Applications of Flow Cytometry in Diagnosis and Evaluation of Red Blood Cell Disorders.

Clinical flow cytometry plays a vital role in the diagnosis and monitoring of various red blood cell disorders. The high throughput, precision, and automation potential of this technique allows for cost-effective and timely analysis compared to older and more manual test methods. Flow cytometric analysis serves as the gold standard diagnostic method for multiple hematological disorders, especially in clinical scenarios where an assay needs to have high sensitivity, high specificity, and a short turnaround time. In this review, we discuss the role of flow cytometric analysis in paroxysmal nocturnal hemoglobinuria, fetal-maternal hemorrhage, and hereditary spherocytosis.

A novel variant in the SPTB gene underlying hereditary spherocytosis and a literature review of previous variants.

BACKGROUND: Hereditary spherocytosis (HS, MIM#612641) is one of the most common hereditary hemolytic disorders. This study aimed to confirm a novel variant's pathogenicity and reveal a patient's genetic etiology. METHODS: The clinical data of a patient with HS who underwent genetic sequencing at the Children's Hospital of Chongqing Medical University were reviewed retrospectively. In silico prediction and in vitro minigene splicing reporter system were then conducted on the detected variant to analyze its intramolecular impact. A summary of the literature related to HS due to SPTB gene variants was also presented. RESULTS: A novel variant (c.301-2 A > G) in the SPTB gene (NM_001024858.4) was identified in the proband. Using Sanger sequencing, we conclusively confirmed that the inheritance of the variant could not be traced to the biological parents. The in vitro minigene assay revealed three different transcripts derived from the c.301-2 A > G variant: r.301_474del, r.301_306delCCAAAG, and r.301-1_301-57ins. Through a literature review, patients with HS who had been genotypically validated were summarized and the SPTB gene variant profile was mapped. CONCLUSION: We identified a splicing variant of the SPTB gene, thus confirming its aberrant translation. The novel variant was the probable genetic etiology of the proband with HS. Our findings expanded the variant spectrum of the SPTB gene, thus improving the understanding of the associated hereditary hemolytic disorders from a clinical and molecular perspective and contributing to the foundation of genetic counseling and diagnosis.

Clinical and genetic characteristics of Chinese pediatric and adult patients with hereditary spherocytosis.

OBJECTIVE: This study aimed to investigate the clinical features, pathogenic gene variants, and potential genotype-phenotype correlations in Chinese patients with hereditary spherocytosis (HS). METHODS: Retrospective analysis of clinical data and molecular genetic characteristics was conducted on patients diagnosed with HS at Jiangxi Provincial Children's Hospital, the Second Affiliated Hospital of Nanchang University, Pingxiang People's Hospital and The Third People's Hospital of Jingdezhen between November 2017 and June 2023. Statistical analyses were performed to compare and analyze the red blood cell (RBC), hemoglobin (HB), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) data between and within groups based on different mutations and age groups (< 14 and ≥ 14 years). RESULTS: A total of 34 HS patients were included in this study, comprising 22 children (64.70%) and 12 adults (35.30%). The probands who underwent genetic testing were derived from 34 unrelated families. Thirty-two variants were tested and 9 of them are novel. Eighteen cases had ANK1 variants, 15 had SPTB variants, and 1 had SLC4A1 variant. 25 patients performed core family members underwent genetic testing, 17 (68.0%, 17/25) were de novo, 5 (20.0%, 5/25) were maternally inherited, and 3 (12.0%, 3/25) were paternally inherited. ANK1-HS patients exhibited more severe anemia compared to cases with SPTB-HS, showing lower levels of RBC and HB (P < 0.05). Anemia was more severe in patients diagnosed in childhood than in those diagnosed in adulthood. Within the ANK1-HS group, MCH levels in adult patients was significantly higher than those in children (P < 0.05), while there were no significant differences in RBC, HB, MCV, and MCHC levels between two groups. Adult patients with SPTB-HS had significantly higher levels of RBC, HB, and MCH than pediatric patients (P < 0.05), while MCV and MCHC levels showed no significant statistical differences. CONCLUSION: This study conducted a comparative analysis of phenotypic characteristics and molecular genetics in adult and pediatric patients diagnosed with HS, confirming that pediatric ANK1-HS patients exhibit a more severe anemic phenotype compared to SPTB-HS patients, while the severity of HS in adults does not significantly differ between different causative genes.

