Molecular Genetic Mechanisms of Hereditary Spherocytosis: Current Perspectives

Genetics of Gallstone Disease and Their Clinical Significance: A Narrative Review

Gallstone (GS) disease is common and arises from a combination of genetic and environmental factors. Although genetic abnormalities specifically leading to cholesterol GSs are rare, there are clinically significant gene variants associated with cholesterol GSs. In contrast, most bilirubin GSs can be attributed to genetic defects. The pathogenesis of cholesterol and bilirubin GSs differs greatly. Cholesterol GSs are notably influenced by genetic variants within the ABC protein superfamily, including ABCG8, ABCG5, ABCB4, and ABCB11, as well as genes from the apolipoprotein family such as ApoB100 and ApoE (especially the E3/E3 and E3/E4 variants), and members of the MUC family. Conversely, bilirubin GSs are associated with genetic variants in highly expressed hepatic genes, notably UGT1A1, ABCC2 (MRP2), ABCC3 (MRP3), CFTR, and MUC, alongside genetic defects linked to hemolytic anemias and conditions impacting erythropoiesis. While genetic cases constitute a small portion of GS disease, recognizing genetic predisposition is essential for proper diagnosis, treatment, and genetic counseling.

Hereditary spherocytosis in a young female in Eastern Nepal: a case report

Introduction and importance

Hereditary spherocytosis (HS), a rare familial extravascular haemolytic disorder, typically follows an autosomal dominant inheritance pattern with variable expressivity. Despite its classical presentation of anaemia, jaundice, and splenomegaly, HS is infrequently reported among individuals of Asian descent, contributing to its under diagnosis or delayed diagnosis. The primary objective of this case report is to underscore the pivotal role of the osmotic fragility test in diagnosing HS, emphasizing the importance of accurate and timely identification for effective clinical management and improved patient outcomes.

Case presentation

The patient, without known prior co-morbidities, presented with recurrent abdominal distension, early satiety, and easy fatigability persisting for 6 years. Physical examination revealed icterus, gnathopathy, left hypochondrium tenderness, and palpable splenomegaly. The osmotic fragility of red cells was significantly elevated. The patient underwent optimization before splenectomy, receiving immunization against encapsulated bacteria. Packed red blood cell transfusions were administered to achieve optimal haemoglobin levels. Follow-up showed symptom relief, significantly improving the patient's quality of life.

Clinical discussion

This case underscores the challenges of delayed HS diagnosis, with the patient enduring symptoms for years before seeking appropriate medical attention. Overlooking the simplicity and cost-effectiveness of an osmotic fragility test prolonged the diagnostic journey, emphasizing the impact on overall well-being.

Conclusion

HS remains underdiagnosed, especially in our regions. The osmotic fragility test emerges as an economical diagnostic tool in resource-limited settings, particularly when spherocytosis is absent in the peripheral blood smears. Its inclusion in diagnostic protocols can expedite accurate HS identification and enhance patient outcomes.

Reticulocyte Antioxidant Enzymes mRNA Levels versus Reticulocyte Maturity Indices in Hereditary Spherocytosis, β-Thalassemia and Sickle Cell Disease

The antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and peroxiredoxin 2 (Prx2) are particularly important in erythroid cells. Reticulocytes and other erythroid precursors may adapt their biosynthetic mechanisms to cell defects or to changes in the bone marrow environment. Our aim was to perform a comparative study of the mRNA levels of CAT, GPX1, PRDX2 and SOD1 in reticulocytes from healthy individuals and from patients with hereditary spherocytosis (HS), sickle cell disease (SCD) and β-thalassemia (β-thal), and to study the association between their transcript levels and the reticulocyte maturity indices. In controls, the enzyme mRNA levels were significantly correlated with reticulocyte maturity indices for all genes except for SOD1. HS, SCD and β-thal patients showed younger reticulocytes, with higher transcript levels of all enzymes, although with different patterns. β-thal and HS showed similar reticulocyte maturity, with different enzyme mRNA levels; SCD and HS, with different reticulocyte maturity, presented similar enzyme mRNA levels. Our data suggest that the transcript profile for these antioxidant enzymes is not entirely related to reticulocyte maturity; it appears to also reflect adaptive mechanisms to abnormal erythropoiesis and/or to altered erythropoietic environments, leading to reticulocytes with distinct antioxidant potential according to each anemia.

Novel mutation in alpha-spectrin gene in Saudi patients with hereditary spherocytosis

Hereditary spherocytosis (HS) is the most common hereditary hemolytic disorder induced by red blood cell (RBC) membrane defect. This study was undertaken to determine mutations in genes associated with RBC membrane defect in patients with HS such as α-spectrin gene (SPTA1), β-spectrin gene (SPTB), ankyrin gene (ANK1), band 3 anion transport gene (SLC4A1) and erythrocyte membrane protein band 4.1 gene (EPB41). Blood samples were collected from 23 unrelated patients with HS. Patients were diagnosed according to the guidelines from the British Society for Hematology. All hematological examinations for the determination of RBC abnormalities and osmotic fragility tests were conducted. Genomic DNA were extracted from peripheral blood cells and coding exons of known genes for hereditary spherocytosis were enriched using Roche/KAPA sequence capture technology and sequenced on an Illumina system via next-generation sequencing (NGS). The data showed that most of the HS patients confirmed splenomegaly and showed elevated reticulocytes and abnormal bilirubin values. NGS analysis identified the heterozygous variant c.5501G > A in the exon 39 of SPTA1 gene, resulted in a Trp1834*, which leads to a premature stop codon and subsequent mRNA degradation (nonsense- mediated decay) or truncation in α spectrin. Moreover, our data also revealed conventional mutations in genes SPTB, ANK, SLC4A1 and EBP41 in severe patients of HS. In short, this is the first report that determined a novel mutation c.5501G > A in SPTA1 gene in the Saudi population. To the best of our knowledge, this variant c.5501G > A has not been described in global literature so far. This novel mutation in SPTA1 gene is unique in the Saudi population.

The Correlation Between Clinical Phenotype and Genotype of Hereditary Spherocytosis

Objective: Hereditary spherocytosis (HS) is a common hereditary hemolytic disease. This study aimed to explore the correlation between the phenotype and mutant genotype of HS to improve the clinical understanding of HS. Methods: This study reported a case of spontaneous mutation of the ANK1 gene in HS, reviewed previous studies on the genotype-phenotype correlation of HS, statistically analyzed the main types of gene mutations in HS, and summarized the clinical data of patients. Results: This patient had clinical manifestations of anemia, splenomegaly, peripheral blood smear with increased spherocytosis, and bilirubin, confirmed as ANK1 gene mutant HS by gene detection. In addition, this study included 14 previous studies on genotype-phenotype correlation, collected data, and determined that the ANK1 and SPTB genes were the most common types of gene mutations in HS patients. The mutant HS of the ANK1 gene would lead to lower hemoglobin levels. Conclusion: The results of this study showed that ANK1 and SPTB were the most common types of gene mutations in HS patients. Compared with patients with the SPTB genotype HS, patients with ANK1 mutant HS had more severe extravascular hemolysis, and a higher proportion needed splenectomy in early childhood.

