Use of Laser Assisted Optical Rotational Cell Analyzer (LoRRca MaxSis) in the Diagnosis of RBC Membrane Disorders, Enzyme Defects, and Congenital Dyserythropoietic Anemias: A Monocentric Study on 202 Patients

Designing a single-arm phase 2 clinical trial of mitapivat for adult patients with erythrocyte membranopathies (SATISFY): a framework for interventional trials in rare anaemias - pilot study protocol

INTRODUCTION

Membranopathies encompass haemolytic disorders arising from genetic variants in erythrocyte membrane proteins, including hereditary spherocytosis and stomatocytosis. Congenital dyserythropoietic anaemia type II (CDA II) is associated with the SEC23B gene and can exhibit phenotypic similarities to membranopathies. Current treatment options for these conditions, apart from splenectomy, are primarily supportive. Mitapivat, a novel pyruvate kinase (PK) activator, has demonstrated efficacy in increasing haemoglobin levels and reducing haemolysis in patients with PK deficiency, thalassemia, sickle cell disease and a mouse model of hereditary spherocytosis.

METHODS AND ANALYSES

Safety and efficacy of mitapivat sulfate in adult patients with erythrocyte membranopathies (SATISFY) is a prospective, multicentre, single-arm phase two trial involving approximately 25 adult patients (≥18 years) diagnosed with a membranopathy or CDA II. During the 8-week dose escalation period, subjects will receive an initial dose of 50 mg mitapivat two times per day and may increase to 100 mg two times per day at week 4 based on the safety and changes in haemoglobin levels. Patients tolerating mitapivat well may be eligible to continue in two consecutive 24-week fixed dose periods.The primary objective of this study is to evaluate the safety of mitapivat, assessed through the occurrence of treatment-emergent adverse events. Secondary objectives include assessing the effects of mitapivat on haemoglobin levels, haemolysis, erythropoiesis, patient-reported outcome measures and spleen size.SATISFY aims to assess the safety and efficacy of mitapivat in adult patients with red blood cell membranopathies and CDA II, with the aim of establishing proof-of-concept in patients living with these rare conditions.

ETHICS AND DISSEMINATION

NCT05935202/CTIS:2023-503271-24-01. Findings will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov, NCT05935202. CTIS:2023-503271-24-01. Registered 07-July-2023. Protocol number: 2.1. https://clinicaltrials.gov/study/NCT05935202.

Osmotic gradient ektacytometry - a novel diagnostic approach for neuroacanthocytosis syndromes

Introduction

The unique red blood cell (RBC) properties that characterize the rare neuroacanthocytosis syndromes (NAS) have prompted the exploration of osmotic gradient ektacytometry (Osmoscan) as a diagnostic tool for these disorders. In this exploratory study, we assessed if Osmoscans can discriminate NAS from other neurodegenerative diseases.

Methods

A comprehensive assessment was conducted using Osmoscan on a diverse group of patients, including healthy controls (n = 9), neuroacanthocytosis syndrome patients (n = 6, 2 VPS13A and 4 XK disease), Parkinson's disease patients (n = 6), Huntington's disease patients (n = 5), and amyotrophic lateral sclerosis patients (n = 4). Concurrently, we collected and analyzed RBC indices and patients' characteristics.

Results

Statistically significant changes were observed in NAS patients compared to healthy controls and other conditions, specifically in osmolality at minimal elongation index (Omin), maximal elongation index (EImax), the osmolality at half maximal elongation index in the hyperosmotic part of the curve (Ohyper), and the width of the curve close to the osmolality at maximal elongation index (Omax-width).

Discussion

This study represents an initial exploration of RBC properties from NAS patients using osmotic gradient ektacytometry. While specific parameters exhibited differences, only Ohyper and Omax-width yielded 100% specificity for other neurodegenerative diseases. Moreover, unique correlations between Osmoscan parameters and RBC indices in NAS versus controls were identified, such as osmolality at maximal elongation index (Omax) vs. mean cellular hemoglobin content (MCH) and minimal elongation index (EImin) vs. red blood cell distribution width (RDW). Given the limited sample size, further studies are essential to establish diagnostic guidelines based on these findings.

Testosterone supplementation increases red blood cell susceptibility to oxidative stress, decreases membrane deformability, and decreases survival after cold storage and transfusion

BACKGROUND

Blood collection from donors on testosterone therapy (TT) is restricted to red blood cell (RBC) concentrates to avoid patient exposure to supraphysiological testosterone (T). The objective of this study was to identify TT-related changes in RBC characteristics relevant to transfusion effectiveness in patients.

STUDY DESIGN

This was a two-part study with cohorts of patients and blood donors on TT. In part 1, we conducted longitudinal evaluation of RBCs collected before and at three time points after initiation of T. RBC assays included storage and oxidative hemolysis, membrane deformability (elongation index), and oximetry. In part 2, we evaluated the fate of transfused RBCs from TT donors in immunodeficient mice and by retrospective analyses of NIH's vein-to-vein databases.

RESULTS

TT increased oxidative hemolysis (1.45-fold change) and decreased RBC membrane deformability. Plasma free testosterone was positively correlated with oxidative hemolysis (r = .552) and negatively correlated with the elongation index (r = -.472). Stored and gamma-irradiated RBCs from TT donors had lower posttransfusion recovery in mice compared to controls (41.6 ± 12 vs. 55.3 ± 20.5%). Recipients of RBCs from male donors taking T had 25% lower hemoglobin increments compared to recipients of RBCs from non-TT male donors, and had increased incidence (OR, 1.80) of requiring additional RBC transfusions within 48 h of the index transfusion event.

CONCLUSIONS

TT is associated with altered RBC characteristics and transfusion effectiveness. These results suggest that clinical utilization of TT RBCs may be less effective in recipients who benefit from longer RBC survival, such as chronically transfused patients.

Current Status of Molecular Diagnosis of Hereditary Hemolytic Anemia in Korea

Hereditary hemolytic anemia (HHA) is considered a group of rare hematological diseases in Korea, primarily because of its unique ethnic characteristics and diagnostic challenges. Recently, the prevalence of HHA has increased in Korea, reflecting the increasing number of international marriages and increased awareness of the disease. In particular, the diagnosis of red blood cell (RBC) enzymopathy experienced a resurgence, given the advances in diagnostic techniques. In 2007, the RBC Disorder Working Party of the Korean Society of Hematology developed the Korean Standard Operating Procedure for the Diagnosis of Hereditary Hemolytic Anemia, which has been continuously updated since then. The latest Korean clinical practice guidelines for diagnosing HHA recommends performing next-generation sequencing as a preliminary step before analyzing RBC membrane proteins and enzymes. Recent breakthroughs in molecular genetic testing methods, particularly next-generation sequencing, are proving critical in identifying and providing insight into cases of HHA with previously unknown diagnoses. These innovative molecular genetic testing methods have now become important tools for the management and care planning of patients with HHA. This review aims to provide a comprehensive overview of recent advances in molecular genetic testing for the diagnosis of HHA, with particular emphasis on the Korean context.

