Profile

Blood donors with beta-thalassemia traits (βThal+) have proven to be good “storers”, since their stored RBCs are resistant to lysis and resilient against oxidative/proteotoxic stress. To examine the performance of these RBCs post-storage, stored βThal+ and control RBCs were reconstituted in plasma donated from transfusion-dependent beta-thalassemic patients and healthy controls, and incubated for 24 h at body temperature. Several physiological parameters, including hemolysis, were evaluated. Moreover, labeled fresh/stored RBCs from the two groups were transfused in mice to assess 24 h recovery. All hemolysis metrics were better in the group of heterozygotes and distinguished them against controls in the plasma environment. The reconstituted βThal+ samples also presented higher proteasome activity and fewer procoagulant extracellular vesicles. Transfusion to mice demonstrated that βThal+ RBCs present a marginal trend for higher recovery, regardless of the recipient’s immune background and the RBC storage age. According to correlation analysis, several of these advantageous post-storage characteristics are related to storage phenotypes, like the cytoskeleton composition, low cellular fragility, and enhanced membrane proteostasis that characterize stored βThal+ RBCs. Overall, it seems that the intrinsic physiology of βThal+ RBCs benefits them in conditions mimicking a recipient environment, and in the circulation of animal models; findings that warrant validation in clinical trials.

Application of Bayesian Decision Tree in Hematology Research: Differential Diagnosis of β-Thalassemia Trait from Iron Deficiency Anemia

Objective. Several discriminating techniques have been proposed to discriminate between β-thalassemia trait (βTT) and iron deficiency anemia (IDA). These discrimination techniques are essential clinically, but they are challenging and typically difficult. This study is the first application of the Bayesian tree-based method for differential diagnosis of βTT from IDA. Method. This cross-sectional study included 907 patients with ages over 18 years old and a mean (±SD) age of 25 ± 16.1 with either βTT or IDA. Hematological parameters were measured using a Sysmex KX-21 automated hematology analyzer. Bayesian Logit Treed (BLTREED) and Classification and Regression Trees (CART) were implemented to discriminate βTT from IDA based on the hematological parameters. Results. This study proposes an automatic detection model of beta-thalassemia carriers based on a Bayesian tree-based method. The BLTREED model and CART showed that mean corpuscular volume (MCV) was the main predictor in diagnostic discrimination. According to the test dataset, CART indicated higher sensitivity and negative predictive value than BLTREED for differential diagnosis of βTT from IDA. However, the CART algorithm had a high false-positive rate. Overall, the BLTREED model showed better performance concerning the area under the curve (AUC). Conclusions. The BLTREED model showed excellent diagnostic accuracy for differentiating βTT from IDA. In addition, understanding tree-based methods are easy and do not need statistical experience. Thus, it can help physicians in making the right clinical decision. So, the proposed model could support medical decisions in the differential diagnosis of βTT from IDA to avoid much more expensive, time-consuming laboratory tests, especially in countries with limited recourses or poor health services.

Base Editing Repairs the HbE Mutation Restoring the Production of Normal Globin Chains in Severe HbE/β-Thalassemia Patient Hematopoietic Stem Cells and Erythroid Cells