Case report: Genetic analysis of a novel intronic inversion variant in the SPTB gene associated with hereditary spherocytosis

Background: Hereditary spherocytosis (HS) is a congenital haemolytic anaemia attributed to dysregulation or abnormal quantities of erythrocyte membrane proteins. Currently, the most common erythrocytic gene, spectrin β (SPTB), variants are located in exons and give rise to mRNA defects. However, the genetic characteristics and pathogenic mechanisms of SPTB intronic variants are not completely understood. This study aimed to analyse a rare intronic inversion variant in the SPTB gene associated with HS, and explore the impact of the variant on SPTB mRNA splicing. Method: The clinical manifestations of the patient were summarised and analysed for spherocytosis phenotype diagnosis. The pathogenic variant was identified in the proband using targeted next-generation and Sanger sequencing. RNA sequencing was performed to analyse whether SPTB gene splicing and expression were affected. Results: Targeted next-generation sequencing identified a novel disease-associated intronic inversion variant of the SPTB gene in the proband. The inversion variant was located between intron 19 and 20, and contained the entire exon 20 and partial sequences of adjacent introns. Sanger sequencing confirmed that the intronic inversion variant only appeared in the genome of the proband, not in his parents. RNA sequencing revealed that the variant could result in the skipping of exon 20 and reduced expression of SPTB mRNA. Conclusion: This study identifies a rare intronic inversion variant in the SPTB gene associated with hereditary spherocytosis. The pathogenic variant can lead to exon 20 skipping and decreased SPTB gene expression. This finding has not been previously reported in any literature. This study can expand the intronic variant spectrum of the SPTB gene, deepen our understanding of HS pathogenesis, and contribute to the genetic diagnosis and clinical management of patients.

Potential Theranostic Roles of SLC4 Molecules in Human Diseases

The solute carrier family 4 (SLC4) is an important protein responsible for the transport of various ions across the cell membrane and mediating diverse physiological functions, such as the ion transporting function, protein-to-protein interactions, and molecular transduction. The deficiencies in SLC4 molecules may cause multisystem disease involving, particularly, the respiratory system, digestive, urinary, endocrine, hematopoietic, and central nervous systems. Currently, there are no effective strategies to treat these diseases. SLC4 proteins are also found to contribute to tumorigenesis and development, and some of them are regarded as therapeutic targets in quite a few clinical trials. This indicates that SLC4 proteins have potential clinical prospects. In view of their functional characteristics, there is a critical need to review the specific functions of bicarbonate transporters, their related diseases, and the involved pathological mechanisms. We summarize the diseases caused by the mutations in SLC4 family genes and briefly introduce the clinical manifestations of these diseases as well as the current treatment strategies. Additionally, we illustrate their roles in terms of the physiology and pathogenesis that has been currently researched, which might be the future therapeutic and diagnostic targets of diseases and a new direction for drug research and development.

Integrative preimplantation genetic testing analysis for a Chinese family with hereditary spherocytosis caused by a novel splicing variant of SPTB

Hereditary spherocytosis (HS), the most common inherited hemolytic anemia disorder, is characterized by osmotically fragile microspherocytic red cells with a reduced surface area on the peripheral blood smear. Pathogenic variants in five erythrocyte membrane structure-related genes ANK1 (Spherocytosis, type 1; MIM#182900), SPTB (Spherocytosis, type 2; MIM#616649), SPTA1 (Spherocytosis, type 3; MIM#270970), SLC4A1 (Spherocytosis, type 4; MIM#612653) and EPB42 (Spherocytosis, type 5; MIM#612690) have been confirmed to be related to HS. There have been many studies on the pathogenic variants and mechanisms of HS, however, studies on how to manage the transmission of HS to the next-generation have not been reported. In this study, we recruited a patient with HS. Targeted next-generation sequencing with a panel of 208 genes related to blood system diseases detected a novel heterozygous variant in the SPTB: c.300+2dup in the proband. Sanger sequencing of variant alleles and haplotype linkage analysis of single nucleotide polymorphism (SNP) based on next-generation sequencing were performed simultaneously. Five embryos were identified with one heterozygous and four not carrying the SPTB variant. Single-cell amplification and whole genome sequencing showed that three embryos had varying degrees of trisomy mosaicism. One of two normal embryos was transferred to the proband. Ultimately, a healthy boy was born, confirmed by noninvasive prenatal testing for monogenic conditions (NIPT-M) to be disease-free. This confirmed our successful application of PGT in preventing transmission of the pathogenic variant allele in the HS family.

Splenectomy improves erythrocyte functionality in spherocytosis based on septin abundance, but not maturation defects

Splenectomy improves the clinical parameters of patients with hereditary spherocytosis, but its potential benefit to red blood cell (RBC) functionality and the mechanism behind this benefit remain largely overlooked. Here, we compared 7 nonsplenectomized and 13 splenectomized patients with mutations in the β-spectrin or the ankyrin gene. We showed that hematological parameters, spherocyte abundance, osmotic fragility, intracellular calcium, and extracellular vesicle release were largely but not completely restored by splenectomy, whereas cryohemolysis was not. Affected RBCs exhibited decreases in β-spectrin and/or ankyrin contents and slight alterations in spectrin membrane distribution, depending on the mutation. These modifications were found in both splenectomized and nonsplenectomized patients and poorly correlated with RBC functionality alteration, suggesting additional impairments. Accordingly, we found an increased abundance of septins, small guanosine triphosphate-binding cytoskeletal proteins. Septins-2, -7, and -8 but not -11 were less abundant upon splenectomy and correlated with the disease severity. Septin-2 membrane association was confirmed by immunolabeling. Except for cryohemolysis, all parameters of RBC morphology and functionality correlated with septin abundance. The increased septin content might result from RBC maturation defects, as evidenced by (1) the decreased protein 4.2 and Rh-associated glycoprotein content in all patient RBCs, (2) increased endoplasmic reticulum remnants and endocytosis proteins in nonsplenectomized patients, and (3) increased lysosomal and mitochondrial remnants in splenectomized patients. Our study paves the way for a better understanding of the involvement of septins in RBC membrane biophysical properties. In addition, the lack of restoration of septin-independent cryohemolysis by splenectomy may call into question its recommendation in specific cases.