Glucose phosphate isomerase deficiency demasked by whole-genome sequencing: a case report

BACKGROUND

Glucose-6-phosphate isomerase deficiency is a rare genetic disorder causing hereditary nonspherocytic hemolytic anemia. It is the second most common glycolytic enzymopathy in red blood cells. About 90 cases are reported worldwide, with symptoms including chronic hemolytic anemia, jaundice, splenomegaly, gallstones, cholecystitis, and in severe cases, neurological impairments, hydrops fetalis, and neonatal death.

CASE PRESENTATION

This paper details the case of the first Danish patient diagnosed with glucose-6-phosphate isomerase deficiency. The patient, a 27-year-old white female, suffered from lifelong anemia of unknown origin for decades. Diagnosis was established through whole-genome sequencing, which identified two GPI missense variants: the previously documented variant p.(Thr224Met) and a newly discovered variant p.(Tyr341Cys). The pathogenicity of these variants was verified enzymatically.

CONCLUSIONS

Whole-genome sequencing stands as a potent tool for identifying hereditary anemias, ensuring optimal management strategies.

The RoxyScan is a novel measurement of red blood cell deformability under oxidative and shear stress

Exposure to both oxidative and shear stress, a condition that the red blood cell (RBC) continuously experiences in the circulation in vivo can be mimicked in a Couette type viscometer and monitored by ektacytometry. RBCs maintain their deformation and orientation under shear stress and oxidative stress until a threshold is reached at which these conditions appear to overwhelm the elaborate and complex pathways that maintain a proper redox environment in the cell. Oxidative stress under shear alters the ability of the cell to deform, changes cell morphology, its orientation in the shear stress field, and appears to alter intracellular and membrane characteristics. The application of the RoxyScan technology allows the comparison of oxidant effects and the role of antioxidant systems. This provides the opportunity to study the ability of RBC to deal with oxidative stress in various conditions, including RBC disorders such as sickle cell disease (SCD).

Red cell abnormalities characterized by ektacytometry in children with cholestasis

BACKGROUND

Spur-cell anemia sometimes accompanies cholestasis. We postulated that even in the absence of spur-cells, cholestasis might alter red blood cell (RBC) osmotic fragility and deformability. Therefore, we assessed these RBC measures by ektacytometry in pediatric patients.

METHODS

We conducted a single center, prospective, cross-sectional investigation of RBC membrane characteristics by ektacytometry in pediatric patients with intra- and extrahepatic cholestasis followed at Cincinnati Children's Hospital Medical Center. We measured red cell membrane fragility and deformability in 17 patients with cholestasis and 17 age-matched controls without cholestasis.

RESULTS

Patients with cholestasis had decreased RBC osmotic fragility compared to controls, with a significant left shift in Omin, indicating increased RBC surface-to-volume ratio. One showed spur cell morphology. However, the other 16 had no spurring, indicating that ektacytometry is a sensitive method to detect RBC membrane abnormalities. Left shift of Omin positively correlated with serum conjugated bilirubin levels and even more negatively with serum vitamin E concentration.

CONCLUSIONS

This study suggests that subclinical red blood cell membrane abnormalities exist in most pediatric patients with cholestasis, increasing risk for hemolysis when subjected to oxidative stress. Hence minimizing pro-oxidants exposure and maximizing antioxidant exposure is advisable for this group.

CLINICALTRIALS

GOV IDENTIFIER

NCT05582447 https://clinicaltrials.gov/ct2/show/NCT05582447?cond=Cholestasis&cntry=US&state=US%3AOH&city=Cincinnati&draw=2&rank=2 .

IMPACT

Spur cell anemia due to decreased red cell osmotic fragility and decreased deformability has been reported among patients with cholestasis. Ektacytometry is a reliable, reproducible method to measure red cell osmotic fragility and deformability. Few data describe red cell osmotic fragility or deformability in patients with cholestasis who may or may not have spur cell anemia. Ektacytometry shows that red cell osmotic fragility and deformability are decreased in many children with cholestasis even when spur cell anemia has not yet occurred. Factors associated with decreased osmotic fragility include elevated serum bilirubin, elevated serum bile acids, and decreased serum vitamin E.

New erythrocyte parameters derived from the Coulter principle relate with red blood cell properties-A pilot study in diabetes mellitus

In routine hematological instruments, blood cells are counted and sized by monitoring the impedance signals induced during their passage through a Coulter orifice. However, only signals associated with centered paths in the aperture are considered for analysis, while the rejected measurements, caused by near-wall trajectories, can provide additional information on red blood cells (RBC), as recent publications suggest. To assess usefulness of two new parameters in describing alterations in RBC properties, we performed a pilot study to compare blood samples from patients with diabetes mellitus (DM), frequent pathological condition associated with impairment in RBC deformability, versus controls. A total of 345 blood samples were analyzed: 225 in the DM group and 120 in the control group. A diagram of [Formula: see text] and [Formula: see text], the two new parameters derived from the analysis of impedancemetry pulses, was used to compare distribution of RBC subpopulations between groups. To discriminate RBC from DM and control individuals, based on our multiparametric analysis, we built a score from variables derived from [Formula: see text] matrix which showed good performances: area under the receiving operating characteristic curve 0.948 (0.920-0.970), p<0.0001; best discriminating value: negative predictive value 94.7%, positive predictive value was 78.4%. These results seem promising to approach RBC alterations in routine laboratory practice. The related potential clinically relevant outcomes remain to be investigated.

Changes in Hematological and Hemorheological Parameters Following Mild COVID-19: A 4-Month Follow-Up Study

BACKGROUND

Coronavirus Disease 2019 (COVID-19) was described to affect red blood cells (RBC) in both severe and mild disease courses. The aim of this study was to investigate whether hematological and hemorheological changes that were previously described for COVID-19 patients after the acute infection state are still prominent after another 4 months to assess potential long-term effects.

METHODS

Hematological and RBC rheological parameters, including deformability and aggregation, were measured 41 days after infection in COVID-19 patients and non-COVID control (T0) and 4 months later in COVID-19 patients (T1).

RESULTS

The data confirm alterations in hematological parameters, mainly related to cell volume and hemoglobin concentration, but also reduced deformability and increased aggregation at T0 compared to control. While RBC deformability seems to have recovered, hemoglobin-related parameters and RBC aggregation were still impaired at T1. The changes were thus more pronounced in male COVID-19 patients.

CONCLUSION

COVID-19-related changes of the RBC partly consist of several months and might be related to persistent symptoms reported by many COVID-19 patients.

Influence of age and sex on osmoscan indies for next-generation osmotic gradient ektacytometry

BACKGROUND AND AIMS

Osmotic gradient ektacytometry is an important method for diagnosis of red blood cell membrane disorders. For interpretation of the osmoscan parameters on the ektacytomety, an age-matched control sample drawn at the same time is recommended for direct comparison. However, this can be challenging for laboratories to fulfil, especially when ektacytometry is performed in children. Therefore, the aim of this study was to evaluate the influence of age and sex on the osmoscan parameters.