HbE/β-thalassemia is the commonest form of severe β-thalassemia, and comprises approximately 50% of all cases worldwide. HbE/β-thalassemia is caused by the HbE codon 26 G>A mutation on one allele and any severe β 0-thalassemia mutation on the other. These mutations lead to a reduction in β-globin production, resulting in a relative excess in α-globin chains that go on to cause ineffective erythropoiesis. Importantly, individuals with a mutation on one, but not two, alleles have β-thalassemia trait, a carrier state with a normal phenotype. Recent gene therapy and gene editing approaches have been developed to treat β-thalassemia but do not directly repair the causative mutation in-situ. Gene replacement approaches rely on lentiviral vector-based sequence insertion or homology directed repair (HDR). HbF induction strategies also rely on non-homologous end joining (NHEJ) targeting of enhancers in-trans. These approaches, whilst variably successful, are associated with potential safety concerns. Adenine base editors (ABEs) potentially circumvent these problems by directly repairing pathogenic variants in-situ through deamination. ABEs catalyse A-T to G-C conversions through targeting with a Cas9-nickase and single-guide RNA (sgRNA). Conversion of the HbE codon to normal through base editing is an attractive strategy to recapitulate the phenotypically normal β-thalassemia trait state without potentially harmful double-strand breaks or random vector insertions (Figure 1A). ABEs are able to convert the HbE codon (AAG, lys) to wild-type (GAG, glu), but also to GGG (gly) or AGG (arg). GGG at codon 26 is found in a naturally occurring hemoglobin, Hb Aubenas. Heterozygotes have normal red cell indices and are phenotypically normal. We electroporated the latest generation of ABE8 editors (ABE8e, ABE8.13 and ABE8 V106W) as mRNA into WT CD34+ hematopoietic stem and progenitor cells (HSPCs) with sgRNAs targeting the middle A of the WT GAG codon. These had similar editing efficiencies although ABE8 V106W had marginally higher on-target efficiency. V106W has been evolved to have a favourable off-target profile. V106W mRNA/sgRNA was electroporated into 3 different severe HbE/β-thalassemia donor HSPCs. The HbE codon was converted to WT with a mean 28.7% efficiency, to Hb Aubenas 48.6% and to an undescribed AGG codon 2.1%. The mean conversion from HbE to a normal or normal variant was 78.7±8.7% (Figure 1B). The indel rate from inadvertent on-target Cas9 cleavage was below 0.5%. Edited cells did not show any perturbations in erythroid differentiation as assessed by Immunophenotyping and cellular morphology. In differentiated erythroid cells, RT-qPCR showed a mean fall in the α/β mRNA ratio to 0.65±0.08 (unedited patient cells normalised to 1, n=5, Figure 1C), indicating a reduction in the relative excess α-globin gene expression. Protein analysis by CE-HPLC showed a 3.6-fold reduction in HbE levels (SD±1.3) and a 13.5-fold increase in HbA/Hb Aubenas (SD±2.4, Figure 1C and D). To prove that base editing using mRNA was possible in long-term HSCs, CD34+ cells from 4 WT cord blood donors were edited using ABEmax. Mice were culled after 16 weeks, and human cells were collected and transplanted into 7 secondary mice, which were also culled after 16 weeks. Each secondary mouse showed the presence of hCD45+ cells, indicating engraftment of LT-HSCs. All secondary replicates showed editing, with a mean editing efficiency of 34.5% (initial editing 46.3%). In both rounds of mice, there was robust lymphoid and myeloid engraftment and expected levels of erythroid engraftment for the NSG model in bone marrow and spleen. Potential off-target effects were assessed in-vitro by CIRCLE-seq in triplicate. These sites were assessed by targeted oligonucleotide capture of DNA from mRNA edited patient cells to detect in-vivo editing. Together these data provide robust evidence for base editing as an effective and safe therapeutic strategy for HbE/β-thalassemia. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Hydroxyurea Reduces the Transfusion Burden in Children with Sickle Cell Anemia: The Reach Experience

