Abnormalities of the erythrocyte membrane

Molecular insights into hereditary elliptocytosis and pyropoikilocytosis: NGS uncovers multiple potential candidate genes

Hereditary elliptocytosis (HE) and pyropoikilocytosis (HPP) are considered a group of hemolytic anemias (HE/HPP) due to inherited abnormalities of erythrocyte membrane proteins with a worldwide distribution. Most cases are associated with molecular abnormalities linked to spectrin, band 4.1, and ankyrin. The present study aimed to identify significant molecular signatures on a target panel of 8 genes using whole exome sequencing (WES) in 9 Bahraini patients with elliptocytosis. Case selection was based on presence of anemia not associated with iron deficiency or hemoglobinopathy and demonstrating > 50% elliptocytes in blood smears. The c.779 T > C mutation of SPTA1 (Spectrin alpha), which is a known deleterious missense mutation that inhibits normal association of spectrin molecules to form tetramers, was seen in 4 patients in homozygous (n = 1) and heterozygous (n = 3) states. The αLELY abnormality in association with compound heterozygous mutations in SPTA1 was present in 5 patients (2 associated with the SPTA1 c.779 T > C variant; 3 with c.3487 T > G and various other SPTA1 mutations of uncertain/unknown significance). Seven patients had SPTB (Spectrin beta) mutations, predicted as likely benign by in silico analysis. A novel EPB41 (Erythrocyte Membrane Protein Band 4.1) mutation with potential deleterious impact was also seen. Finally, 2 cases showed an InDel (insertion-deletion mutations) abnormality in the gene that codes for the mechanosensitive ion-channel PIEZO (Piezo Type Mechanosensitive Ion Channel Component 1). PIEZO mutations are reported to cause red cell dehydration but have not been previously described in HE/HPP. Results of this study confirm the involvement of previously reported abnormalities in SPTA1 and suggest possible involvement of other candidate genes in a disorder involving polygenic interactions.

Identification of variants in 94 Chinese patients with hereditary spherocytosis by next-generation sequencing

Hereditary spherocytosis (HS) is the most common type of hereditary erythrocyte membrane disease and has varied phenotypic features and genetic patterns. We herein performed a retrospective study of 94 patients with HS and aimed to investigate the genetic variations and genotype-phenotype correlations using targeted next-generation sequencing. In 79/94 (84%) patients, 83 HS variants including 67 novel variants were identified. Pathogenic variants of SPTB, ANK1, SLC4A1, SPTA1, and EPB42 were found in 32/79(41%), 22/79(28%), 15/79 (19%), 8/79 (9%), and 3/79 (4%) of the patients respectively, revealing that SPTB is the most frequently mutated HS gene in Eastern China. Most SPTB and ANK1 gene variations were nonsense and frameshift variations. Missense variants were the main variant type of SLC4A1, SPTA1, and EPB42 genes. Interestingly, one SPTA1 variant (p. Arg1757Cys) showed an autosomal dominant inheritance pattern and one EPB42 variant (p. Gln377His) was apparent as a hotspot variation. Furthermore, genotype-phenotype analysis was performed among the five mutated gene groups. Besides the finding that patients with the SLC4A1 variant had the highest mean corpuscular hemoglobin levels, no clear correlations between genotype and phenotype were observed.

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.

Nanoscale Dynamics of Actin Filaments in the Red Blood Cell Membrane Skeleton

Red blood cell (RBC) shape and deformability are supported by a planar network of short actin filament (F-actin) nodes (∼37 nm length, 15–18 subunits) interconnected by long spectrin strands at the inner surface of the plasma membrane. Spectrin-F-actin network structure underlies quantitative modeling of forces controlling RBC shape, membrane curvature, and deformation, yet the nanoscale organization and dynamics of the F-actin nodes in situ are not well understood. We examined F-actin distribution and dynamics in RBCs using fluorescent-phalloidin labeling of F-actin imaged by multiple microscopy modalities. Total internal reflection fluorescence and Zeiss Airyscan confocal microscopy demonstrate that F-actin is concentrated in multiple brightly stained F-actin foci ∼200–300 nm apart interspersed with dimmer F-actin staining regions. Single molecule stochastic optical reconstruction microscopy imaging of Alexa 647-phalloidin-labeled F-actin and computational analysis also indicates an irregular, nonrandom distribution of F-actin nodes. Treatment of RBCs with latrunculin A and cytochalasin D indicates that F-actin foci distribution depends on actin polymerization, while live cell imaging reveals dynamic local motions of F-actin foci, with lateral movements, appearance and disappearance. Regulation of F-actin node distribution and dynamics via actin assembly/disassembly pathways and/or via local extension and retraction of spectrin strands may provide a new mechanism to control spectrin-F-actin network connectivity, RBC shape, and membrane deformability.

Common host variation drives malaria parasite fitness in healthy human red cells

The replication of Plasmodium falciparum parasites within red blood cells (RBCs) causes severe disease in humans, especially in Africa. Deleterious alleles like hemoglobin S are well-known to confer strong resistance to malaria, but the effects of common RBC variation are largely undetermined. Here, we collected fresh blood samples from 121 healthy donors, most with African ancestry, and performed exome sequencing, detailed RBC phenotyping, and parasite fitness assays. Over one-third of healthy donors unknowingly carried alleles for G6PD deficiency or hemoglobinopathies, which were associated with characteristic RBC phenotypes. Among non-carriers alone, variation in RBC hydration, membrane deformability, and volume was strongly associated with P. falciparum growth rate. Common genetic variants in PIEZO1, SPTA1/SPTB, and several P. falciparum invasion receptors were also associated with parasite growth rate. Interestingly, we observed little or negative evidence for divergent selection on non-pathogenic RBC variation between Africans and Europeans. These findings suggest a model in which globally widespread variation in a moderate number of genes and phenotypes modulates P. falciparum fitness in RBCs.

A novel essential splice site variant in SPTB in a large hereditary spherocytosis family

BACKGROUND

We studied a large family with 22 individuals affected with autosomal dominant hereditary spherocytosis (HS).