A de novo ANK1 mutation in a childhood hereditary spherocytosis: a case report

BACKGROUND

Due to the heterogeneity of the phenotype of Hereditary spherocytosis (HS) patients, some patients may have rare clinical complications such as biliary obstruction and ultra-high bilirubinemia.

CASE PRESENTATION

A 8-y-old boy presented to the emergency with complaints of anemia for 6 years and worsened abdominal pain and scleral yellowing of the skin for 2 days. Physical examination showed tenderness in the middle and upper abdomen and splenomegaly. Abdominal CT revealed biliary obstruction. Genetic analysis revealed a de novo mutation in the gene ANK1, HS with biliary obstruction was diagnosed. The surgery of bile duct exploration and T-tube drainage, and splenectomy were performed successively. This patient was followed up for 13 months after splenectomy, and his condition was stable.

CONCLUSION

The diagnosis of HS is not clinically difficult, and once a patient with HS is diagnosed, regular follow-up management and standardized treatment are required. Genetic testing is also needed to screen for other genetic disorders that may co-exist in patients with HS who do not have a good efficacy or who have a long-term chronic onset of jaundice.

Degradation of band3 and PRDX2 in erythrocytes during severe acute GVHD

We investigated the proteins of erythrocytes from stem cell transplantation patients and found decreased expression of band3 and C-terminal-truncated peroxiredoxin 2 (PRDX2) only during severe graft-versus-host disease (GVHD), using time-of-flight mass spectrometry (TOF-MS) analysis and Western blotting. During the same period, PRDX2 dimerization and calpain-1 activation were observed, indicating severe oxidative stress. We also found a putative cleavage site for calpain-1 in the C-terminal-truncated site of PRDX2. Decreased band3 expression impairs the plasticity and stability of erythrocytes, and C-terminal-truncated PRDX2 induces irreversible dysfunction of antioxidant activity. These effects may exacerbate microcirculation disorders and the progression of organ dysfunction.

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.

Clinical manifestations of adult hereditary spherocytosis with novel SPTB gene mutations and hyperjaundice: A case report

BACKGROUND

The aim of the present study was to enhance understanding of the diagnosis and treatment of atypical hereditary spherocytosis (HS), and to broaden the diagnostic thoughts of physicians for patients with jaundice.

CASE SUMMARY

A 28-year-old male presented with jaundice, bile duct stone, and splenomegaly, but without anemia. Other causes of jaundice were excluded, and gene sequencing revealed a novel heterozygous variant of c.1801C>T (p.Q601X) in exon 14 of the SPTB (NM_01355436) gene on chromosome 14 (chr14: 65260580) in the patient’s blood; the biological parents and child of the patient did not have similar variants. A splenectomy was performed on the patient and his bilirubin levels returned to normal after surgery. Thus, a novel gene variant causing HS was identified. This variant may result in the truncation of β-hemoglobin in the erythrocyte membrane, leading to loss of normal function, jaundice, and hemolytic anemia. The clinical manifestations of the patient were hyperjaundice and an absence of typical hemolysis during the course of the disease, which caused challenges for diagnosis by the clinicians.

CONCLUSION

Following a definitive diagnosis, genetic testing and response to treatment identified a gene variant site for a novel hemolytic anemia.

Clinical manifestations of 17 Chinese children with hereditary spherocytosis caused by novel mutations of the ANK1 gene and phenotypic analysis

Background: Hereditary spherocytosis (HS) is an autosomal dominant (AD) and autosomal recessive (AR) disorder that is mostly caused by mutations of the erythrocyte membrane-related gene ANK1. Methods: Clinical and genetic testing data of 17 HS children with ANK1 gene mutations were retrospectively collected. Clinical manifestations and phenotypic analysis of HS were summarized based on our experience and literature review. Results: A total of 17 mutations of the ANK1 gene were identified from 17 probands (12 sporadic cases and five familial cases), including 15 novel mutations and two previously reported ones. Among the 15 novel variants of ANK1, there were four non-sense mutations, four frameshift mutations, three splicing mutations, three missense mutations and one in-frame deletion of three amino acids. In the present study, HS patients with mutations in membrane binding domains had significantly lower hemoglobin (Hb) levels and higher total bilirubin (T-Bil) levels than those with mutations in regulatory domains. After reviewing and analyzing all available published reports of Chinese HS patients carrying ANK1 mutations in PubMed and Chinese journals, there were no significant differences in Hb, Ret and T-Bil between different mutation types or mutation regions. Conclusion: Mutations of the ANK1 can be inherited or de novo. Clinical manifestations of HS in children caused by ANK1 mutations are similar to those of other types of hemolytic anemia. Our report expands the mutation spectrum of HS, thus providing references for clinical management and genetic counseling of HS.

A large family of hereditary spherocytosis and a rare case of hereditary elliptocytosis with a novel SPTA1 mutation underdiagnosed in Taiwan: A case report and literature review

RATIONALE

Hereditary spherocytosis (HS) has a defect in the vertically connected proteins on the cell membrane of red blood cells (RBC). Hereditary elliptocytosis (HE) has a defect in proteins that connect the cell membrane horizontally. We reported two families of RBC membrane disorders in Taiwanese, one was HS and the other was HE.

PATIENT CONCERNS

Case 1. A 19-year-old male student with chronic jaundice and splenomegaly. His mother, maternal uncle, grandmother, and many members of older generations also had splenomegaly and underwent splenectomy. Case 2. A 40-year-old man has experienced pallor and jaundice since the age of 20 and was found to have splenomegaly, and gall bladder stones in the older age. His younger sister also had pallor and jaundice for a long time.

DIAGNOSES

In case 1, a peripheral blood smear showed 20% spherocytes. Eosin-5-maleimide labeled RBC by flow cytometry showed a result of 30.6 MCF (cutoff value: 45.5 MCF). He was diagnosed with HS. The gene analysis identified a heterozygous mutation with c.166A > G (p.Lys56Glu) in the SLC4A1 gene in this proband, his mother, and maternal uncle. In case 2, more than 40% of ellipsoid RBC present in the peripheral blood smear. He was diagnosed with HE. Genetic analysis of the SPTA1 gene identified a novel heterozygous exon2, c.86A > C, p.Gln29Prol mutation.

INTERVENTIONS

The two patients had compensated anemia, clinical follow-up instead of splenectomy was done.

OUTCOMES

The two patients had normal daily activities and lives.

LESSONS

We reported two Taiwanese families, one was hereditary spherocytosis affected by a heterozygous mutation with c.166A > G (p.Lys56Glu) in SLC4A1, and the other was hereditary elliptocytosis caused by a novel heterozygous SPTA1 gene mutation, c. 86A > C, p.Gln29Prol. These 2 seemingly common hereditary red blood cell membrane protein defects induced by hemolysis are usually underdiagnosed or misdiagnosed.