Hereditary Spherocytosis with Mitochondrial Retention, Increased Oxidative Stress, and Alterations to Bioactive Membrane Lipids.

The clinical course for Hereditary Spherocytosis (HS) patients is highly varied, even within families with identical driving mutations. Here, we describe four siblings with HS attributed to an unreported SPTB mutation. All patients displayed an increased fraction of mitochondria-positive erythrocytes. This was associated with increased reactive oxygen species (ROS) generation and alteration to alterations to bioactive membrane lipids associated with oxidant stress. Given the early promise for mitophagy-inducing agents in sickle cell disease and ready availability of antioxidants, this concept warrants continued exploration as a disease-modifying factor and a potential target for therapy.

Comparative histological analysis of spleens in pediatric patients with hemolytic anemias: Insights into the pathophysiological mechanisms of spleen destruction in sickle cell anemia.

While sickle cell anemia (SCA) and hereditary spherocytosis (HS) share common features of increased spleen erythrophagocytosis due to increased red blood cell (RBC) turnover, SCA is specifically characterized by susceptibility to infections. In this study, histological lesions in the spleens of pediatric patients with SCA were analyzed, in close correlation with past clinical history and comparatively to HS, healthy and transfused ß-thalassemia patients (TDT). An evaluation of red pulp elementary lesions (red pulp fibrosis, iron deposition, number of Gandy-Gamna, and RBC trapping) combined into a severity score was established, as well as B-cell follicles analysis. Quantification on digitalized slides of iron deposition, RBC trapping, and red pulp fibrosis was additionally performed. Spleens from 22 children with SCA, eight with HS, eight with TDT, and three healthy controls (HC) were analyzed. Median age at splenectomy was not different between SCA and HS patients, 6.05 years (range: 4.5-16.0) versus 4.75 (range: 2.2-9.5). Marked heterogeneity was found in SCA spleens in contrast to other conditions. Contrary to previous reports, B-cell follicles were generally preserved in SCA. While RBC trapping was significantly increased in both SCA and HS (compared to TDT and HC), quantitative fibrosis and overall red pulp severity score were significantly increased in SCA spleens compared to other conditions. Moreover, there was an inverse correlation between quantitative fibrosis and number of B-cell follicles, linking these two compartments as well as spleen fibrosis to infectious susceptibility in SCA, potentially through impaired red pulp macrophage scavenging and B-cell subpopulations defects.

Precise diagnosis of a hereditary spherocytosis patient with complicated hematological phenotype.

Hereditary spherocytosis (HS) is one of the most common causes of hereditary hemolytic anemia. The current diagnostic guidelines for HS are mainly based on a combination of physical examination and laboratory investigation. However, some patients present with complicated clinical manifestations that cannot be explained by routine diagnostic protocols. Here, we report a rare HS case of mild anemia with extremely high indirect bilirubin levels and high expression of fetal hemoglobin. Using whole exome sequencing analysis, this patient was identified as a heterozygous carrier of a de novo SPTB nonsense mutation (c.605G > A; p.W202*) and a compound heterozygous carrier of known UGT1A1 and KLF1 mutations. This genetic analysis based on the interpretation of the patient's genomic data not only achieved precise diagnosis by an excellent explanation of the complicated phenotype but also provided valuable suggestions for subsequent appropriate approaches for treatment, surveillance and prophylaxis.

Could the 14q23.2 microdeletion or AKAP5 haploinsufficiency be a potential cause of intellectual disability?