METHODS

Genome-wide linkage, whole-genome sequencing (WGS), Sanger sequencing, RT-PCR, and ToPO TA cloning analyses were performed.

RESULTS

We revealed a heterozygous G>A transition in the 14q23 locus, at position +1 of the intron 8 donor splice site of the spectrin beta, erythrocytic (SPTB) gene. This splice variant (SPTB c.1064+1G>A) was confirmed by Sanger sequencing and showed complete co-segregation with HS in the family. Further RT-PCR reactions and sequencing analysis indicated that the variant leads to the exclusion of exon 8 and subsequent frameshift in exon 9 and a premature stop codon in SPTB. Translation of the altered allele would lead to a truncation with a loss of all spectrin repeat domains in SPTB protein.

CONCLUSION

This variant is novel and has not been found in any databases. We propose that this splice variant explains the spherocytosis phenotype observed in this large family.

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.

Identification of a De Novoc.1000delA ANK1 mutation associated to hereditary spherocytosis in a neonate with Coombs-negative hemolytic jaundice-case reports and review of the literature

BACKGROUND

To strengthen the understanding of Hereditary Spherocytosis (HS) and determine the disease-causing mutation present with neonatal jaundice. HS is a hemolytic condition resulting from various erythrocyte membrane defects. Many different mutations result in HS, including mutations in ANK1.

CASE PRESENTATION

A term neonate presented at ten hours with severe jaundice requiring exchange transfusion. At two months he was hospitalized due to repeated pallor and anemia requiring blood transfusions. Using next-generation sequencing, we discovered the responsible mutation in the proband but not in his parents; a heterozygous nucleotide variation of c.1000delA (p.1334Sfs*6) in ANK1. Thus hereditary spherocytosis was diagnosed.

CONCLUSIONS

Genetic detection is an important means of discovering the cause of hemolytic anemia in neonates and infants where routine diagnostic tests are unrevealing. We found a novel de novo mutation, c.1000delA (p.1334Sfs*6) in ANK1 that might account for other cases of HS in the Chinese population.

A Novel α-Spectrin Pathogenic Variant in Trans to α-Spectrin LELY Causing Neonatal Jaundice With Hemolytic Anemia From Hereditary Pyropoikilocytosis Coexisting With Gilbert Syndrome

Hereditary pyropoikilocytosis is a subtype of hereditary elliptocytosis because of biallelic mutations of SPTA1, SPTB, and EPB41. The authors present a proband with neonatal jaundice and hemolytic anemia, with poikilocytosis in the blood film. Targeted next-generation sequencing identified Q267del trans to the αLELY allele in SPTA1. In addition, the proband presented coexisting Gilbert syndrome as determined by homozygous mutation of UGT1A1. Investigation of 13 relatives and his sibling revealed that only his sibling showed the same phenotype and genotype as the proband. This is the first report of molecular confirmation of coexisting hereditary pyropoikilocytosis and Gilbert syndrome and a novel mutation in SPTA1.

Chronic Hemolysis May Adversely Affect Skeletal Health. A Cross-Sectional Study of a Pediatric Population

Hereditary hemolytic disorders cause ineffective erythropoiesis and bone marrow hyperplasia. Little is known about their effect on growth and skeletal health. The aim of this study was to evaluate growth, bone and body composition of non transfusion-dependent (NTD) pediatric patients with chronic hemolysis. A detailed history and clinical examination, dual-energy X-ray absorptiometry (DXA) of the lumbar spine (LS) and total body less head (TBLH) and bone turnover markers were performed. Thirty-nine patients (22 males and 17 females, 20 prepubertal), aged 11.4 ± 3.6 years [14 had β-thalassemia intermedia (β-TI), 17 α-thalassemia (α-thal) and eight hereditary spherocytosis (HS)] were evaluated. Fifty-seven previously studied controls were used for statistical analysis. The patients had lower weight and body mass index (BMI) (Z-scores -0.2 and -0.3, respectively, p < 0.05). Post-traumatic fractures were reported by 28.0% of the patients. Compared to controls, they had lower lumbar and subcranial bone mineral density (BMD), as well as reduced fat mass (FM), whereas muscle mass was not affected. One in three patients had low vitamin D and there was increased bone resorption and reduced bone formation. Correlations between different parameters revealed a potential role of osteocalcin, hemoglobin (Hb) and lactate dehydrogenase (LDH) as prognostic markers for bone health, in the setting of chronic hemolysis. Hereditary spherocytosis (HS) patients were the least affected in terms of growth and bone profile. Chronic hemolysis may lead to impaired growth and bone health, even in young, NTD patients. The degree of hemolysis determines bone health risk. Regular surveillance of bone health is justifiable.

Red cell membrane protein abnormalities as defined by sds-page among patients with anemia in a West African region hospital practice

Background:

Erythrocytes require an ability to deform and withstand shear stress while negotiating microcirculation. These properties are largely due to their excess surface area per volume and the characteristics of the membrane’s protein. Deficiencies of these proteins are associated with chronic hemolysis.

Methods:

This was a cross-sectional study aimed at determining the prevalence of red cell membrane protein abnormalities as determined by sodium dodecyl sulphate polyacrilamide gel electrophoresis (SDS-PAGE) among patients with anemia attending the outpatient clinics of the hospital.

Results:

A total of 823 participants were recruited into the study with a mean age of 34±14 years. There were 410 (49.8%) participants with hematocrit ≥ 36% and 413 with hematocrit ≤ 35.9% of which 192 participants (23.3%) had abnormal red cell indices. Following SDS-PAGE, 21 (10.9%) of the 192 participants had deficient PAGE tracing. Abnormal spectrin band was observed in 17 (81%) of the 21 participants. The hematocrit was significantly lower while the reticulocyte count and red cell distribution width were higher in participants with red cell membrane abnormalities.

Conclusion:

One in ten patients with mild anemia and abnormal red cell indices in clinical practice may be having hereditary red cell membrane protein defect. Presence of raised reticulocyte count, family history of mild anemia, increased red cell distribution width and red cell morphology may be used to screen for membrane deficiency.