Spherocytosis-Related L1340P Mutation in Ankyrin Affects Its Interactions with Spectrin

Previously, we reported a new missense mutation in the ANK1 gene that correlated with the hereditary spherocytosis phenotype. This mutation, resulting in L1340P substitution (HGMD CM149731), likely leads to the changes in the conformation of the ankyrin ZZUD domain important for ankyrin binding to spectrin. Here, we report the molecular and physiological effects of this mutation. First, we assessed the binding activity of human β-spectrin to the mutated ZZUDL1340P domain of ankyrin using two different experimental approaches-the study of association and dissociation responses of the spectrin-ankyrin binding domain and a sedimentation assay. In addition, we documented the changes in morphology caused by the overexpressed ankyrin ZZUD domain in human cell models. Our results prove the key role of the L1340 aa residue for the correct alignment of the ZZUD domain of ankyrin, which results in binding the latter with spectrin within the erythrocyte membrane. Replacing L1340 with a proline residue disrupts the spectrin-binding activity of ankyrin.

Congenital Disorders of Red Blood Cells

See Bonus NeoBriefs videos and downloadable teaching slides Understanding the physiologic process of red blood cell development in utero and subsequent erythropoiesis in the neonate is crucial as this determines red blood cell structure and therefore function, which is vital to neonatal health. Infants frequently experience anemia, and special consideration must be given to the evaluation of these infants to determine the correct etiology. Traditionally, anemia is conceptualized in terms of inadequate red blood cell production, increased red blood cell destruction, or whole blood loss. This framework translates well to inherited red blood cell defects, which include genetic abnormalities in bone marrow productivity or structure of the red blood cell membrane, enzymes, or hemoglobin. This article highlights fetal and neonatal erythropoiesis and the underlying etiologies of the inherited red blood cell disorders, as well as reviews the appropriate diagnostic evaluation and next steps in management. It is imperative that neonatal clinicians remain informed about these disorders to enable early recognition and treatment, and ultimately to improve outcomes in affected infants.

[Congenital hemolytic anemias due to erythrocyte membrane and enzyme defects]

Erythrocyte membrane and enzyme defects are the most common cause of congenital hemolytic anemias in the Central European population. Diagnostics include erythrocyte morphology, special biochemical tests such as osmotic fragility (AGLT) and EMA. For enzymopenic hemolytic anemias, cost-effective biochemical analysis remains the gold standard, supplemented by molecular genetic diagnostics when appropriate. Therapeutically, near complete splenectomy reduces hemolysis significantly for spherocytosis. The residual spleen at least provides a considerable phagocytic function and better response to immunisation and by inference possibly better protection against severe post-splenectomy infection. For pyruvate kinase deficiency, which is not so rare, a new molecular therapy (Mitapivat) is currently being introduced. In G6PD deficiency, there are very few drugs that cause hemolytic crisis. Sudden onset of hemoglobinuria is an early important hallmark of severe hemolytic crisis in G6PD deficiency and these patients should be hospitalized. Aplastic crises in the setting of parvovirus B19 infection occur in all congenital hemolytic anemias. Transfusion is not preventable in most cases. Iron-excreting treatment is required in the rare patients in need of chronic transfusion.

Use of blood and its components in the treatment of anaemia in children

Blood transfusion is a well-established treatment for anaemia. Herein, blood and its components are transfused to replenish circulating blood volume, maintain the oxygen capacity of the blood and normalise the function of the coagulation system. Anaemia treatment by blood transfusions is a great challenge, especially with reference to paediatric patients. Blood is irreplaceable in a life-threatening situation, but it has its own side effects, just like all applied pharmacological products. Hence, it is extremely important to carefully select donors and utilise blood components according to the patient’s individual needs. Children represent a group that requires specific criteria to be met, mainly because of the fact that their physiological and haematological systems differ from those of adults. The most common types of anaemia seen in children are deficiency anaemias such as iron-deficiency anaemia, while less common are vitamin B12 deficiency anaemia or folate deficiency anaemia. Secondary anaemia is also relatively frequent in chronic diseases, among others, immunological or infectious, as well as renal, liver, endocrine and neoplastic diseases. Anaemia due to blood loss is also included in this group. Furthermore, some anaemias, such as aplastic anaemia (due to impaired erythrocyte production) and haemolytic anaemia (due to excessive destruction of red blood cells) may be congenital or acquired. Before deciding to implement blood therapy, the patient’s clinical condition or the different haematological, biochemical and immunological parameters at different stages of life should be considered. Since each transfusion may result in a variety of post-transfusion reactions, immunisation or transmission of infectious diseases, the decision to transfuse blood or blood components should be taken only when the patient cannot be treated effectively by any other means and the expected benefits of the transfusion outweigh the risks associated with possible complications. Considering the recipients’ low blood volume, low metabolic efficiency, higher haematocrit levels than in adults and immature immune system, products for these patients should be prepared in a special way. These components must ensure minimal risk of metabolic and haemostatic disorders. The collection of these products, as well as their preparation, storage and transfusion, should be carried out in accordance with current legislation.

Targeted next-generation sequencing identifies a novel nonsense mutation in ANK1 for hereditary spherocytosis: A case report

BACKGROUND

Hereditary spherocytosis (HS) is characterized by anemia, jaundice, splenomegaly, and cholelithiasis, and is caused by abnormal genes encoding red blood cell membrane components. The most common mutations found in HS are in the ANK1 gene.

CASE SUMMARY

A 4-mo-old girl was admitted to our hospital with pallor that had lasted for more than 2 mo. She presented with jaundice, anemia and splenomegaly. A heterozygous mutation of ANK1 (exon23: c.G2467T:p.E823X) was identified, and the mutation was determined to be autosomal dominant. This mutation is linked to the relatively serious anemia she had after birth; this anemia improved with age.

CONCLUSION

The utilization of next-generation sequencing may assist with the accurate diagnosis of HS, especially in atypical cases.

Spectrins and human diseases

Spectrin, as one of the major components of a plasma membrane-associated cytoskeleton, is a cytoskeletal protein composed of the modular structure of α and β subunits. The spectrin-based skeleton is essential for preserving the integrity and mechanical characteristics of the cell membrane. Moreover, spectrin regulates a variety of cell processes including cell apoptosis, cell adhesion, cell spreading, and cell cycle. Dysfunction of spectrins is implicated in various human diseases including hemolytic anemia, neurodegenerative diseases, ataxia, heart diseases, and cancers. Here, we briefly discuss spectrins function as well as the clinical manifestations and currently known molecular mechanisms of human diseases related to spectrins, highlighting that strategies for targeting regulation of spectrins function may provide new avenues for therapeutic intervention for these diseases.