Introduction: Many children with sickle cell anemia (SCA) require blood transfusions, which carry risks and utilize a scarce resource globally, particularly in Africa. Realizing Effectiveness Across Continents with Hydroxyurea (REACH, NCT01966731) has documented the safety, feasibility, and benefits of hydroxyurea for children with SCA living in sub-Saharan Africa. In REACH, hydroxyurea escalated to maximum tolerated dose (MTD) significantly decreased vaso-occlusive events, malaria, and death; transfusions were decreased by ~70% over 30 months of treatment when compared to the 2-month screening period. Characterizing how hydroxyurea reduces transfusion needs in REACH could contribute to improved clinical understanding and lead to better outcomes, a decreased transfusion burden, and preservation of the blood supply in these limited-resource settings. Methods: Transfusions were recorded prospectively in the REACH REDCap electronic database. Using time-varying predictors and landmark analysis, transfusions during screening and treatment were analyzed by clinical site, calendar month, age, gender, splenomegaly, hydroxyurea dose, MTD status, baseline and latest laboratory values (Hemoglobin, MCV, HbF, absolute neutrophil count, and platelets, all measured at least 30 days prior to the transfusion), alpha thalassemia trait, and G6PD deficiency. Incidence rate ratios (IRR) were calculated for treatment periods compared to screening. Univariate relationships were assessed using the Anderson-Gill model, plus multiple regression to estimate Hazard Ratios (HR) with 95% confidence intervals (CI's). Results: A total of 635 children with SCA enrolled in REACH, and 606 started hydroxyurea treatment. During screening, 48 transfusions were given to 43 children, and during the treatment phase 405 transfusions were administered to 214 children over an average treatment time of 5.2 ± 1.3 years. The transfusion rate was 43.3 per 100 patient-years during screening, which decreased to 22.0 per 100 patient-years during the initial fixed dose treatment period (IRR = 0.50; 95%CI = 0.35-0.74, p<0.001 compared to screening) and then decreased further to 12.1 per 100 patient-years during the dose escalation period (IRR = 0.28; 95%CI = 0.21-0.39, p<0.001 compared to screening; IRR = 0.54; 95%CI = 0.43-0.73, p<0.001 compared to fixed-dose). For every 100 children treated for a year with hydroxyurea during dose escalation, there were 31.4 fewer transfusions compared to the untreated screening period. Comparison of the indications for transfusion between the screening and treatment periods revealed transfusions administered for anemia decreased from a rate of 26.1 to 5.1 per 100 patient-years (p<0.001), while transfusions for malaria trended toward a decrease from 7.2 to 3.8 per 100 patient-years (p=0.08). Lower transfusion rates on hydroxyurea were associated with higher hemoglobin concentration (HR = 0.72 per 1g/dL increase; 95%CI = 0.65-0.78, p <0.0001) and higher HbF levels (HR = 0.80 per 10% increase, 95%CI = 0.69-0.92, p=0.0071). Those with palpable splenomegaly had higher transfusion rates (HR = 1.58, 95%CI = 1.22-2.03, p=0.0094). Age, gender, alpha thalassemia trait, G6PD deficiency, and neutrophil count were not associated with differences in transfusion rates. Conclusion: Hydroxyurea significantly reduces blood transfusion administration in children with SCA in sub-Saharan Africa, especially when escalated to MTD. Transfusions for the sole indication of anemia decreased significantly on hydroxyurea treatment, likely due to higher treatment-associated hemoglobin levels and decreased hemolysis, and transfusions for malaria also trended toward a decrease. Splenomegaly remains a risk factor for transfusions despite hydroxyurea treatment. Overall, increased access to and implementation of hydroxyurea treatment for children with SCA across sub-Saharan Africa may not only improve individual patient outcomes through reduction in anemia, transfusion burden, and transfusion-associated complications including infections, but may also to help preserve the scarce blood supply for the benefit of the larger population. Disclosures Aygun: Global Blood Therapeutics: Consultancy; Patient Centered Outcomes Research Institute: Research Funding; National Heart, Lung, Blood Institute: Research Funding; National Institute of Nursing Research: Research Funding; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding. Stuber: ASH Research Collaborative: Consultancy. Ware: Bristol Myers Squibb: Research Funding; Addmedica: Research Funding; Hemex Health: Research Funding; Nova Laboratories: Research Funding; Novartis: Other: DSMB Chair; Editas: Other: DSMB Chair.