MATERIALS AND METHODS

Blood samples from 231 subjects were analyses on a LoRRca MaxSIS. Data were investigated for need of partitioning by age and sex. After outlier detection, reference intervals (RIs) for osmoscan parameters were estimated.

RESULTS

For all parameters except EImin, lower values were observed in infants < 3 month (N = 50) than in all other age group. Hence, RIs were calculated separately for this age group. For EImin, a unified RI was calculated. No difference between sexes was observed for any of the parameters.

CONCLUSION

Lower RIs and a left shift in the osmoscan curves were observed in infants < 3 months compared with older subjects. Hence, age-matched controls are necessary when evaluating ektacytometry in newborns, but can be ignored in older children and adults. This will ease the laboratory workflow when performing ektacytometry.

Quality assessment of red blood cell concentrates from blood donors at the extremes of the age spectrum: The BEST collaborative study

BACKGROUND

Blood donors at the extremes of the age spectrum (16-19 years vs. ≥75 years) are characterized by increased risks of iron deficiency and anemia, and are often underrepresented in studies evaluating the effects of donor characteristics on red blood cells (RBC) transfusion effectiveness. The aim of this study was to conduct quality assessments of RBC concentrates from these unique age groups.

STUDY DESIGN

We characterized 150 leukocyte-reduced (LR)-RBCs units from 75 teenage donors, who were matched by sex, and ethnicity with 75 older donors. LR-RBC units were manufactured at three large blood collection centers in the USA and Canada. Quality assessments included storage hemolysis, osmotic hemolysis, oxidative hemolysis, osmotic gradient ektacytometry, hematological indices, and RBC bioactivity.

RESULTS

RBC concentrates from teenage donors had smaller (9%) mean corpuscular volume and higher (5%) RBC concentration compared with older donors counterparts. Stored RBCs from teenage donors exhibited increased susceptibility to oxidative hemolysis (>2-fold) compared with RBCs from older donors. This was observed at all testing centers independent of sex, storage duration, or the type of additive solution. RBCs from teenage male donors had increased cytoplasmatic viscosity and lower hydration compared with older donor RBCs. Evaluations of RBC supernatant bioactivity suggested that donor age was not associated with altered expression of inflammatory markers (CD31, CD54, and IL-6) on endothelial cells.

CONCLUSIONS

The reported findings are likely intrinsic to RBCs and reflect age-specific changes in RBC antioxidant capacity and physical characteristics that may impact RBC survival during cold storage and after transfusion.

Targeted next-generation sequencing identifies novel deleterious variants in ANK1 gene causing severe hereditary spherocytosis in Indian patients: expanding the molecular and clinical spectrum

Hereditary Spherocytosis (HS) is a common cause of hemolytic anemia varying from mild to severe hemolysis due to defects in red cell membrane protein genes, namely ANK1, SPTB, SPTA1, SLC4A1, and EPB42. These genes are considerably very large spaning 40-50 exons making gene-by-gene analysis costly and laborious by conventional methods. In this study, we explored 26 HS patients harboring 21 ANK1 variants identified by next-generation sequencing (NGS), characteristics and spectrum of the detected ANK1variants were analyzed in this study. Clinically, all the HS patients showed moderate to severe transfusion-dependent hemolytic anemia, some requiring splenectomy. We identified 13 novel and 8 reported variants, mainly 9 frameshifts, 2 missense, 6 nonsense, and 4 splice site ANK1 variants, using NGS technology. Frameshifts were remarkably the most common variant type seen in Indian HS patients with ANK1 gene defects. We have also explored expression levels of red cell membrane ankyrin protein by flow cytometry in 14 HS patients with ANK1 gene defects and a significant reduction in ankyrin protein expression has been found. This report mainly illustrates the molecular and phenotypic heterogeneity of ANK1 variants causing HS in Indian patients. Ankyrin-1 mutations are a significant cause of loss of function in dominant HS in the Indian population. Comprehensive genetic and phenotypic evaluation assists in implementing the knowledge of genetic patterns and spectrum of ANK1 gene variants, providing molecular support for HS diagnosis.

Case report: Transfusion independence and abolition of extravascular hemolysis in a PNH patient treated with pegcetacoplan

More than half of patients with paroxysmal nocturnal hemoglobinuria (PNH) treated with complement fraction C5 inhibitors experience residual anemia and hemolysis. This is partly due to the persistent activation of the complement cascade upstream C5, resulting in C3 deposition on PNH erythrocytes and extravascular hemolysis in the reticuloendothelial system. Pegcetacoplan is the first proximal C3 inhibitor to be approved for PNH basing on favorable efficacy and safety data in both naïve and eculizumab treated PNH. Here we report the first Italian patient treated with pegcetacoplan in a named patient program. The patient suffered from hemolytic PNH associated with CALR+ myeloproliferative neoplasm and was heavily transfusion dependent despite eculizumab therapy. Treatment with pegcetacoplan induced a dramatic improvement in Hb, along with normalization of unconjugated bilirubin and reticulocytes, as markers of extravascular hemolysis. Sequential laboratory workup showed the disappearance of C3 deposition on erythrocytes by direct anti-globulin test, the increase of PNH clone on erythrocytes, and a peculiar right shift of the ektacytometry curve. The drug was well tolerated, and the patient reported a significant improvement in his quality of life. Overall, pegcetacoplan appears a safe and effective option "ready to use" in the clinic for patients with PNH and suboptimal response to anti-C5 agents.

Effect of primary lesions in cytoskeleton proteins on red cell membrane stability in patients with hereditary spherocytosis

We investigated by targeted next generation sequencing the genetic bases of hereditary spherocytosis in 25 patients and compared the molecular results with the biochemical lesion of RBC membrane obtained by SDS-PAGE analysis. The HS diagnosis was based on available guidelines for diagnosis of congenital hemolytic anemia, and patients were selected because of atypical clinical presentation or intra-family variability, or because presented discrepancies between laboratory investigation and biochemical findings. In all patients but 5 we identified pathogenic variants in SPTA1, SPTB, ANK1, SLC4A1, EPB42 genes able to justify the clinical phenotype. Interestingly, a correspondence between the biochemical lesion and the molecular defect was identified in only 11/25 cases, mostly with band 3 deficiency due to SLC4A1 mutations. Most of the mutations in SPTB and ANK1 gene didn’t hesitate in abnormalities of RBC membrane protein; conversely, in two cases the molecular lesion didn’t correspond to the biochemical defect, suggesting that a mutation in a specific cytoskeleton protein may result in a more complex RBC membrane damage or suffering. Finally, in two cases the HS diagnosis was maintained despite absence of both protein defect and molecular lesion, basing on clinical and family history, and on presence of clear laboratory markers of HS. The study revealed complex relationships between the primary molecular lesion and the final effect in the RBC membrane cytoskeleton, and further underlines the concept that there is not a unique approach to the diagnosis of HS.