Intellectual disability is characterized by impairment in at least two of the following areas: social skills, communication skills, self-care tasks, and academic skills. These impairments are evaluated in relation to the expected standards based on the individual's age and cultural levels. Additionally, intellectual disability is typically defined by a measurable level of intellectual functioning, represented by an intelligence quotients core of 70 or below. Autism spectrum disorder is a developmental disability resulting from differences in the brain, often characterized by problems in social communication and interaction, and limited or repetitive behaviors or interests. Hereditary spherocytosis is a disease characterized by anemia, jaundice, and splenomegaly as a result of increased tendency to hemolysis with morphological transformation of erythrocytes from biconcave disc-shaped cells with central pallor to spherocytes lacking central pallor due to hereditary injury of cellular membrane proteins. An 11-year-old female patient was referred to Pediatric Genetics Subdivision due to the presence of growth retardation and a diagnosis of hereditary spherocytosis. Since she also had dysmorphic facial features, such as frontal bossing, broad and prominent forehead, tubular nasal structure, and thin vermillion, genetic tests were performed. Chromosomal microarray analysis revealed a 2.5 Mb deletion in the 14q23.2q23.3 region. Deletion was also identified in the same region in her father, who had the same phenotypic characteristics, including hereditary spherocytosis and learning difficulties. We propose that the PLEKHG3 and AKAP5 genes, which are located in this region, may contribute to the development of intellectual disability.

Minimal endoscopic sphincterotomy followed by papillary balloon dilation to relieve choledocholithiasis in a 6-year-old girl with hereditary spherocytosis.

A 6-year-old girl previously diagnosed with hereditary spherocytosis was admitted to our hospital with gallstones and cholangitis. Endoscopic retrograde cholangiopancreatography (ERCP) was performed, and fluoroscopy revealed a dilated common bile duct (CBD) without evident stones, possibly due to spontaneous excretion through the papilla of Vater. A 7-French plastic stent was inserted into the CBD. After the procedure, a marked increase in pancreatic enzyme levels was observed, and she was diagnosed with post-ERCP pancreatitis (PEP). Stent placement could have been a cause of pancreatitis; therefore, we removed the stent. Subsequently, recovery from pancreatitis was confirmed, although she suddenly complained of abdominal pain and was diagnosed with choledocholithiasis recurrence. ERCP was repeated, and fluoroscopy revealed a dilated CBD with a stone. A minimal endoscopic sphincterotomy (EST) was performed to reduce the risk of PEP, and a biliary dilation balloon placed across the papilla was gradually inflated until the waist of the balloon disappeared. Stones were extracted using a retrieval balloon catheter. The abdominal pain resolved immediately, and the patient recovered without developing PEP. To our knowledge, this is the first case report of a pediatric patient treated with minimal EST followed by papillary balloon dilation for choledocholithiasis.

Reticulocyte Antioxidant Enzymes mRNA Levels versus Reticulocyte Maturity Indices in Hereditary Spherocytosis, ß-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 ß-thalassemia (ß-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 ß-thal patients showed younger reticulocytes, with higher transcript levels of all enzymes, although with different patterns. ß-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.

Temporal trends of splenectomy in pediatric hospitalizations with hereditary spherocytosis from 2000 to 2019: A national survey.

BACKGROUND: Total and partial splenectomy are used in pediatric patients with hereditary spherocytosis to resolve anemia and hemolytic complications. PROCEDURE: Data from the Healthcare Cost and Utilization Project's Kid's Inpatient Database was used to profile and describe temporal trends in pediatric (≤18 years) hospital admissions in the United States from 2000 to 2019 data release years. Survey sampling methods were used to produce national estimates. RESULTS: From 2000 to 2019, the use of splenectomy declined overall, from 427 to 206 weighted procedures (difference = 222, 95% confidence interval [CI]: 124-320; p < .0001); the risk of undergoing splenectomy during admission also declined from 56.7% to 38.7% (risk difference = 17.9 percentage points [p.p.], 95% CI: 9.7-26.1; p < .0001). Total splenectomy was mostly used. Age at time of splenectomy increased 10.2 years (difference = 1.6 years, 95% CI: 0.6-2.7; p = .0018). The risk of splenectomy increased with age until 10 years, then leveled off until 18 years. The proportion of children aged ≤5 years undergoing splenectomy decreased from 27.7% to 11.2% in 2019 (risk difference: 16.5 p.p., 95% CI: 7.3-25.7; p = .0004). The strongest clinical predictors of splenectomy, adjusting for patient- and hospital-level characteristics, were a co-diagnosis of symptomatic cholelithiasis (adjusted odds ratio [aOR] = 3.18, 95% CI: 1.92-5.28; p < .0001) and splenomegaly or hypersplenism (aOR = 2.52, 95% CI: 1.74-3.65; p < .0001). Risk of splenectomy with splenomegaly or hypersplenism increased over time. CONCLUSION: Splenectomy was delayed until age greater than 10 years. Older age, co-diagnosis with splenomegaly or hypersplenism, or symptomatic cholelithiasis were strongest clinical predictors of splenectomy. Conservative management of hereditary spherocytosis appears to be more common.