Aberrant Membrane Composition and Biophysical Properties Impair Erythrocyte Morphology and Functionality in Elliptocytosis

Red blood cell (RBC) deformability is altered in inherited RBC disorders but the mechanism behind this is poorly understood. Here, we explored the molecular, biophysical, morphological, and functional consequences of α-spectrin mutations in a patient with hereditary elliptocytosis (pEl) almost exclusively expressing the Pro260 variant of SPTA1 and her mother (pElm), heterozygous for this mutation. At the molecular level, the pEI RBC proteome was globally preserved but spectrin density at cell edges was increased. Decreased phosphatidylserine vs. increased lysophosphatidylserine species, and enhanced lipid peroxidation, methemoglobin, and plasma acid sphingomyelinase (aSMase) activity were observed. At the biophysical level, although membrane transversal asymmetry was preserved, curvature at RBC edges and rigidity were increased. Lipid domains were altered for membrane:cytoskeleton anchorage, cholesterol content and response to Ca²⁺ exchange stimulation. At the morphological and functional levels, pEl RBCs exhibited reduced size and circularity, increased fragility and impaired membrane Ca²⁺ exchanges. The contribution of increased membrane curvature to the pEl phenotype was shown by mechanistic experiments in healthy RBCs upon lysophosphatidylserine membrane insertion. The role of lipid domain defects was proved by cholesterol depletion and aSMase inhibition in pEl. The data indicate that aberrant membrane content and biophysical properties alter pEl RBC morphology and functionality.

Exome sequencing for diagnosis of congenital hemolytic anemia

Background

Congenital hemolytic anemia constitutes a heterogeneous group of rare genetic disorders of red blood cells. Diagnosis is based on clinical data, family history and phenotypic testing, genetic analyses being usually performed as a late step. In this study, we explored 40 patients with congenital hemolytic anemia by whole exome sequencing: 20 patients with hereditary spherocytosis and 20 patients with unexplained hemolysis.

Results

A probable genetic cause of disease was identified in 82.5% of the patients (33/40): 100% of those with suspected hereditary spherocytosis (20/20) and 65% of those with unexplained hemolysis (13/20). We found that several patients carried genetic variations in more than one gene (3/20 in the hereditary spherocytosis group, 6/13 fully elucidated patients in the unexplained hemolysis group), giving a more accurate picture of the genetic complexity of congenital hemolytic anemia. In addition, whole exome sequencing allowed us to identify genetic variants in non-congenital hemolytic anemia genes that explained part of the phenotype in 3 patients.

Conclusion

The rapid development of next generation sequencing has rendered the genetic study of these diseases much easier and cheaper. Whole exome sequencing in congenital hemolytic anemia could provide a more precise and quicker diagnosis, improve patients’ healthcare and probably has to be democratized notably for complex cases.

Development of a novel test for the identification of hereditary erythrocyte membrane defects by TGA/Chemometrics

Systematic screening for congenital erythrocyte disorders is not a common practice, due to a lack in the accuracy of the methods and to the costs of the analyses. As a consequence, the diagnosis is usually made when a severe complication occurs. This study introduces an innovative method to perform the screening of a hereditary disease characterized by erythrocyte membrane defects such as hereditary spherocytosis (HS) and hereditary elliptocytosis (HE). Blood samples from healthy donors and patients affected by HS and HE were processed by thermogravimetric analysis (TGA) and the resulting curves were analyzed by chemometrics in order to develop a model of prediction. A novel test was developed and validated by chemometrics and results were found to be in accordance with the genetic diagnosis, confirming the prediction ability of the optimized model that uses few microliters of whole non pretreated blood to perform the diagnosis of HS/HE in less than one hour.

Clinical Diagnosis of Red Cell Membrane Disorders: Comparison of Osmotic Gradient Ektacytometry and Eosin Maleimide (EMA) Fluorescence Test for Red Cell Band 3 (AE1, SLC4A1) Content for Clinical Diagnosis

The measurement of band 3 (AE1, SLC4A1, CD233) content of red cells by eosin-5- maleimide (EMA) staining is swiftly replacing conventional osmotic fragility (OF) test as a tool for laboratory confirmation of hereditary spherocytosis across the globe. Our group has systematically evaluated the EMA test as a method to screen for a variety of anemias in the last 10 years, and compared these results to those obtained with the osmotic gradient ektacytometry (osmoscans) which we have used over three decades. Our overall experience allowed us to characterize the distinctive patterns with the two tests in several congenital erythrocyte membrane disorders, such as hereditary spherocytosis (HS), hereditary elliptocytosis (HE), Southeast Asian Ovalocytosis (SAO), hereditary pyropoikilocytosis (HPP) variants, erythrocyte volume disorders, various red cell enzymopathies, and hemoglobinopathies. A crucial difference between the two methodologies is that osmoscans measure red blood cell deformability of the entire sample of RBCs, while the EMA test examines the band 3 content of individual RBCs. EMA content is influenced by cell size as smaller red cells have lower amount of total membrane than larger cells. The SAO mutation alters the EMA binding site resulting in a lower EMA MCF even as the band 3 content itself is unchanged. Thus, EMA scan results should be interpreted with caution and both the histograms and dot plots should be analyzed in the context of the clinical picture and morphology.