Unravelling the genetic and phenotypic heterogeneity of SPTA1 gene variants in Hereditary Elliptocytosis and Hereditary Pyropoikilocytosis patients using next-generation sequencing

Hereditary Elliptocytosis (HE) and Hereditary Pyropoikilocytosis (HPP) are clinically and genetically heterogeneous red cell membranopathies that result from the defects in the horizontal linkage between RBC (red blood cell) membrane and cytoskeletal proteins affecting its mechanical stability and deformability thereby reducing its lifespan. The principal defect in HE and HPP is due to dysfunction or deficiency of RBC cytoskeletal proteins namely, α-spectrin (SPTA1), β-spectrin (SPTB) and protein 4.1R (EPB41R). This study reports the genetic and phenotypic heterogeneity of 10 Indian patients (5 with HE and 5 with HPP)harboringSPTA1 gene variants. We used targeted next-generation sequencing (t-NGS) to characterize the causative genetic variants in 10 HE/HPP suspected patients and studied the correlation between the identified variants with their corresponding phenotypic features.t-NGS detected 12 SPTA1 variants, out of which 8 are novel. Nearly all of the detected variants have a damaging effect on the protein stability and function, as shown by the insilico analysis. The possible effect of the detected variants on the protein structure was studied using the HOPE software and DynaMut tools wherever possible. To the best of our knowledge, this is the first report on HE/HPP cases confirmed by a genetic study from India. To conclude, HE is caused by monoallelic mutations while HPP, the more severe form, is typically caused by biallelic (homozygous or compound heterozygous) mutations justifying the phenotypic heterogeneity associated with patients. Moreover, analysis at the molecular level by NGS permits diagnosis in these disorders with highly variable heterogeneity requiring regular transfusions and may facilitate prognostic contemplations.

Interspecies Diversity of Osmotic Gradient Deformability of Red Blood Cells in Human and Seven Vertebrate Animal Species

Plasma and blood osmolality values show interspecies differences and are strictly regulated. The effect of these factors also has an influence on microrheological parameters, such as red blood cell (RBC) deformability and aggregation. However, little is known about the interspecies differences in RBC deformability at various blood osmolality levels (osmotic gradient RBC deformability). Our aim was to conduct a descriptive–comparative study on RBC osmotic gradient deformability in several vertebrate species and human blood. Blood samples were taken from healthy volunteers, dogs, cats, pigs, sheep, rabbits, rats, and mice, to measure hematological parameters, as well as conventional and osmotic gradient RBC deformability. Analyzing the elongation index (EI)–osmolality curves, we found the highest maximal EI values (EI max) in human, dog, and rabbit samples. The lowest EI max values were seen in sheep and cat samples, in addition to a characteristic leftward shift of the elongation index–osmolality curves. We found significant differences in the hyperosmolar region. A correlation of mean corpuscular volume and mean corpuscular hemoglobin concentration with osmoscan parameters was found. Osmotic gradient deformability provides further information for better exploration of microrheological diversity between species and may help to better understand the alterations caused by osmolality changes in various disorders.

Even patients with mild COVID-19 symptoms after SARS-CoV-2 infection show prolonged altered red blood cell morphology and rheological parameters

Infection with the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and the associated coronavirus disease-19 (COVID-19) might affect red blood cells (RBC); possibly altering oxygen supply. However, investigations of cell morphology and RBC rheological parameters during a mild disease course are lacking and thus, the aim of the study. Fifty individuals with mild COVID-19 disease process were tested after the acute phase of SARS-CoV-2 infection (37males/13 females), and the data were compared to n = 42 healthy controls (30 males/12 females). Analysis of venous blood samples, taken at rest, revealed a higher percentage of permanently elongated RBC and membrane extensions in COVID-19 patients. Haematological parameters and haemoglobin concentration, MCH and MCV in particular, were highly altered in COVID-19. RBC deformability and deformability under an osmotic gradient were significantly reduced in COVID-19 patients. Higher RBC-NOS activation was not capable to at least in part counteract these reductions. Impaired RBC deformability might also be related to morphological changes and/or increased oxidative state. RBC aggregation index remained unaffected. However, higher shear rates were necessary to balance the aggregation-disaggregation in COVID-19 patients which might be, among others, related to morphological changes. The data suggest prolonged modifications of the RBC system even during a mild COVID-19 disease course.

Red Blood Cell Morphodynamics in Patients with Polycythemia Vera and Stroke

Polycythemia vera (PV) is a Ph-negative myeloproliferative neoplasm (MPN) which is characterized by erythrocytosis and a high incidence of thrombotic complications, including stroke. The study aimed to evaluate red blood cell (RBC) morphodynamic properties in PV patients and their possible association with stroke. We enrolled 48 patients with PV in this cross-sectional study, 13 of which have a history of ischemic stroke. The control group consisted of 90 healthy subjects. RBC deformability and aggregation analysis were performed using a laser-assisted optical rotational red cell analyzer. The following parameters were calculated: aggregation amplitude (Amp), RBC rouleaux formation time constant (Tf), time of formation of three-dimensional aggregates (Ts), aggregation index (AI), rate of complete disaggregation (y-dis), and the maximal elongation of RBC (EImax). Statistical analysis was performed with the R programming language. There were significant differences in RBCs morphodynamics features between patients with PV and the control group. Lower EImax (0.47 (0.44; 0.51) vs. 0.51 (0.47; 0.54), p < 0.001) and γ-dis (100 (100; 140) vs. 140 (106; 188) s⁻¹, p < 0.001) along with higher amplitude (10.1 (8.6; 12.2) vs. 7.7 (6.6; 9.2), p < 0.001) was seen in patients with PV compared with control. A statistically significant difference between PV patients with and without stroke in aggregation amplitude was found (p = 0.03). A logistic regression model for stroke was built based on RBC morphodynamics which performed reasonably well (p = 0.01). RBC alterations may be associated with overt cerebrovascular disease in PV, suggesting a possible link between erythrocyte morphodynamics and increased risk of stroke.

Influence of diabetes and hypercholesterolemia on laboratory methods for hereditary spherocytosis diagnosis

INTRODUCTION

Hereditary spherocytosis (HS) is characterized by decreased erythrocyte deformability resulting in hemolytic anemia. This is a heterogeneous disease regarding underlying protein deficiency, disease severity, age at diagnosis and clinical course. Although largely considered as pediatric disease, HS could be initially diagnosed also in elder patients as a result of gallstones or splenomegaly fortuitous finding. Concurrently, common adulthood metabolic disorders like diabetes or dyslipidemia are also known to impair RBC rheology and deformability. Therefore, we aimed to investigate if these diseases affect the screening and diagnostic tools used for HS diagnosis.

METHODS

We applied our workflow for HS diagnosis on 95 pathological samples: 29 patients with diabetes, 20 with hypercholesterolemia, 17 with dyslipidemia, 6 with hypertriglyceridemia, 23 with metabolic syndrome (MS). Thus, a total of 73 samples were analyzed by automated reticulocyte analysis, 52 by cryohemolysis test, and 41 by ektacytometry osmoscan analysis as we used two out of the three tests for each individual sample.