Effects of SPTA1 Gene Variants on the Hematological Phenotype of Mexican Patients with Hereditary Spherocytosis

Introduction: Hereditary spherocytosis (HS) is a common hereditary hemolytic anemia characterized by chronic hemolysis, increased indirect serum bilirubin, the presence of reticulocytes and spherocytes in blood smears, and great heterogeneity at the clinical, biochemical, and molecular levels. The molecular pathology of HS includes genetic variants at five genes: ANK1, EPB42, SLC4A1, SPTA1, and SPTB. Alpha spectrin (SPTA1) deficiency is the second leading cause of HS in Mexican patients. Aim: To assess the effects of five SPTA1 variants on the hematological phenotype of Mexican patients with HS. Materials and Methods: This study included a retrospective cohort of 227 biologically unrelated patients with HS. Variants c.4339-99C>T and c.6531-12C>T in SPTA1 were identified by the amplification-refractory mutation system polymerase chain reaction (ARMS-PCR), and variants c.5572C>T, c.5992C>G, and c.6794T>C were identified by quantitive Real Time-Polymerase Chain Reaction (qRT-PCR) allelic discrimination. Risk tests were performed for each variant with respect to HS clinical severity. Results: The SPTA1 c.5992C>G variant showed association with moderately severe HS (p = 0.006, odds ratio = 5.67, confidence interval95% = 1.6-19.9); the risk increased when the variant was in compound heterozygosity with αLELY and c.6794T>C. Lower hematological levels were observed in simple αLely (c.5572C>T and c.6531-12C>T), and c.5992C>G heterozygotes (red blood cell [RBC] p = 0.028 and 0.010; hemoglobin [Hb] p = 0.030 and 0.002; packed cell volume [PCV] p = 0.034 and 0.002 respectively), and in c.5992C>G+c.6794T>C compound heterozygotes (RBC p = 0.043; Hb p = 0.033; PCV p = 0.043). Additional genetic traits were observed: 15% had HS+Gilbert syndrome and 13% HS+thalassemia. Conclusion: Although most of the studied variants are considered benign, we observed significant associations with phenotypic severity. Therefore, we recommend the inclusion of these variants in molecular screening for HS.

Band 3/anion exchanger 1/solute carrier family 4 member 1 expression as determinant of cellular sensitivity to selenite exposure

Selenium is a chalcogen element that is essential in animals, but is highly toxic when ingested above the nutritional requirement. Selenite is used as a supplement in patients receiving total parenteral nutrition. However, the therapeutic and toxic doses of selenite are separated by a narrow range. This ambivalent character of selenite implies the presence of cellular mechanisms that precisely control selenite homeostasis. Here, we investigated mechanisms that determine cellular susceptibility to selenite exposure. The resistance to selenite exposure was significantly different among cell lines. We determined the expression levels of TPMT (thiopurine S-methyltransferase) and SLC4A1 (solute carrier family 4 member 1), which encode selenium methyltransferase and selenite transporter, respectively. We also examined the effect of inhibition of Band 3 protein activity, which is encoded by SLC4A1, on the cellular sensitivity to selenite. The data suggest that the expression level of SLC4A1 is the determinant of cellular sensitivity to selenite.

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TPMT expression level was not correlated with susceptibility to selenite.

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SLC4A1 expression level was correlated with sensitivity to selenite.

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Inhibition of SLC4A1 protein improved cellular survival after selenite exposure.

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Incorporation, but not methylation, was important for cell-specific selenite sensitivity.

Clinical Features and Outcome of Children With Hereditary Spherocytosis

OBJECTIVE

The aim of this study was to evaluate the demographics, clinical, and laboratory findings and treatment responses of patients with hereditary spherocytosis (HS).

MATERIALS AND METHODS

Data of children with HS were examined. Diagnosis was based on clinical history, physical examination, family history, presence of spherocytes on peripheral blood smear, and osmotic fragility test.

RESULTS

A total of 101 patients were included. The median (range) age at diagnosis was 38.0 (1 to 188) months. Mild, moderate, and severe forms of HS were present in 29 (28.7%), 15 (14.9%), and 57 (56.4%) patients, respectively. Family history was available in 73 patients and 56 of these (76.7%) had a positive family history for HS. Forty-five (44.5%) patients needed regular transfusions and all of these had severe disease. Although most patients did not require transfusion postsplenectomy, 2 of 45 (4.4%) patients continued to require transfusion. Transfusion dependence was significantly (P<0.001) higher in patients with severe spherocytosis.

CONCLUSIONS

In HS, splenomegaly, pallor, and jaundice are the most common clinical features. Splenectomy dramatically reduces hemolysis in most cases and virtually abolishes further requirement for transfusion.

Hereditary Spherocytosis With Liver Transplantation After Cirrhosis: A Case Report

The clinical manifestations of hereditary spherocytosis are similar to those of various hemolytic anemias, which causes hereditary spherocytosis to be difficult to diagnose clinically. In this case, we obtained the peripheral blood of a patient and family members, and through a whole exome test of the 6,297 genetic phenotypes confirmed by OMIM, we found a heterozygous nonsense mutation (c.4117C>T, P.Q1373X) in the SPTB gene. Combined with the patient's clinical data, the diagnosis was hereditary spherocytosis. Compared with the public population sequence database, the mutation was found to be unique. Through protein structure prediction analysis and literature studies, we found that the mutation may cause SPTB mRNA instability, resulting in insufficient spectrin protein synthesis and affecting the integrity and flexibility of the red blood cell membrane skeleton. This case report found that SPTB gene mutations may cause liver dysfunction and cirrhosis in addition to hereditary spherocytosis, and this finding expands the phenotypic spectrum of SPTB. This study confirmed that NGS can be used to diagnose hereditary spherocytosis. Identifying mutated genes can not only accurately treat diseases, but also avoid potential genetic risks and improve prenatal and postnatal care.

A novel SPTB mutation causes hereditary spherocytosis via loss-of-function of β-spectrin

Hereditary spherocytosis (HS) is the most frequently observed chronic non-immune hemolytic disorder caused by altered red cell membrane function. SPTB gene mutation is one of the most common causes of HS, but pathogenicity analyses and pathogenesis research on these mutations have not been widely conducted. In this study, a novel heterozygous mutation of the SPTB gene (c.1509_1518del; p.K503Nfs*67) was identified in a Chinese family with HS by whole-exome sequencing (WES) and was then confirmed by Sanger sequencing. Next, the pathogenicity and pathogenesis of this mutation were studied using peripheral blood. We found that this mutation disrupted the synthesis and localization of β-spectrin and weakened the interaction between β-spectrin and ankyrin, which may be caused by the nonsense-mediated mRNA degradation pathway. These changes lead to the transformation of discoid erythrocytes into spherocytes, resulting in hemolytic anemia. Therefore, we classified this novel mutation as a pathogenic mutation leading to loss-of-function of β-spectrin. It would be insightful to perform the same mutation test and to provide genetic counseling to other relatives of the proband. Our study increases the current understanding of the molecular mechanisms related to mutations in SPTB.