Concomitant Laparoscopic Splenectomy and Cholecystectomy: A Systematic Review of the Literature

Background: Concomitant laparoscopic splenectomy and cholecystectomy (CLSC) is performed for concurrent pathologies of the spleen and gallbladder. This systematic review aimed to evaluate the available evidence on its indications, operative technique, and outcomes. Materials and Methods: The PubMed and Cochrane bibliographical databases were searched from the beginning of time (last search: December 6, 2019) for studies reporting on CLSC. The National Heart, Lung, and Blood Institute (NHLBI) quality assessment tool was utilized for the evaluation of eligible articles. Results: Eight studies met inclusion criteria and concerned collectively 108 patients (53 males and 55 females) with a mean age of 27.02 ± 20.48 years (mean, SD). The most common surgery indications were hereditary spherocytosis (38.9%) and sickle cell disease or β-thalassemia (32.4%). Laparoscopic cholecystectomy preceded splenectomy in the majority of cases (75%). A five-trocar approach was most frequently (89.8%) utilized. The mean operation duration was 170.18 ± 53.07 minutes (mean, SD). Resected spleen weight was 601.82 ± 386.02 g (mean, SD) and had a length of 18.74 ± 5.3 cm (mean, SD). The conversion rate was 2.7%, while 20.4% of included cases experienced postoperative complications. Most frequent ones included pulmonary infection (6.5%) and portal/splenic vein thrombosis (4.6%). No postoperative death was recorded. Mean hospitalization period was 5.43 ± 3.18 days (mean, SD). Conclusions: CLSC is a safe and feasible operation for simultaneous diseases of the spleen and gallbladder that require elective procedures. High-quality clinical trials are essential to further elucidate clinical evidence and standardize operative technique.

Nano-scientific Application of Atomic Force Microscopy in Pathology: from Molecules to Tissues

The advantages of atomic force microscopy (AFM) in biological research are its high imaging resolution, sensitivity, and ability to operate in physiological conditions. Over the past decades, rigorous studies have been performed to determine the potential applications of AFM techniques in disease diagnosis and prognosis. Many pathological conditions are accompanied by alterations in the morphology, adhesion properties, mechanical compliances, and molecular composition of cells and tissues. The accurate determination of such alterations can be utilized as a diagnostic and prognostic marker. Alteration in cell morphology represents changes in cell structure and membrane proteins induced by pathologic progression of diseases. Mechanical compliances are also modulated by the active rearrangements of cytoskeleton or extracellular matrix triggered by disease pathogenesis. In addition, adhesion is a critical step in the progression of many diseases including infectious and neurodegenerative diseases. Recent advances in AFM techniques have demonstrated their ability to obtain molecular composition as well as topographic information. The quantitative characterization of molecular alteration in biological specimens in terms of disease progression provides a new avenue to understand the underlying mechanisms of disease onset and progression. In this review, we have highlighted the application of diverse AFM techniques in pathological investigations.

Laboratory Approach to Hemolytic Anemia

Hemolytic anemias are a group of disorders with varied clinical and molecular heterogeneity. They are characterized by decreased levels of circulating erythrocytes in blood. The pathognomic finding is a reduced red cell life span with severe anemia or, compensated hemolysis accompanied by reticulocytosis. The diagnostic workup or laboratory approach for hemolytic anemias is based on methodical step-wise testing which includes red blood cell morphology, hematological indices with increased reticulocyte count along with clinical features of hemolytic anemias. If conventional laboratory tests are unable to detect the underlying cause of hemolysis, genetic testing is recommended. Sanger sequencing along with conventional testing is the most efficient way to diagnose the underlying genetic causes, especially in thalassemias/hemoglobinopathies, if required. However, hemolytic anemias being highly heterogeneous disorders, next-generation sequencing-based screening is rapidly becoming an efficient way to decipher the etiologies where common causes have been excluded.

A family affair-Severe fetal and neonatal hemolytic anemia due to novel alpha-spectrin mutations in two siblings

Hereditary spherocytosis (HS) is the most common cause of inherited, nonimmune hemolytic anemia. When inherited in an autosomal dominant fashion, the anemia is typically mild. However, severe, transfusion-dependent anemia is seen in autosomal recessive HS, which is often associated with deficient or absent red blood cell membrane protein alpha-spectrin. We report a 26-year-old para one who was referred to our center at 28 weeks' gestation due to concerns for fetal anemia. Evaluation revealed elevated peak systolic velocity in the middle cerebral artery by Doppler scan and fetal cardiomegaly. Fetal hematocrit obtained by sampling the umbilical vein was 9% confirming severe fetal anemia. Fetal peripheral smear was consistent with hereditary spherocytosis. Genetic analysis of both parents confirmed heterozygosity for the SPTA1 variants (pathogenic variant c.4180del (p.C1394Afs*25), and a variant of uncertain significance, c.1677G>T (p.G449G)) detected by a hemolytic anemia panel in the patient's first child. It is important to consider genetic causes of anemia in patients presenting with severe nonimmune fetal anemia, including autosomal recessive HS. We present a case of autosomal recessive HS with a novel pathogenic variant in the SPTA1 gene which resulted in significant impact on prenatal management.

Applications of imaging flow cytometry in the diagnostic assessment of red cell membrane disorders

BACKGROUND

Red cell membranopathies refers to phenotypically and morphologically heterogeneous disorders. High throughput imaging flow cytometry (IFC) combines the speed, sensitivity, and phenotyping abilities of flow cytometry with the detailed imagery and functional insights of microscopy to produce high content image analysis with quantitative analysis. We have evaluated the applications of IFC to examine both the morphology as well as fluorescence signal intensity in red cell membranopathies.

METHODS

Fluorescence intensity of eosin-5-maleimide (EMA) labeled red cells was measured for diagnosis of RBC membrane protein defect on Amnis ImageStreamX followed by Image analysis on IDEAS software to study features such as circularity and shape ratio.

RESULTS

The hereditary spherocytosis (HS) group showed significantly decreased MFI (52,800 ± 9,100) than normal controls (81,100 ± 4,700) (p < .05) whereas non-HS showed 78,300 ± 9,900. The shape ratio of hereditary elliptocytosis (HE) was significantly higher (43.8%) than normal controls (14.6%). The circularity score is higher in HS (64.15%) than the normal controls (44.3%) whereas the circularity score was very less in HE (10%) due to the presence of elliptocytes.

CONCLUSIONS

The advantages of the IFC over standard flow cytometry is its ability to provide high-content image analysis and measurement of parameters such as circularity and shape ratio allow discriminating red cell membranopathies (HS and HE) due to variations in shape and size. It could be a single, effective, and rapid IFC test for detection and differentiation of red cell membrane disorders in hematology laboratories where an IFC is available.