RESULTS

Applying our screening algorithm based on automated reticulocyte indices, a total of 4 samples (4.2%): one sample (5%) from the diabetes group and three samples (16.7%) from the MS group, positioned into the HS zone. However, no significant difference was found between any of the pathological groups and the controls for the cryohemolysis test or the osmoscan.

CONCLUSION

While diabetes and hypercholesterolemia are pathologic conditions known to present with decreased erythrocyte deformability and disturbed rheology, their possible concomitant presence with HS would not interfere with the screening and confirmatory laboratory methods.

Facilitating EMA binding test performance using fluorescent beads combined with next‐generation sequencing

The eosin‐5′‐maleimide (EMA) binding test is widely used as diagnostic test for hereditary spherocytosis (HS), one of the most common haemolytic disorders in Caucasian populations. We recently described the advantages of replacing the use of healthy control blood samples with fluorescent beads in a modified EMA binding assay. In this study we further explore this novel approach. We performed targeted next‐generation sequencing, modified EMA binding test and osmotic gradient ektacytometry on consecutive individuals referred to our laboratory on the suspicion of HS. In total, 33 of 95 carried a (likely) pathogenic variant, and 24 had variants of uncertain significance (VUS). We identified a total 79 different (likely) pathogenic variants and VUS, including 43 novel mutations. Discarding VUS and recessive mutations in STPA1, we used the occurrence of (likely) pathogenic variants to generate a diagnostic threshold for our modified EMA binding test. Twenty‐one of 23 individuals with non‐SPTA1 (likely) pathogenic variants had EMA ≥ 43.6 AU, which was the optimal threshold in receiver operating characteristic (ROC) analysis. Accuracy was excellent at 93.4% and close to that of osmotic gradient ektacytometry (98.7%). In conclusion, we were able to simplify the EMA‐binding test by using rainbow beads as reference and (likely) pathogenic variants to define an accurate cut‐off value.

Confounding factors in the diagnosis and clinical course of rare congenital hemolytic anemias

Congenital hemolytic anemias (CHAs) comprise defects of the erythrocyte membrane proteins and of red blood cell enzymes metabolism, along with alterations of erythropoiesis. These rare and heterogeneous conditions may generate several difficulties from the diagnostic point of view. Membrane defects include hereditary spherocytosis and elliptocytosis, and the group of hereditary stomatocytosis; glucose-6-phosphate dehydrogenase and pyruvate kinase, are the most common enzyme deficiencies. Among ultra-rare forms, it is worth reminding other enzyme defects (glucosephosphate isomerase, phosphofructokinase, adenylate kinase, triosephosphate isomerase, phosphoglycerate kinase, hexokinase, and pyrimidine 5′-nucleotidase), and congenital dyserythropoietic anemias. Family history, clinical findings (anemia, hemolysis, splenomegaly, gallstones, and iron overload), red cells morphology, and biochemical tests are well recognized diagnostic tools. Molecular findings are increasingly used, particularly in recessive and de novo cases, and may be fundamental in unraveling the diagnosis. Notably, several confounders may further challenge the diagnostic workup, including concomitant blood loss, nutrients deficiency, alterations of hemolytic markers due to other causes (alloimmunization, infectious agents, rare metabolic disorders), coexistence of other hemolytic disorders (autoimmune hemolytic anemia, paroxysmal nocturnal hemoglobinuria, etc.). Additional factors to be considered are the possible association with bone marrow, renal or hepatic diseases, other causes of iron overload (hereditary hemochromatosis, hemoglobinopathies, metabolic diseases), and the presence of extra-hematological signs/symptoms. In this review we provide some instructive clinical vignettes that highlight the difficulties and confounders encountered in the diagnosis and clinical management of CHAs.

[Consensus document for the diagnosis and treatment of pyruvate kinase deficiency]

Pyruvate kinase (PK) deficiency is the second most frequent enzymopathy and the most common cause of chronic hereditary non-spherocytic haemolytic anaemia. Its global prevalence is underestimated due to low clinical suspicion of mild cases, associated with difficulties in the performance and interpretation of PK enzymatic activity assays. With the advent of next generation sequencing techniques, a better diagnostic approach is achieved. Treatment remains based on red blood cell transfusions and splenectomy, with special attention to iron overload, not only in transfusion-dependent patients. Nowadays, allogeneic hematopoietic stem cell transplantation is the only curative treatment, recommended only in selected cases of severely affected patients with an HLA-identical donor. Novel pharmacological and gene therapies are in clinical trials, with promising results. In this article, the Spanish Erythropathology Group reviews the current situation of PK deficiency, paying special attention to the usefulness of different diagnostic techniques and to actual and emerging treatments.

Severe Presentation of Congenital Hemolytic Anemias in the Neonatal Age: Diagnostic and Therapeutic Issues

Congenital hemolytic anemias (CHAs) are a group of diseases characterized by premature destruction of erythrocytes as a consequence of intrinsic red blood cells abnormalities. Suggestive features of CHAs are anemia and hemolysis, with high reticulocyte count, unconjugated hyperbilirubinemia, increased lactate dehydrogenase (LDH), and reduced haptoglobin. The peripheral blood smear can help the differential diagnosis. In this review, we discuss the clinical management of severe CHAs presenting early on in the neonatal period. Appropriate knowledge and a high index of suspicion are crucial for a timely differential diagnosis and management. Here, we provide an overview of the most common conditions, such as glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency, and hereditary spherocytosis. Although rare, congenital dyserythropoietic anemias are included as they may be suspected in early life, while hemoglobinopathies will not be discussed, as they usually manifest at a later age, when fetal hemoglobin (HbF) is replaced by the adult form (HbA).

Targeted Next Generation Sequencing and Diagnosis of Congenital Hemolytic Anemias: A Three Years Experience Monocentric Study

Congenital hemolytic anemias (CHAs) are heterogeneous and rare disorders caused by alterations in structure, membrane transport, metabolism, or red blood cell production. The pathophysiology of these diseases, in particular the rarest, is often poorly understood, and easy-to-apply tools for diagnosis, clinical management, and patient stratification are still lacking. We report the 3-years monocentric experience with a 43 genes targeted Next Generation Sequencing (t-NGS) panel in diagnosis of CHAs; 122 patients from 105 unrelated families were investigated and the results compared with conventional laboratory pathway. Patients were divided in two groups: 1) cases diagnosed with hematologic investigations to be confirmed at molecular level, and 2) patients with unexplained anemia after extensive hematologic investigation. The overall sensitivity of t-NGS was 74 and 35% for families of groups 1 and 2, respectively. Inside this cohort of patients we identified 26 new pathogenic variants confirmed by functional evidence. The implementation of laboratory work-up with t-NGS increased the number of diagnoses in cases with unexplained anemia; cytoskeleton defects are well detected by conventional tools, deserving t-NGS to atypical cases; the diagnosis of Gardos channelopathy, some enzyme deficiencies, familial siterosterolemia, X-linked defects in females and other rare and ultra-rare diseases definitely benefits of t-NGS approaches.