The diagnostic protocol for hereditary spherocytosis-2021 update

Background

Hereditary spherocytosis (HS), a commonly encountered hereditary hemolytic disease, is mostly inherited in an autosomal dominant manner. The clinical manifestations in patients with HS show obvious heterogeneity. Moreover, the sensitivity or specificity of some HS diagnostic tests are not ideal and may easily result in misdiagnosis or missed diagnosis in some patients. The objective of this study was to propose a simple and practical diagnostic protocol, which can contribute to the diagnosis of HS and its differential diagnosis with different types of hemolytic anemia such as thalassemia (THAL), autoimmune hemolytic anemia (AIHA), and glucose‐6‐phosphate dehydrogenase (G6PD) deficiency, thus, to provide an alternative simple and reliable method for better clinical diagnosis of HS.

Methods

Through combing our research with existing experimental technologies and studies, we propose a simple and practical protocol for HS diagnosis, which will help clinicians to improve HS diagnosis.

Results

Compared with the existing HS diagnostic protocols, the HS diagnostic protocol we proposed is simpler. In this new protocol, some experimental tests with ideal diagnostic efficiency are added, such as mean reticulocyte volume (MRV), mean sphered cell volume (MSCV), mean corpuscular volume (MCV), in combination with the observation of clinical manifestations, family investigation, routine tests for hemolytic anemia, genetic testing, and other screening tests.

Conclusion

The HS diagnostic protocol we proposed could improve the clinical practice and efficiency of HS diagnosis.

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.

Reduced off-target effect of NG-BE4max by using NG-HiFi system

Recently, a rationally engineered SpCas9 variant (SpCas9-NG) that can recognize a minimal NG protospacer adjacent motif (PAM) was reported to expand the targeting scope in genome editing. However, increased genome-wide off-target mutations with this variant compared with SpCas9 were reported in previous studies. In addition, lower base editing frequencies and higher unintended off-target mutations were also found in Hoxc13-ablated rabbits generated by NG-BE4max in our study. Here, a high-fidelity base editor, NG-HiFi, in comparison to NG-BE4max, showed retention of on-target activity while exhibiting significantly decreased off-target activity in Hoxc13-ablated rabbits. Collectively, the improved specificity and reduced off-target effect of SpCas9-NG assisted in cytidine base editing with the NG-HiFi system, providing a promising tool to precisely model human diseases in rabbits.

Distal Renal Tubular Acidosis in an Iranian Patient with Hereditary Spherocytosis

Background:

Hereditary spherocytosis and hereditary dRTA are associated with mutations in the SLC4A1 gene encoding the AE1. In this study, some patients with clinical evidence of congenital HS and renal symptoms were investigated.

Methods:

Twelve patients with congenital HS and renal symptoms were recruited from Ali-Asghar Children’s Hospital (Tehran, Iran). A patient suspected of having dRTA was examined using WES method, followed by Sanger sequencing.

Results:

One patient (HS03) showed severe failure to thrive, short stature, frequent urinary infection, and weakness. A homozygote (rs571376371 for c.2494C>T; p.Arg832Cys) and a heterozygote (rs377051298 for c.466C>T; p.Arg156Trp) missense variant were identified in the SLC4A1 and SPTA1 genes, respectively. The compound heterozygous mutations manifested as idRTA and severe HS in patient HS03.

Conclusion:

Our observations, for the first time, revealed clinical and genetic characteristics of idRTA and severe HS in an Iranian patient HS03.

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.

Preliminary Study on the Clinical and Genetic Characteristics of Hereditary Spherocytosis in 15 Chinese Children

Objective

To investigate the clinical and genetic characteristics of hereditary spherocythemia (HS) in Chinese children, and to analyze the potential genotypic/phenotypic associations.

Methods

The clinical data and gene test results of children with HS were collected. All patients were diagnosed by gene test results, and the laboratory results were obtained before splenectomy. The data of red blood cell (RBC), hemoglobin (HB), mean red blood cell volume (MCV), mean red blood cell hemoglobin (MCH), mean red blood cell hemoglobin concentration (MCHC), and hematocrit (HCT) were statistically analyzed according to different mutation genes. Statistical methods for comparison between groups Mann–Whitney test analysis, two-terminal p < 0.05 was considered significant difference.

Results

A total of 15 children were enrolled in our hospital, and 14 variants were found (nine variants have not been reported before), including 10 ANK1 mutations (seven ANK1 truncated mutations) and five SPTB mutations. Patients with ANK1 mutations had more severe anemia than those with SPTB mutations (significantly lower RBC, HB, MCHC, and HCT).

Conclusion

This is one of the few studies on the genetic and clinical characteristics of children with HS in China. This study identified the unique genetic and clinical characteristics of Chinese children with HS and analyzed the pathogenic genotype–phenotypic association. The results confirmed that the anemia degree of HS patients caused by ANK1 was more serious than that of patients with SPTB deficiency. However, further study of the correlation between genotype and phenotype requires a larger sample size.

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-021-00912-3.

Clinical manifestation and phenotypic analysis of novel gene mutation in 28 Chinese children with hereditary spherocytosis

Purpose

Objective to summarize the clinical features and laboratory findings of 28 Chinese children with hereditary spherocytosis (HS), and analyze these mutations.

Method

Collected and analyzed the clinical data of all children and their parents, and completed the relevant laboratory examinations of all children. Analyzed the sequence of related genes by second‐generation sequencing technology, and verified the suspected mutations by Sanger sequencing method. Analyzed all biological information using the Single Nucleotide Polymorphism database, the 1000 Human Genome Project, and the Exosome Aggregation Consortium.

Result

New mutations were detected in the HS coding region of 28 children. Among them, there were 13 cases (46.4%) with ANK1 mutation, 10 cases (35.7%) with SPTB mutation, three cases (10.7%) with SLC4A1 mutation, and two cases (7.2%) with SPTA1 mutation. All mutations cause amino acid changes in the coding gene, as well as subsequent changes in protein structure or loss of function.