The Spectrinome: The Interactome of a Scaffold Protein Creating Nuclear and Cytoplasmic Connectivity and Function

We provide a review of Spectrin isoform function in the cytoplasm, the nucleus, the cell surface, and in intracellular signaling. We then discuss the importance of Spectrin’s E2/E3 chimeric ubiquitin conjugating and ligating activity in maintaining cellular homeostasis. Finally we present spectrin isoform subunit specific human diseases. We have created the Spectrinome, from the Human Proteome, Human Reactome and Human Atlas data and demonstrated how it can be a useful tool in visualizing and understanding spectrins myriad of cellular functions.

Impact statement

Spectrin was for the first 12 years after its discovery thought to be found only in erythrocytes. In 1981, Goodman and colleagues1found that spectrin-like molecules were ubiquitously found in non-erythroid cells leading to a great multitude of publications over the next thirty eight years. The discovery of multiple spectrin isoforms found associated with every cellular compartment, and representing 2-3% of cellular protein, has brought us to today’s understanding that spectrin is a scaffolding protein, with its own E2/E3 chimeric ubiquitin conjugating ligating activity that is involved in virtually every cellular function. We cover the history, localized functions of spectrin isoforms, human diseases caused by mutations, and provide the spectrinome: a useful tool for understanding the myriad of functions for one of the most important proteins in all eukaryotic cells.

Clinical and laboratory outcomes following total or partial splenectomy in patients with hereditary spherocytosis

This study compared outcomes following total (TS) or partial splenectomy (PS) among patients with hereditary spherocytosis. Seventy-nine patients (TS = 33, PS = 46) were identified. The follow-up period was longer after PS (59.6 vs. 24.9 months, p < .001). Long-term adverse events occurred more frequently following PS (50% vs. 29%, p = .001). Anemia, jaundice, and fatigue recurred in six patients with PS, leading to five completion splenectomies. Hemoglobin was not different between PS and TS by 5 years post-procedure (12.3 vs. 13.4 g/dL, p = .25). Both PS and TS ameliorate symptoms and improve hematologic parameters. The rate of secondary surgery following PS should be considered when planning the initial surgical procedure.

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.

Aberrant splicing contributes to severe α-spectrin-linked congenital hemolytic anemia

The etiology of severe hemolytic anemia in most patients with recessive hereditary spherocytosis (rHS) and the related disorder hereditary pyropoikilocytosis (HPP) is unknown. Whole exome sequencing of DNA from probands of 24 rHS or HPP kindreds identified numerous mutations in erythrocyte membrane α-spectrin (SPTA1). Twenty-eight mutations were novel, with null alleles frequently found in trans to missense mutations. No mutations were identified in a third of SPTA1 alleles (17/48). Whole genome sequencing revealed linkage disequilibrium between the common rHS-linked α-spectrinBug Hill polymorphism and a rare intron 30 variant in all 17 mutation-negative alleles. In vitro minigene studies and in vivo splicing analyses revealed the intron 30 variant changes a weak alternate branch point (BP) to a strong BP. This change leads to increased utilization of an alternate 3' splice acceptor site, perturbing normal α-spectrin mRNA splicing and creating an elongated mRNA transcript. In vivo mRNA stability studies revealed the newly created termination codon in the elongated transcript activates nonsense mediated decay leading to spectrin deficiency. These results demonstrate a unique mechanism of human genetic disease contributes to the etiology of a third of cases of rHS, facilitating diagnosis and treatment of severe anemia, and identifying a new target for therapeutic manipulation.

[Clinical characteristics and genetic analysis of hereditary spherocytosis caused by mutations of ANK1 and SPTB genes]

This study analyzed the clinical features of 5 children with hereditary spherocytosis (HS) and the characteristics of ANK1 and SPTB gene mutations. All 5 children were confirmed with HS by peripheral blood genetic detection. Anemia, jaundice and splenomegaly were observed in all 5 children. Three children had an increase in erythrocyte osmotic fragility. All 5 children had negative results of the Coombs test, glucose 6 phosphate dehydrogenase test, sucrose hemolysis test, acidified-serum hemolysis test and thalassemia gene test. Peripheral blood smear showed an increase in spherocyte count in one child. High-throughput sequencing revealed ANK1 gene mutations in patients 1 to 3, namely c.3398(exon29)delA, c.4306C>T and c.957(exon9)_c.961(exon9)delAATCT, among which c.3398(exon29)delA had not been reported before. Patient 4 had c.318delGExon3 mutation in the SPTB gene. Patient 5 had mutations in the SPTB and SLC4A1 genes, among which c.3484delC in the SPTB gene was a spontaneous mutation; the mutation site of the SLCA4A1 gene was inherited from the father and was a non-pathogenic gene. This study suggests that anemia, jaundice and splenomegaly are major clinical manifestations of HS children. Most children with HS do not have the typical spherocytic changes. Genetic detection may help with the accurate diagnosis of HS.

Identification of red blood cell membrane defects in a patient with hereditary spherocytosis using next‑generation sequencing technology and matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry

Hereditary spherocytosis (HS) is characterized by the morphological transformation of erythrocytes into a spherical shape due to a hereditary defect in cell membrane proteins (ghosts) associated with disruption of erythrocyte skeletal structures. Contrary to the literature, pores were detected in the erythrocytes of a patient with HS. The aim of the present study was to determine the affected proteins and genes that were responsible for the pores. Ghost isolation was performed to determine the proteins responsible for the pores observed on the erythrocytes of the patient. Erythrocyte membrane proteins were visualized using SDS‑PAGE. Exome and matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry (MALDI TOF MS) analyses were used to identify the genes and proteins responsible for the observed defect. Quantitative protein assessments were performed using MALDI TOF MS. A difference was detected in the components of the erythrocyte membrane proteins. Band 3 and protein 4.2, which serve a particular role in membrane structure, decreased 4.573 and 4.106 fold, respectively. Through proteomic analyses, a non‑synonymous exonic mutation region was identified in the Golgi membrane protein 1 (GOLM1) gene (Chr9 rs142242230). Sorting Intolerant From Tolerant and Polymorphism Phenotyping Scores, Likelihood Ratio Tests and MutationTaster revealed that the mutation was deleterious. The pores observed in the morphology of the erythrocytes may have developed due to the decrease in these proteins, which reside in the erythrocyte membrane structure. Furthermore, genetic profiling of the patient with HS and her family was conducted in the present study. Next‑generation sequencing was used, and the genetic source of HS was identified as a GOLM1 gene mutation. The assessment of specific molecular defects is often not performed as the majority of mutations are unique to a family. However, molecular analyses should be performed in severe cases where prenatal diagnosis is required, or for unique HS phenotypes to aid scientific investigation.