Gardos channelopathy: functional analysis of a novel KCNN4 variant

We show that the novel KCNN4 variant p.S314P is a gain-of-function mutation but is less severe than the previously reported p.R352H variant. The clinical heterogeneity, blurred symptoms, and absence of specific diagnostic markers make the diagnosis of Gardos channelopathy challenging.

Ektacytometry Analysis of Post-splenectomy Red Blood Cell Properties Identifies Cell Membrane Stability Test as a Novel Biomarker of Membrane Health in Hereditary Spherocytosis

Hereditary spherocytosis (HS) is the most common form of hereditary chronic hemolytic anemia. It is caused by mutations in red blood cell (RBC) membrane and cytoskeletal proteins, which compromise membrane integrity, leading to vesiculation. Eventually, this leads to entrapment of poorly deformable spherocytes in the spleen. Splenectomy is a procedure often performed in HS. The clinical benefit results from removing the primary site of destruction, thereby improving RBC survival. But whether changes in RBC properties contribute to the clinical benefit of splenectomy is unknown. In this study we used ektacytometry to investigate the longitudinal effects of splenectomy on RBC properties in five well-characterized HS patients at four different time points and in a case-control cohort of 26 HS patients. Osmotic gradient ektacytometry showed that splenectomy resulted in improved intracellular viscosity (hydration state) whereas total surface area and surface-to-volume ratio remained essentially unchanged. The cell membrane stability test (CMST), which assesses the in vitro response to shear stress, showed that after splenectomy, HS RBCs had partly regained the ability to shed membrane, a property of healthy RBCs, which was confirmed in the case-control cohort. In particular the CMST holds promise as a novel biomarker in HS that reflects RBC membrane health and may be used to asses treatment response in HS.

Red cell membrane disorders: structure meets function

The mature red blood cell (RBC) lacks a nucleus and organelles characteristic of most cells, but it is elegantly structured to perform the essential function of delivering oxygen and removing carbon dioxide from all other cells while enduring the shear stress imposed by navigating small vessels and sinusoids. Over the past several decades, the efforts of biochemists, cell and molecular biologists, and hematologists have provided an appreciation of the complexity of RBC membrane structure, while studies of the RBC membrane disorders have offered valuable insights into structure-function relationships. Within the last decade, advances in genetic testing and its increased availability have made it possible to substantially build upon this foundational knowledge. Although disorders of the RBC membrane due to altered structural organization or altered transport function are heterogeneous, they often present with common clinical findings of hemolytic anemia. However, they may require substantially different management depending on the underlying pathophysiology. Accurate diagnosis is essential to avoid emergence of complications or inappropriate interventions. We propose an algorithm for laboratory evaluation of patients presenting with symptoms and signs of hemolytic anemia with a focus on RBC membrane disorders. Here, we review the genotypic and phenotypic variability of the RBC membrane disorders in order to raise the index of suspicion and highlight the need for correct and timely diagnosis.

Congenital dyserythropoietic anemias

Congenital dyserythropoietic anemias (CDAs) are a heterogeneous group of inherited anemias that affect the normal differentiation-proliferation pathways of the erythroid lineage. They belong to the wide group of ineffective erythropoiesis conditions that mainly result in monolinear cytopenia. CDAs are classified into the 3 major types (I, II, III), plus the transcription factor-related CDAs, and the CDA variants, on the basis of the distinctive morphological, clinical, and genetic features. Next-generation sequencing has revolutionized the field of diagnosis of and research into CDAs, with reduced time to diagnosis, and ameliorated differential diagnosis in terms of identification of new causative/modifier genes and polygenic conditions. The main improvements regarding CDAs have been in the study of iron metabolism in CDAII. The erythroblast-derived hormone erythroferrone specifically inhibits hepcidin production, and its role in the mediation of hepatic iron overload has been dissected out. We discuss here the most recent advances in this field regarding the molecular genetics and pathogenic mechanisms of CDAs, through an analysis of the clinical and molecular classifications, and the complications and clinical management of patients. We summarize also the main cellular and animal models developed to date and the possible future therapies.

Donor Age and Red Cell Age Contribute to the Variance in Lorrca Indices in Healthy Donors for Next Generation Ektacytometry: A Pilot Study

The ability of red blood cells (RBCs) to transport gases, their lifespan as well as their rheological properties invariably depend on the deformability, hydration, and membrane stability of these cells, which can be measured by Laser optical rotational red cell analyser (Lorrca® Maxsis, RR Mechatronics). The osmoscan mode of Lorrca is currently used in diagnosis of rare anemias in clinical laboratories. However, a broad range of normal values for healthy subjects reduces the sensitivity of this method for diagnosis of mild disease phenotype. In this pilot study, we explored the impact of age and gender of 45 healthy donors, as well as RBC age on the Lorrca indices. Whereas gender did not affect the Lorrca indices in our study, the age donors had a profound effect on the O_hyper parameter. To study the impact of RBC age on the osmoscan parameters, we have isolated low (L)-, medium (M)-, or high (H)- density fractions enriched with young, mature, and senescent RBCs, respectively, and evaluated the influence of RBC age-related properties, such as density, morphology, and redox state, on the osmoscan indices. As before, O_hyper was the most sensitive parameter, dropping markedly with an increase in RBC density and age. Senescence was associated with a decrease in deformability (EI_max) and tolerability to low and high osmolatites (Area). L-fraction was enriched with reticulocytes and cells with high projected area and EMA staining, but also contained a small number of cells small in projected area and most likely, terminally senescent. L-fraction was on average slightly less deformable than mature cells. The cells from the L-fraction produced more oxidants and NO than all other fractions. However, RBCs from the L-fraction contained maximal levels of reduced thiols compared to other fractions. Our study suggests that reference values for O_hyper should be age-stratified, and, most probably, corrected for the average RBC age. Further multi-center study is required to validate these suggestions before implementing them into clinical practice.

Screening tools for hereditary hemolytic anemia: new concepts and strategies

INTRODUCTION

Hereditary hemolytic anemias are a group of rare and heterogeneous disorders due to abnormalities in structure, metabolism, and transport functions of erythrocytes; they may overlap in clinical and hematological features making differential diagnosis difficult, particularly in mild and atypical forms.

AREAS COVERED

In the present review, the main tools currently adopted in routine hematologic investigation for the diagnosis of hereditary hemolytic anemias are described, together with the new diagnostic approaches that are being to be developed in the next future. Available recommendations in this field together with a systematic review through MEDLINE, EMBASE, and PubMED for publications in English from 2000 to 2020 in regards to diagnostic aspects of hereditary hemolytic anemias have been considered.

EXPERT OPINION

The recent development of specific molecules and treatments for hereditary hemolytic anemias and the increased interest in translational research raised the attention on differential diagnosis and the demand for novel diagnostic assays and devices. Automatic blood cell analyzers, omic-approaches including NGS technologies, and development of new automated tools based on artificial neural networks definitely represent the future strategies in this field.