Conclusion

All the newly discovered gene coding region mutation sites detected are the suspected pathogenic causes of the 28 Chinese children. At the same time, the second‐generation gene sequencing technology is an effective means to diagnose HS. Different mutation types and different mutation regions have no significant correlation with the severity of anemia. The novel gene mutation sites in 28 children studied in this paper have not yet been included in the human genome database, dbSNP (v138), or ExAC database. The new gene mutations found in HS children can provide a theoretical basis for further exploring the genetic causes of HS in Chinese children.

Hereditary spherocytosis overlooked for 7 years in a pediatric patient with β-thalassemia trait and novel compound heterozygous mutations of SPTA1 gene

Objectives: We aimed to determine the clinical and genetic characteristics of a boy diagnosed with the β-thalassemia trait. He also had hereditary spherocytosis (HS) that had been overlooked for 7 years. Methods: Blood samples collected from the proband and his family were assessed by laboratory tests, and next-generation sequencing (NGS) and Sanger sequencing. Results: The β-thalassemia trait was complicated with HS in the proband. Compound heterozygous mutations of the Spectrin Alpha, Erythrocytic 1 (SPTA1) gene, c.83G > A and c.190G > A in the proband were inherited from his mother and father, respectively, and he also had the heterozygous c.126_129delCTTT mutation in the Hemoglobin Subunit Beta (HBB) gene. The c.190G > A mutation has not yet been added to the Human Gene Mutation Database (HGMD®). The heterozygous HBB c.126_129delCTTT mutation was inherited from his mother, and his older brother also had this mutation. Conclusion: Compared with other patients with either HS or β-thalassemia, this proband with both HS and the β-thalassemia trait had very complicated laboratory findings, which resulted in HS being overlooked for 7 years. Genetic testing is invaluable for the differential diagnosis of hereditary anemias with overlapping clinical features.

Case Report: Signal Transducer and Activator of Transcription 3 Gain-of-Function and Spectrin Deficiency: A Life-Threatening Case of Severe Hemolytic Anemia

STAT3 gain-of-function (GOF) mutations can be responsible for an incomplete phenotype mainly characterized by hematological autoimmunity, even in the absence of other organ autoimmunity, growth impairment, or severe infections. We hereby report a case with an incomplete form of STAT3 GOF intensified by a concomitant hereditary hematological disease, which misleads the diagnosis. The patient presented with lymphadenopathy, splenomegaly, hypogammaglobulinemia, and severe autoimmune hemolytic anemia (AIHA) with critical complications, including stroke. A Primary Immune Regulatory Disorders (PIRD) was suspected, and molecular analysis revealed a de novo STAT3 gain-of-function mutation. The response to multiple immune suppressive treatments was ineffective, and further investigations revealed a spectrin deficiency. Ultimately, hematopoietic stem cell transplantation from a matched unrelated donor was able to cure the patient. Our case shows an atypical presentation of STAT3 GOF associated with hereditary spherocytosis, and how achievement of a good long-term outcome depends on a strict clinical and laboratory monitoring, as well as on prompt therapeutic intervention.

Novel nonsense mutation p. Gln264Ter in the ANK1 confirms causative role for hereditary spherocytosis: a case report

Background

Hereditary spherocytosis (HS) is the most common haemolytic anaemia caused by congenital membrane defects of red blood cells. The name derives from the presence of spherical red blood cells in the peripheral blood. Clinical manifestations of HS are anaemia, haemolytic jaundice, and large spleen, and infection can worsen the condition, often with cholelithiasis. HS is mainly caused by abnormal functions of the products of six genes. Splenectomy is the main treatment for HS.

Case presentation

Half a day after birth, the proband exhibited HS-related symptoms, with progressive aggravation. Routine examination in the outpatient department showed an increase in white blood cells and a decrease in red blood cells. His mother had HS and a partial splenectomy. We suspected that the infant might also have HS. Genomic DNA samples were extracted from the three members of the HS trio pedigree, and genomic whole-exome sequencing (WES) was performed. The three DNA samples were amplified by polymerase chain reaction (PCR), followed by Sanger sequencing to identify mutation sites. A novel nonsense heterozygous mutation, c.790C > T (p. Gln264Ter), in the ANK1 gene, which causes premature termination of translation, was found in this Chinese family with autosomal dominant HS.

Conclusions

This de novo nonsense mutation can cause the onset of HS in early childhood, with severe symptoms. Expanding the ANK1 genotype mutation spectrum will lay a foundation for the further application of mutation screening in genetic counselling.

TK6 genome profile compared with WIL2-NS: Reference data to improve the reproducibility of genotoxicity studies

The TK6 cell line has been widely used for genotoxicity screening by taking advantage of the TK1 mutations. A number of publications have employed TK6 as a tool for the assay; however, its characterization is limited. Because genomes of cell lines are often changed during cell culture, differences in TK6 genomes could be observed between laboratories, which would cause potential problems with reproducibility using TK6. In this study, TK6(IVGT) (JCRB1435), registered with the JCRB Cell Bank as the standard for TK6, has been characterized by karyotyping, SNP microarray and targeted sequencing, and were then compared to WIL2-NS (JCRB9063), a subline derived from a common ancestor with TK6. Changes at the chromosome level were quantitatively assessed by the microarray data, which were shown by DNA sizes and Scales of Genomic Alterations (SGA). An extinct common ancestral cell line, WI-L2 originated from hereditary spherocytosis, has been extrapolated from analysis of genomic signatures shared between TK6 and WIL2-NS, revealing a point mutation in SPTA1, related to the disease. DNA size is calculated to be 102.6 %, 103.1 % and 103.9 % for WI-L2, TK6(IVGT) and WIL2-NS respectively, with the reference values of a normal diploid genome, and each genome shows SGA of 2.8 %, 4.5 % and 4.2 % respectively. Differences between TK6(IVGT) and WIL2-NS are due to regions and sizes of gains, implying that genomes of both cells tend to increase their DNA size independently. Our data provide fundamental genomic features of TK6 and serve as a reference profile of the standardized TK6 cell line, which leads to an increase in robustness of assays using the TK6 cells.

A novel SPTB gene mutation in neonatal hereditary spherocytosis: A case report

The aim of the present study was to enhance the understanding of the diagnosis and treatment of neonatal hereditary spherocytosis (HS). Gene sequencing and analysis was performed for the crucial splicing signals on the exons and introns of the 302 known pathogenic genes [including ANK1, SPTAN1, SPTA1, EPB42, SLC4A1, and SPTB] that are associated with this genetic deficiency of erythrocytes. A 26-day-old female presented with jaundice, anemia, an increased count in peripheral blood reticulocyte and spherocytes and a positive acidified glycerol hemolysis test. Gene sequencing revealed a novel mutation of c.3737delA (p.Lys1246fs) in the exon 16 of SPTB (14q23|NM_000347.5) gene in the patient and her father. The mutation was a frame-shifting mutation, which may result in the truncation of β-haemoglobin in the erythrocyte membrane can lead to loss of normal function, leading to the occurrence of diseases, including jaundice and hemolytic anemia. For neonates with jaundice and anemia, family history, erythrocyte index and peripheral blood smear findings have been indicated to contribute to the diagnosis of HS. In the current study, gene sequencing was indicated to be helpful for the diagnosis of HS. A novel mutation of SPTB gene was identified, which may be pathogenic via modulating the activity of β-spectrin in the erythrocyte membrane.