The Shape Shifting Story of Reticulocyte Maturation

The final steps of erythropoiesis involve unique cellular processes including enucleation and reorganization of membrane proteins and the cytoskeleton to produce biconcave erythrocytes. Surprisingly this process is still poorly understood. In vitro erythropoiesis protocols currently produce reticulocytes rather than biconcave erythrocytes. In addition, immortalized lines and iPSC-derived erythroid cell suffer from low enucleation and suboptimal final maturation potential. In light of the increasing prospect to use in vitro produced erythrocytes as (personalized) transfusion products or as therapeutic delivery agents, the mechanisms driving this last step of erythropoiesis are in dire need of resolving. Here we review the elusive last steps of reticulocyte maturation with an emphasis on protein sorting during the defining steps of reticulocyte formation during enucleation and maturation.

Cryohemolysis, erythrocyte osmotic fragility, and supplementary hematimetric indices in the diagnosis of hereditary spherocytosis

Background

Hereditary spherocytosis (HS) is a chronic hemolytic anemia characterized by microspherocytes in the peripheral blood and increased erythrocyte osmotic fragility (EOF). This study evaluated the cryohemolysis test (CHT); initial hemolysis (IH); immediate and incubated hemolysis percentage in 5.5 g/L NaCl (H5.5); mean corpuscular hemoglobin concentration (MCHC); red blood cell distribution width (RDW); and Hb/MCHC, Hb/RDW, and MCHC/RDW ratios for the diagnosis of HS.

Methods

Data from 13 patients with HS were evaluated at the Instituto de Bioquímica Aplicada and compared with data from 14 unaffected individuals and 11 patients with anemia due to another etiology. Total blood and reticulocyte counts, CHT, and immediate and incubated EOF were performed in all subjects; sensitivity, specificity, efficiency, and Youden index (YI) were calculated.

Results

Eight patients with HS had MCHC ≥345 g/L, 10 had RDW ≥14.5%, 12 had IH >5.0 g/L, 11 had immediate H5.5 ≥5%, and 13 had incubated H5.5 ≥50% (the cut-off value to consider HS). The efficiency and YI were: immediate H5.5 (0.94–0.85), incubated H5.5 (0.89–0.82), IH (0.89–0.78), MCHC (0.87–0.62), CHT (0.84–0.54), and Hb/MCHC (0.71–0.56), respectively. The calculated ratios could distinguish subjects with HS from unaffected individuals (P<0.05), but not those with anemia of another etiology (P>0.05).

Conclusion

Although the CHT and supplementary hematimetric indexes were useful to differentiate individuals with SH from healthy controls, they cannot distinguish from anemias of other etiology. CHT and MCHC, in addition to EOF, are recommended for diagnosing HS patients because of their low cost and efficiency.

Three Novel Spectrin Variants in Jaundiced Neonates

Various mutations in the genes encoding alpha spectrin (SPTA1) or beta spectrin (SPTB) are known to cause erythrocyte membrane disorders, sometimes associated with severe neonatal jaundice and anemia. We used a next-generation sequencing panel to evaluate 3 unrelated neonates who had puzzling cases of nonimmune hemolytic jaundice. In each case, we identified novel mutations in either SPTA1 or SPTB. Correlating erythrocyte morphology, clinical course, and computational analysis, we submit that each of the 3 variants is a probable pathogenic cause of the hereditary hemolytic conditions in these patients. We hope other pediatric practitioners caring for neonates with what appears to be idiopathic severe neonatal hyperbilirubinemia will look for spectrin variants as a possible cause, because additional cases with these specific variants along with this clinical phenotype are needed to confirm our postulate that these 3 cases are indeed pathogenic mutations.

Stabilization of F-actin by tropomyosin isoforms regulates the morphology and mechanical behavior of red blood cells

The absence of Tpm3.1 in red blood cells (RBCs) induces a compensatory increase in Tpm1.9 and abnormally stable F-actin in the membrane skeleton, with reduced association of Band 3 and glycophorin A, leading to a compensated hemolytic anemia with abnormal RBC shapes and mechanical properties.

The short F-actins in the red blood cell (RBC) membrane skeleton are coated along their lengths by an equimolar combination of two tropomyosin isoforms, Tpm1.9 and Tpm3.1. We hypothesized that tropomyosin’s ability to stabilize F-actin regulates RBC morphology and mechanical properties. To test this, we examined mice with a targeted deletion in alternatively spliced exon 9d of Tpm3 (Tpm3/9d^–/–), which leads to absence of Tpm3.1 in RBCs along with a compensatory increase in Tpm1.9 of sufficient magnitude to maintain normal total tropomyosin content. The isoform switch from Tpm1.9/Tpm3.1 to exclusively Tpm1.9 does not affect membrane skeleton composition but causes RBC F-actins to become hyperstable, based on decreased vulnerability to latrunculin-A–induced depolymerization. Unexpectedly, this isoform switch also leads to decreased association of Band 3 and glycophorin A with the membrane skeleton, suggesting that tropomyosin isoforms regulate the strength of F-actin-to-membrane linkages. Tpm3/9d^–/– mice display a mild compensated anemia, in which RBCs have spherocytic morphology with increased osmotic fragility, reduced membrane deformability, and increased membrane stability. We conclude that RBC tropomyosin isoforms directly influence RBC physiology by regulating 1) the stability of the short F-actins in the membrane skeleton and 2) the strength of linkages between the membrane skeleton and transmembrane glycoproteins.