Genetic heterogeneity of beta thalassemia mutations in Kahramanmaraş province in Southern Turkey: preliminary report

Background: Beta thalassemia is one of the most common autosomal single-gene disorders in the world. The prevalence of the disease is in the “thalassemia belt” which includes the Mediterranean region of Turkey; throughout the country the gene frequency is estimated to be 2.1%, but in certain regions, this figure increases to 10%. Aim: In this first study, we aimed to determine the frequency of β-thalassemia trait and distrubition of mutations in Kahramanmaraş province, which is located in the southern part of Turkey. Materials and Methods: In this study; 5 ml blood samples was taken from 14 thalassemic patients and their relatives who were taking care of Sutcu Imam University Hospital at Kahramanmaraş. Also, we collected blood samples from 245 adults for screening beta thalassemia trait. Haematological data were obtained by cell counter.  HbA2 was determined by HPLC. Ten common mutations were screened by ARMS  (Amplification Refractory Mutation System) method. These β-thalassemia mutations are -30 (T>A), Fsc8 (-AA), Fsc8/9 (+G), IVS1-1 (G>A), IVS1-5 (G>C), IVS1-6 (T>C), IVS1-110 (G>A ), Cd 39 ( C>T), IVS2-1 (G>A), IVS 2-745 (C>G). A rare mutation; Fsc44 (-C) was charecterized by DNA sequencing. Results: Ten patients were detected as homozygous for IVS1-110 (seven cases), Fsc 44 (two cases) and IVS1-5 (only one case). Rest of the 4 patients were double heterozygous (two: IVS1-110/IVS1-6, one: Fsc8/Fsc8-9, one: IVS2-1/IVS1-5). In 245 adult, five  β-thalassemia trait were detected by screening survey.  Conclusion: Sixteen alleles were detected as IVS1-110 in 57.1%. It was seen the most common mutation in Kahramanmaraş. Seven different β-thalassemia mutations were found in this study. Each of 10 families have only one thalassemic patient, other two families have double thalassemic patient in total 12 family.

Blood Rheological Characterization of β-Thalassemia Trait and Iron Deficiency Anemia Using Front Microrheometry

The purpose of this work is to develop a hematocrit-independent method for the detection of beta-thalassemia trait (β-TT) and iron deficiency anemia (IDA), through the rheological characterization of whole blood samples from different donors. The results obtained herein are the basis for the development of a front microrheometry point-of-care device for the diagnosis and clinical follow-up of β-TT patients suffering hematological diseases and alterations in the morphology of the red blood cell (RBC). The viscosity is calculated as a function of the mean front velocity by detecting the sample fluid-air interface advancing through a microfluidic channel. Different viscosity curves are obtained for healthy donors, β-TT and IDA samples. A mathematical model is introduced to compare samples of distinct hematocrit, classifying the viscosity curve patterns with respect to the health condition of blood. The viscosity of the fluid at certain shear rate values varies depending on several RBC factors such as shape and size, hemoglobin (Hb) content, membrane rigidity and hematocrit concentration. Blood and plasma from healthy donors are used as reference. To validate their potential clinical value as a diagnostic tool, the viscosity results are compared to those obtained by the gold-standard method for RBC deformability evaluation, the Laser-Optical Rotational Red Cell Analyzer (LoRRCA).

Indices in differentiating iron deficiency anemia from thalassemia trait- a comparative study

Background: Iron deficiency anemia (IDA) and beta thalassemia trait (BTT) are the two most common and important causes of microcytic hypochromic anemia in India. It is very difficult to differentiate between the two. Many different types of techniques have been proposed for the same. While some are invasive like bone marrow examination others are not available at all centers, like electrophoresis. Hence different indices come into play. Aims and Objective: This study was undertaken to compare the efficacy of Shine and Lal index and Mentzer index in differentiating between IDA and BTT. Materials and Methods: A total of 407 anemia cases were studied over a period of 18 months and their blood samples were subject to different hematological and biochemical assays to diagnose the type of anemia. Results: Based on these tests 92.1% cases were found to be of IDA whereas 3.7% cases were found to be of BTT. Then both the indices were applied in the above mentioned cases. Conclusion: While Shine and Lal index was found to have better sensitivity, Mentzer index was found to have better specificity.