Genetic and Clinical Characteristics of Patients With Hereditary Spherocytosis in Hubei Province of China

Hereditary spherocytosis (HS) is an inherited disorder characterized by anemia, splenomegaly, and spherical-shaped erythrocytes, caused by mutations in erythrocyte membrane Protein Genes (ANK1, SPTB, SLC4A1, SPTA1, and EPB42). We investigated molecular spectrum and genotype-phenotype correlation in HS patients in Hubei province, central China. Twenty-three patients with HS were included. A next-generation sequencing (NGS) panel targeting ANK1, SPTB, SLC4A1, SPTA1, and EPB42 genes was used to screen potential variants. Sanger sequencing was applied to validate variants. Of the twenty-three patients, thirteen patients carried ANK1 variants, and ten patients harbored SPTB variants, including ten non-sense, six indel, four splice site, one start-loss, and one missense variant. Four out of twenty-two variants in our study were known, and eighteen variants were novel. Most ANK1 and SPTB variants were indel (5/12) or non-sense (7/10), respectively. Family member analysis in thirteen families showed that six variants were de novo. Variable expressivities were observed in a pair of twins with ANK1 c.341C > T variant, and two unrelated patients both carried ANK1 c.2T > A variant. Genotype-phenotype analysis found no significant difference between ANK1 and SPTB regarding the levels of Hb, RBC, MCV, MCH, and MCHC. However, variants in the ANK1 death domain were associated with lower levels of MCV and MCH compared to other ANK1 domains. In conclusion, NGS is a fast way to provide a molecular HS diagnosis. We also identified unique genetic and clinical characteristics of patients with HS in Hubei Province, China. However, a large sample size is needed to further investigate the genotype-phenotype correlation.

SPTB related spherocytosis in a three-generation family presenting with kidney failure in adulthood due to co-occurrence of UMOD disease causing variant

BACKGROUND

Hereditary spherocytosis is clinically and genetically heterogeneous disorder and its clinical characteristics are spherocytosis, anaemia, jaundice and splenomegaly. The aetiology is associated to the genes encoding proteins involved in the interaction between the erythrocyte membrane and the lipid bilayer. Causative variants in βI-spectrin (SPTB) gene presenting as mild to moderately severe disease are responsible for approximately 25% cases in the USA and Europe. Among kidney disease, isolated cases of nephrotic syndrome due to membranoproliferative glomerulonephritis and macroscopic haematuria with proteinuria due to IgA nephropathy were previously reported in patients with SPTB deficiency.

OBJECTIVE

Seven patients from the same family with spherocytosis were evaluated to assess the kidney failure presented in all affected adult patients.

METHODS

Clinical, radiological and laboratory investigations were issued to evaluate the spherocytosis and kidney disease. In selected patients, we also performed genetics testing with next generation sequencing of genes related to hereditary spherocytosis, inherited glomerular disorders and tubulo-interstitial kidney disease.

RESULTS

Among the family members with spherocytosis, two adults had end-stage kidney disease and one chronic kidney disease stage 4 with unspecific histopathological findings of interstitial fibrosis/tubular atrophy and glomerulosclerosis. At the time, there were no signs of kidney disease present in four paediatric patients. Novel nonsense variant in SPTB gene (NM_001024858; c.4796G>A; p.Trp1599Ter) was detected in all family members with spherocytosis and was predicted to be disease causing. Furthermore, all adult patients with kidney failure and two paediatric cousins of the index patients were heterozygous for the UMOD gene variant (NM_003361.3:c.552G>C, NP_003352.2:p.Trp184Cys) previously reported in patients with tubulo-interstitial kidney disease. UMOD variant was not present in the index patients.

CONCLUSIONS

The co-occurrence of any two rare inherited disorders is extremely rare, while to our knowledge the co-occurrence of genetically confirmed HS and autosomal dominant tubulo-interstitial kidney disease (ADTKD) has previously not been reported. It is not possibly to evaluate whether the haemolytic crises due to HS are influencing the progression of the UMOD related renal disease, since the UMOD related ADTKD characteristics in general and in here presented family are extremely variable. Nevertheless, the observed kidney disease in the family is warranting the regular nephrological examinations in UMOD positive paediatric patients in the family in order to recognise hyperuricemia and treat it as early as possible. This is emphasising the importance of serum uric acid detection in routine laboratory screening of paediatric patients in order to identify early signs of tubular injury indicating possible ADTKD.

Deciphering molecular heterogeneity of Indian families with hereditary spherocytosis using targeted next-generation sequencing: First South Asian study

Defects in various erythrocyte membrane proteins genes (ankyrin, band-3, β- and α-spectrin and protein 4·2) can cause hereditary spherocytosis (HS). This molecular heterogeneity of HS, together with co-inherited genetic modifiers, results in marked phenotypic variability among patients. We studied the molecular spectrum and genotype-phenotype correlations in 73 families (with 113 patients) with HS. Deleterious variants including nonsense (42%), deletions (18%), splice site (20%), missense (10%) and duplication/insertion (10%) were found in 47 patients. The variants detected included sporadic and dominantly-inherited defects in ANK1 (53·2%), SPTB (36·2%) and SLC4A1 (4·2%). Compound heterozygous variants in SPTA1 (6·4%) showed autosomal recessive inheritance. Alpha-spectrin variants were associated with severe anaemia and splenectomy alleviated symptoms. Co-inherited glucose-6-phosphate dehydrogenase (G6PD) deficiency was found in 15%. G6PD variants (n = 5) led to greater transfusion requirements (1-8 times) in males with HS. Homozygosity (41%) for the promoter variant of UGT1A1 (Gilbert syndrome) led to a significantly higher mean bilirubin level (126·54 µmol/l) with a higher frequency of cholelithiasis (30%) (P < 0·001). This first-ever south Asian study on the molecular spectrum of HS found ANK1 and SPTB genes variants to be the commonest with inheritance being sporadic/dominant. Next-generation sequencing provided a relatively sensitive and rapid tool for molecular diagnosis with a diagnostic yield of 64·4%.

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.