Recommendations regarding splenectomy in hereditary hemolytic anemias

Hereditary hemolytic anemias are a group of disorders with a variety of causes, including red cell membrane defects, red blood cell enzyme disorders, congenital dyserythropoietic anemias, thalassemia syndromes and hemoglobinopathies. As damaged red blood cells passing through the red pulp of the spleen are removed by splenic macrophages, splenectomy is one possible therapeutic approach to the management of severely affected patients. However, except for hereditary spherocytosis for which the effectiveness of splenectomy has been well documented, the efficacy of splenectomy in other anemias within this group has yet to be determined and there are concerns regarding short- and long-term infectious and thrombotic complications. In light of the priorities identified by the European Hematology Association Roadmap we generated specific recommendations for each disorder, except thalassemia syndromes for which there are other, recent guidelines. Our recommendations are intended to enable clinicians to achieve better informed decisions on disease management by splenectomy, on the type of splenectomy and the possible consequences. As no randomized clinical trials, case control or cohort studies regarding splenectomy in these disorders were found in the literature, recommendations for each disease were based on expert opinion and were subsequently critically revised and modified by the Splenectomy in Rare Anemias Study Group, which includes hematologists caring for both adults and children.

[Application of systematic etiological analysis in final and differential diagnosis of hereditary hemolytic anemia]

目的

探讨溶血病因系统分析策略在遗传性溶血性贫血病因诊断和鉴别诊断中的应用。

方法

以溶血病因系统分析方法对疑诊溶血性贫血的1 506例患者进行分析。

结果

①1 506例疑诊溶血性贫血患者中，男799例，女707例，中位年龄22岁（4 d~86岁）。涉及三大遗传性溶血病因的患者共1 413例（94%），其中单一病因溶血1 044例（74%），复合型溶血369例（26%）。②在涉及三大遗传性溶血病因的患者中，单一病因血红蛋白病、红细胞膜病及红细胞酶病分别为235例（22%）、656例（63%）及153例（15%）。单一溶血病因与复合溶血病因合并统计，涉及血红蛋白病、红细胞膜病及红细胞酶病分别为489例（29%）、948例（57%）及239例（14%）。上述两种基数统计的三大遗传性溶血病因构成比差异均无统计学意义（P值均>0.05）。③369例（26%）复合型溶血中，不同类型遗传缺陷以血红蛋白病合并红细胞膜病最常见（50%，184/369），亦见于红细胞酶病合并红细胞膜病（18%，66/369），血红蛋白病合并红细胞酶病（4%，13/369）。相同类型遗传缺陷复合型血红蛋白病、复合型膜病、复合型酶病分别为29例（8%）、57例（15%）、9例（2%）。其他复合型溶血、贫血、黄疸占3%（11例），见于合并后天因素、继发因素及其他系统异常。

结论

三大遗传性溶血病因同期检查能对94％的患者进行分类，常见的遗传性溶血病因依次为红细胞膜病、血红蛋白病和红细胞酶病。复合型溶血并非少见，仅单一因素分析不足以提供充分确诊依据。

New insights on hereditary erythrocyte membrane defects

After the first proposed model of the red blood cell membrane skeleton 36 years ago, several additional proteins have been discovered during the intervening years, and their relationship with the pathogenesis of the related disorders have been somewhat defined. The knowledge of erythrocyte membrane structure is important because it represents the model for spectrin-based membrane skeletons in all cells and because defects in its structure underlie multiple hemolytic anemias. This review summarizes the main features of erythrocyte membrane disorders, dividing them into structural and altered permeability defects, focusing particularly on the most recent advances. New proteins involved in alterations of the red blood cell membrane permeability were recently described. The mechanoreceptor PIEZO1 is the largest ion channel identified to date, the fundamental regulator of erythrocyte volume homeostasis. Missense, gain-of-function mutations in the PIEZO1 gene have been identified in several families as causative of dehydrated hereditary stomatocytosis or xerocytosis. Similarly, the KCNN4 gene, codifying the so called Gardos channel, has been recently identified as a second causative gene of hereditary xerocytosis. Finally, ABCB6 missense mutations were identified in different pedigrees of familial pseudohyperkalemia. New genomic technologies have improved the quality and reduced the time of diagnosis of these diseases. Moreover, they are essential for the identification of the new causative genes. However, many questions remain to solve, and are currently objects of intensive studies.

Exome sequencing results in successful diagnosis and treatment of a severe congenital anemia

Whole-exome sequencing is increasingly used for diagnosis and identification of appropriate therapies in patients. Here, we present the case of a 3-yr-old male with a lifelong and severe transfusion-dependent anemia of unclear etiology, despite an extensive clinical workup. Given the difficulty of making the diagnosis and the potential side effects from performing interventions in patients with a congenital anemia of unknown etiology, we opted to perform whole-exome sequencing on the patient and his parents. This resulted in the identification of homozygous loss-of-function mutations in the EPB41 gene, encoding erythrocyte protein band 4.1, which therefore causes a rare and severe form of hereditary elliptocytosis in the patient. Based on prior clinical experience in similar patients, a surgical splenectomy was performed that resulted in subsequent transfusion independence in the patient. This case illustrates how whole-exome sequencing can lead to accurate diagnoses (and exclusion of diagnoses where interventions, such as splenectomy, would be contraindicated), thereby resulting in appropriate and successful therapeutic intervention—a major goal of precision medicine.

Hemolysis in Preterm Neonates

Hemolysis can be an important cause of hyperbilirubinemia in premature and term neonates. It can result from genetic abnormalities intrinsic to or factors exogenous to normal to red blood cells (RBCs). Hemolysis can lead to a relatively rapid increase in total serum/plasma bilirubin, hyperbilirubinemia that is somewhat slow to fall with phototherapy, or hyperbilirubinemia that is likely to rebound after phototherapy. Laboratory methods for diagnosing hemolysis are more difficult to apply, or less conclusive, in preterm infants. Transfusion of donor RBCs can present a bilirubin load that must be metabolized. Genetic causes can be identified by next-generation sequencing panels.