AG-348 (Mitapivat), an allosteric activator of red blood cell pyruvate kinase, increases enzymatic activity, protein stability, and ATP levels over a broad range of PKLR genotypes

Pyruvate kinase (PK) deficiency is a rare hereditary disorder affecting red blood cell (RBC) glycolysis, causing changes in metabolism including a deficiency in adenosine triphosphate (ATP). This affects red cell homeostasis, promoting premature removal of RBC from the circulation. In this study, we characterized and evaluated the effect of AG-348, an allosteric activator of PK that is currently in clinical trials for treatment of PK deficiency, on RBC and erythroid precursors from PK-deficient patients. In 15 patients, ex vivo treatment with AG-348 resulted in increased enzymatic activity in all patients' cells after 24 hours (h) (mean increase: 1.8-fold; range: 1.2-3.4). ATP levels increased (mean increase: 1.5-fold; range: 1.0-2.2) similar to control cells (mean increase: 1.6-fold; range: 1.4-1.8). Generally, PK thermostability was strongly reduced in PK-deficient RBC. Ex vivo treatment with AG-348 increased residual activity from 1.4- to >10-fold more than residual activity of vehicle-treated samples. Protein analyses suggest that a sufficient level of PK protein is required for cells to respond to AG- 348 treatment ex vivo, as treatment effects were minimal in patient cells with very low or undetectable levels of PK-R. In half of the patients, ex vivo treatment with AG-348 was associated with an increase in RBC deformability. These data support the hypothesis that drug intervention with AG- 348 effectively up-regulates PK enzymatic activity and increases stability in PK-deficient RBC over a broad range of PKLR genotypes. The concomitant increase in ATP levels suggests that glycolytic pathway activity may be restored. AG-348 treatment may represent an attractive way to correct the underlying pathologies of PK deficiency. (AG-348 is currently in clinical trials for the treatment of PK deficiency. Registered at clinicaltrials.gov identifiers: NCT02476916, NCT03853798, NCT03548220, NCT03559699).

Genetics and Genomics Approaches for Diagnosis and Research Into Hereditary Anemias

The hereditary anemias are a relatively heterogeneous set of disorders that can show wide clinical and genetic heterogeneity, which often hampers correct clinical diagnosis. The classical diagnostic workflow for these conditions generally used to start with analysis of the family and personal histories, followed by biochemical and morphological evaluations, and ending with genetic testing. However, the diagnostic framework has changed more recently, and genetic testing is now a suitable approach for differential diagnosis of these patients. There are several approaches to this genetic testing, the choice of which depends on phenotyping, genetic heterogeneity, and gene size. For patients who show complete phenotyping, single-gene testing remains recommended. However, genetic analysis now includes next-generation sequencing, which is generally based on custom-designed targeting panels and whole-exome sequencing. The use of next-generation sequencing also allows the identification of new causative genes, and of polygenic conditions and genetic factors that modify disease severity of hereditary anemias. In the research field, whole-genome sequencing is useful for the identification of non-coding causative mutations, which might account for the disruption of transcriptional factor occupancy sites and cis-regulatory elements. Moreover, advances in high-throughput sequencing techniques have now resulted in the identification of genome-wide profiling of the chromatin structures known as the topologically associating domains. These represent a recurrent disease mechanism that exposes genes to inappropriate regulatory elements, causing errors in gene expression. This review focuses on the challenges of diagnosis and research into hereditary anemias, with indications of both the advantages and disadvantages. Finally, we consider the future perspectives for the use of next-generation sequencing technologies in this era of precision medicine.

Artificial intelligence meets hematology

The application of artificial intelligence (AI) in hematology it not new at all. However, it increasingly becomes part of the measurement of hematological parameters and subsequently also influences decision making. Here some examples are provided where well established parameters could be exploited better, if data are not reduced to single values but instead the entire data generation process is considered. Furthermore applications of artificial neural networks (ANN), point of care (PoC) devices and the internet of things (IoT) are discussed. Beside all the technical advancements human judgement will remain the last decision.

How I approach hereditary hemolytic anemia and splenectomy

Hereditary hemolytic anemias (HHA) are a heterogeneous group of anemias associated with decreased red cell survival. While there can be clinical benefit of splenectomy in many cases, splenectomy is not appropriate for all types of HHA. Additionally, there are significant risks during and following splenectomy including surgical risks, postsplenectomy sepsis, and thrombotic complications. This review discusses the diagnostic approach to HHA as well as the role of splenectomy in the management. Surgical approaches and outcomes for total and partial splenectomy are discussed.

Characterization of hereditary red blood cell membranopathies using combined targeted next-generation sequencing and osmotic gradient ektacytometry

Hereditary red blood cell (RBC) membranopathies are characterized by mutations in genes encoding skeletal proteins that alter the membrane complex structure. Hereditary spherocytosis (HS) is the most common inherited RBC membranopathy leading to hereditary hemolytic anemia with a worldwide distribution and an estimated prevalence, in Europe, of about 1:2000 individuals. The recent availability of targeted next generation sequencing (t-NGS) and its combination with RBC deformability measured with a laser-assisted optical rotational ektacytometer (LoRRca) has demonstrated to be the most powerful contribution to lower the percentage of hereditary hemolytic anemia undiagnosed cases. In order to know the kind and frequency of RBC membrane mutations in our geographical area (Catalonia) and to better understand their pathophysiology, 42 unrelated, non-transfusion-dependent (NTD) patients with hereditary hemolytic anemia have been studied by combining t-NGS and LoRRca. The osmoscan module of LoRRca provides three rheological profiles that reflect the maximal deformability (EImax), osmotic fragility (Omin), and hydration state (Ohyper) of RBCs and contribute to a better understanding of the contribution RBC rheology to the severity of anemia. From the 42 patients studied, 37 were suspected to be a RBC membrane defect due to phenotypic characteristics and abnormal RBC morphology and, from these, in 31 patients (83.8% of cases) the mutation was identified by t-NGS. No definite diagnosis was achieved in 11 patients (26.2% of cases), including 6 out of 37 cases, with suspected membranopathy, and 5 with unclassifiable HHA. In all these undiagnosed patients, the existence of hemoglobinopathy and/or enzymopathy was ruled out by conventional methods.

Erythrocyte deformability reduction in various pediatric hematologic diseases

BACKGROUND

Previously, hemorheology studies using Rheoscan mainly focused on chronic kidney disease, cardiovascular disease, and endocrine disease in adults. The study using LORCA focused on erythrocyte disease. There were no studies using Rheoscan in children.

OBJECTIVE

We aimed to investigate erythrocyte deformability among various hematologic diseases occurring in children, namely, iron deficiency anemia (IDA), hereditary spherocytosis (HS), immune thrombocytopenia (ITP), and aplastic anemia (AA).

METHODS

Differences between those with HS, IDA, ITP, AA and healthy controls were compared among 43 patients, comprising 7 patients with HS, 8 patients with IDA, 6 patients with AA, 9 patients with ITP, and 13 healthy controls. Erythrocyte deformability was measured using a microfluidic ektacytometer (RheoScan-D, RheoMeditech, Seoul, Korea). The erythrocyte elongation index (EI) was defined as (L - W)/(L + W), where L and W are the major and minor axes of the ellipse, respectively.