Improved harmonization of eosin-5-maleimide binding test across different instruments and age groups

BACKGROUND

The eosin-5'maleimide (EMA) binding test has been studied extensively for the detection of hereditary spherocytosis (HS). Its performance characteristics have been compared to NaCl-based or glycerol lysis-based red cell osmotic fragility tests and cryohemolysis. HS samples are also better identified when both mean channel fluorescence (MCF) of EMA relative to controls and the coefficient of variation (CV) are analyzed.

METHODS

We looked at 65 normal controls including 30 adults 25-65 years old and 35 newborns and 12 HS cases. In addition to the MCF and the CV, we used a side scatter (SSC) vs. EMA fluorescence gate or "footprint" to depict where normal erythrocytes should appear. Erythrocytes that have reduced band 3 protein appear outside of the footprint.

RESULTS

In our study, newborn data did not cluster with the samples from working age individuals. The MCF and the CVs of normal newborns were higher than normal adult group. However, the footprint data of normal samples relative to their controls was around 99.5% for each group, because the footprint was moved to fit the pattern of the normal.

CONCLUSIONS

The inclusion of footprint parameter will help in better standardization as well as implementation of this test across different age groups as well as different instruments. © 2015 International Clinical Cytometry Society.

A pediatrician's practical guide to diagnosing and treating hereditary spherocytosis in neonates

Newborn infants who have hereditary spherocytosis (HS) can develop anemia and hyperbilirubinemia. Bilirubin-induced neurologic dysfunction is less likely in these neonates if the diagnosis of HS is recognized and appropriate treatment provided. Among neonates listed in the USA Kernicterus Registry, HS was the third most common underlying hemolytic condition after glucose-6-phosphate dehydrogenase deficiency and ABO hemolytic disease. HS is the leading cause of direct antiglobulin test (direct Coombs) negative hemolytic anemia requiring erythrocyte transfusion in the first months of life. We anticipate that as physicians become more familiar with diagnosing HS in the newborn period, fewer neonates with HS will develop hazardous hyperbilirubinemia or present to emergency departments with unanticipated symptomatic anemia. We predict that early suspicion, prompt diagnosis and treatment, and anticipatory guidance will prevent adverse outcomes in neonates with HS. The purpose of this article was to review the neonatal presentation of HS and to provide practical and up-to-date means of diagnosing and treating HS in neonates.

Evaluating eosin-5-maleimide binding as a diagnostic test for hereditary spherocytosis in newborn infants

OBJECTIVE

Neonates with undiagnosed hereditary spherocytosis (HS) are at risk for developing hazardous hyperbilirubinemia and anemia. Making an early diagnosis of HS in a neonate can prompt anticipatory guidance to prevent these adverse outcomes. A recent comparison study showed that a relatively new diagnostic test for HS, eosin-5-maleimide (EMA)-flow cytometry, performs better than other available tests in confirming HS. However, reports have not specifically examined the performance of this test among neonates.

STUDY DESIGN

We compared EMA-flow cytometry from blood samples of healthy control neonates vs samples from neonates suspected of having HS on the basis of severe Coombs-negative jaundice and spherocytes on blood film. The diagnosis of HS was later either confirmed or excluded based on clinical findings and next generation sequencing (NGS) after which we correlated the EMA-flow results with the diagnosis.

RESULT

EMA-flow was performed on the blood of 31 neonates; 20 healthy term newborns and 11 who were suspected of having HS. Eight of the 11 were later confirmed positive for HS and one was confirmed positive for hereditary elliptocytosis (HE). All nine had persistently abnormal erythroid morphology, reticulocytosis and anemia, and eight of the nine had relevant mutations discovered using NGS. The other was confirmed positive for HS on the basis that a parent had HS, and the neonate's spherocytosis, reticulocytosis and anemia persisted. The 20 healthy controls and the 2 in whom HS was initially suspected but later excluded all had EMA-flow results in the range reported in healthy children and adults. In contrast, all nine in whom HS or HE was confirmed had abnormal EMA-flow results consistent with previous reports in older children and adults with HS.

CONCLUSION

Although our sample size is small, our findings are consistent with the literature in older children and adults suggesting that EMA-flow cytometric testing performs well in supporting the diagnosis of HS/HE during the early neonatal period.

ICSH guidelines for the laboratory diagnosis of nonimmune hereditary red cell membrane disorders

INTRODUCTION

Hereditary spherocytosis (HS), hereditary elliptocytosis (HE), and hereditary stomatocytosis (HSt) are inherited red cell disorders caused by defects in various membrane proteins. The heterogeneous clinical presentation, biochemical and genetic abnormalities in HS and HE have been well documented. The need to raise the awareness of HSt, albeit its much lower prevalence than HS, is due to the undesirable outcome of splenectomy in these patients.

METHODS

The scope of this guideline is to identify the characteristic clinical features, the red cell parameters (including red cell morphology) for these red cell disorders associated, respectively, with defective cytoskeleton (HS and HE) and abnormal cation permeability in the lipid bilayer (HSt) of the red cell. The current screening tests for HS are described, and their limitations are highlighted.

RESULTS

An appropriate diagnosis can often be made when the screening test result(s) is reviewed together with the patient's clinical/family history, blood count results, reticulocyte count, red cell morphology, and chemistry results. SDS-polyacrylamide gel electrophoresis of erythrocyte membrane proteins, monovalent cation flux measurement, and molecular analysis of membrane protein genes are specialist tests for further investigation.

CONCLUSION

Specialist tests provide additional evidence in supporting the diagnosis and that will facilitate the management of the patient. In the case of a patient's clinical phenotype being more severe than the affected members within the immediate family, molecular testing of all family members is useful for confirming the diagnosis and allows an insight into the molecular basis of the abnormality such as a recessive mode of inheritance or a de novo mutation.