RESULTS

The EI values of IDA, HS and AA were significantly decreased compared with healthy controls, but those of ITP were similar to healthy controls.

CONCLUSIONS

This study showed that erythrocyte deformability differed among various hematologic diseases. Further study concerning correlation in relation to the diagnostic and prognostic significance of erythrocyte deformability in hematologic disease is needed.

Mechanical Signature of Red Blood Cells Flowing Out of a Microfluidic Constriction Is Impacted by Membrane Elasticity, Cell Surface-to-Volume Ratio and Diseases

Despite the fact that Red Blood Cells (RBCs) have been intensively studied in the past 50 years to characterize mechanical phenotypes associated with both healthy and pathological states, only ektacytometry (i.e., laser diffractometry) is currently used by hematologists to screen for RBC membrane disorders. Therefore, the development of new diagnostic tools able to perform analysis at the scale of a single cell, over a statistically relevant population, would provide important complementary information. But these new diagnostic tools would have to be able to discriminate between different disorders causing a change in RBCs mechanical properties. We evaluated the mechanical response of artificially rigidified RBCs flowing through a microfluidic constriction. The geometry consists in a 50 μm wide channel with a succession of 14 tooth-like patterns, each composed of a 5 μm wide and 10 μm long constriction, associated with a 25 μm wide and 10 μm long enlargement. RBCs deformability was altered using two chemical treatments, known to affect RBCs membrane surface area and membrane deformability, lysolecithine (LPC) and diamide, respectively. Differences between samples were highlighted by the representation of the inverse of the shape recovery time (1/τ r ), versus the extension at the exit of the constriction, D out . The results demonstrate that our approach is able to provide a direct signature of RBCs membrane composition and architecture, as it allows discriminating the effect of changes in RBCs membrane surface area from changes in RBCs membrane deformability. Finally, in order to evaluate the potential of our microsystem to detect pathological cells, we have performed preliminary experiments on patients with Hereditary Spherocytosis (HS) or Sickle Cell Anemia (SCA).

Trends in the Development of Diagnostic Tools for Red Blood Cell-Related Diseases and Anemias

In the recent years, the progress in genetic analysis and next-generation sequencing technologies have opened up exciting landscapes for diagnosis and study of molecular mechanisms, allowing the determination of a particular mutation for individual patients suffering from hereditary red blood cell-related diseases or anemia. However, the huge amount of data obtained makes the interpretation of the results and the identification of the pathogenetic variant responsible for the diseases sometime difficult. Moreover, there is increasing evidence that the same mutation can result in varying cellular properties and different symptoms of the disease. Even for the same patient, the phenotypic expression of the disorder can change over time. Therefore, on top of genetic analysis, there is a further request for functional tests that allow to confirm the pathogenicity of a molecular variant, possibly to predict prognosis and complications (e.g., vaso-occlusive pain crises or other thrombotic events) and, in the best case, to enable personalized theranostics (drug and/or dose) according to the disease state and progression. The mini-review will reflect recent and future directions in the development of diagnostic tools for red blood cell-related diseases and anemias. This includes point of care devices, new incarnations of well-known principles addressing physico-chemical properties, and interactions of red blood cells as well as high-tech screening equipment and mobile laboratories.

Simple Syntheses of New Pegylated Trehalose Derivatives as a Chemical Tool for Potential Evaluation of Cryoprotectant Effects on Cell Membrane

In our work, we developed the synthesis of new polyfunctional pegylated trehalose derivatives and evaluated their cryoprotective effect using flow cytometry. We showed that new compounds (modified trehaloses) bound to appropriate extracellular polymeric cryoprotectants could be helpful as a chemical tool for the evaluation of their potential toxic cell membrane influences. Our aim was to form a chemical tool for the evaluation of cryoprotectant cell membrane influences, which are still not easily predicted during the freezing/thawing process. We combined two basic cryoprotectants: polyethyleneglycols (PEGs) and trehalose in the new chemical compounds—pegylated trehalose hybrids. If PEG and trehalose are chemically bound and trehalose is adsorbed on the cell surface PEGs molecules which are, due to the chemical bonding with trehalose, close to the cell surface, can remove the cell surface hydration layer which destabilizes the cell membrane. This was confirmed by the comparison of new material, PEG, trehalose, and their mixture cryoprotective capabilities.

The Complexity of Genotype-Phenotype Correlations in Hereditary Spherocytosis: A Cohort of 95 Patients: Genotype-Phenotype Correlation in Hereditary Spherocytosis

Hereditary spherocytosis (HS) is a phenotypically and genetically heterogeneous disease. With the increased use of Next Generation Sequencing (NGS) techniques in the diagnosis of red blood cell disorders, the list of unique pathogenic mutations underlying HS is growing rapidly. In this study, we aimed to explore genotype-phenotype correlation in 95 HS patients genotyped by targeted NGS as part of routine diagnostics (UMC Utrecht, Utrecht, The Netherlands). In 85/95 (89%) of patients a pathogenic mutation was identified, including 56 novel mutations. SPTA1 mutations were most frequently encountered (36%, 31/85 patients), primarily in patients with autosomal recessive forms of HS. Three SPTA1 (α-spectrin) mutations showed autosomal dominant inheritance. ANK1 (ankyrin1) mutations accounted for 27% (23/85 patients) and SPTB (β-spectrin) mutations for 20% (17/85 patients). Moderate or severe HS was more frequent in patients with SPTB or ANK1 mutations, reflected by lower hemoglobin concentrations and higher reticulocyte counts. Interestingly, mutations affecting spectrin association domains of ANK1, SPTA1 and SPTB resulted in more severe phenotypes. Additionally, we observed a clear association between phenotype and aspects of red cell deformability as determined by the Laser assisted Optical Rotational Cell Analyzer (LoRRca MaxSis). Both maximal deformability and area under the curve were negatively associated with disease severity (respectively r = -0.46, p < 0.01, and r = -0.39, p = 0.01). Genotype-phenotype prediction in HS facilitates insight in consequences of pathogenic mutations for the assembly and dynamic interactions of the red cell cytoskeleton. In addition, we show that measurements of red blood cell deformability are clearly correlated with HS severity.

Advances in understanding the pathogenesis of red cell membrane disorders

Hereditary erythrocyte membrane disorders are caused by mutations in genes encoding various transmembrane or cytoskeletal proteins of red blood cells. The main consequences of these genetic alterations are decreased cell deformability and shortened erythrocyte survival. Red blood cell membrane defects encompass a heterogeneous group of haemolytic anaemias caused by either (i) altered membrane structural organisation (hereditary spherocytosis, hereditary elliptocytosis, hereditary pyropoikilocytosis and Southeast Asian ovalocytosis) or (ii) altered membrane transport function (overhydrated hereditary stomatocytosis, dehydrated hereditary stomatocytosis or xerocytosis, familial pseudohyperkalaemia and cryohydrocytosis). Herein we provide a comprehensive review of the recent literature on the molecular genetics of erythrocyte membrane defects and their reported clinical consequences. We also describe the effect of low-expression genetic variants on the high inter- and intra-familial phenotype variability of erythrocyte structural defects.