Coinheritance of hereditary spherocytosis with haemochromatosis: next-generation sequencing reveals.

We report the case of a man in his 50s with extravascular haemolysis, fluctuating indirect hyperbilirubinaemia, elevated transferrin saturation with hyperferritinaemia and normal liver enzymes. Spherocytes were detected in a blood smear and a mutation of unknown significance, c.1626+1G>A p.?, in intron 13 of the SLC4A1 gene, was identified by next-generation sequencing (NGS). The same mutation was found in his daughter, who presented with similar laboratory changes, confirming the diagnosis of hereditary spherocytosis. Abdominal MRI showed hepatosplenomegaly with hepatic iron overload. In this context of haemolysis (without anaemia) and iron overload, a diagnosis of haemochromatosis was presumed. NGS confirmed the presence of the variants p.(His63Asp) and p.(Cys282Tyr) in heterozygosity in the HFE gene. We report this case for the rarity of co-existing two haematological diseases counteracting each other.

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.

Molecular characteristics of hereditary red blood cell membrane disorders in Thailand: a multi-center registry.

Red blood cell (RBC) membrane disorders represent a significant category of hereditary hemolytic anemia; however, information from Southeast Asia is limited. We established a national registry aiming to characterize RBC membrane disorders and their molecular features in Thailand. A total of 100 patients (99 kindreds) diagnosed with RBC membrane disorders between 2011 and 2020 from seven university hospitals were enrolled. The most prevalent disorders observed were hereditary elliptocytosis (HE; n=33), hereditary pyropoikilocytosis (HPP; n=28), hereditary spherocytosis (HS; n=19), Southeast Asian ovalocytosis (SAO; n=10 of 9 kindreds), and two cases of homozygous SAO. The remaining cases were grouped as unclassified membrane disorder. Seventy-six patients (76%) were molecularly confirmed by PCR, direct DNA sequencing, or hi-throughput sequencing. The primary causative gene for HE and HPP was SPTB, accounting for 28 out of 29 studied alleles for HE and 56 of 56 studied alleles for HPP. In the case of HS, dominant sporadic mutations in the ANK1 gene (n=4) and SPTB gene (n=3) were identified as the underlying cause. Notably, the four most common variants causing HE and HPP were SPTB Providence (c.6055 T>C), SPTB Buffalo (c.6074 T>G), SPTB Chiang Mai (c.6224 A>G), and SPTB c.6171__82delins TGCCCAGCT. These recurrent SPTB mutations accounted for 79 out of 84 mutated SPTB alleles (94%). In summary, HE and hereditary HPP associated with recurrent SPTB mutations are the predominant types of RBC membrane disorders observed in Thailand. These findings have significant implications for the clinical management and future research of RBC membrane disorders in the region.

Hereditary Spherocytosis: Can Next-Generation Sequencing of the Five Most Frequently Affected Genes Replace Time-Consuming Functional Investigations?

Congenital defects of the erythrocyte membrane are common in northern Europe and all over the world. The resulting diseases, for example, hereditary spherocytosis (HS), are often underdiagnosed, partly due to their sometimes mild and asymptomatic courses. In addition to a broad clinical spectrum, this is also due to the occasionally complex diagnostics that are not available to every patient. To test whether next-generation sequencing (NGS) could replace time-consuming spherocytosis-specific functional tests, 22 consecutive patients with suspected red cell membranopathy underwent functional blood tests. We were able to identify the causative genetic defect in all patients with suspected HS who underwent genetic testing (n = 17). The sensitivity of the NGS approach, which tests five genes (ANK1 (gene product: ankyrin1), EPB42 (erythrocyte membrane protein band4.2), SLC4A1 (band3), SPTA1 (α-spectrin), and SPTB (ß-spectrin)), was 100% (95% confidence interval: 81.5-100.0%). The major advantage of genetic testing in the paediatric setting is the small amount of blood required (<200 µL), and compared to functional assays, sample stability is not an issue. The combination of medical history, basic laboratory parameters, and an NGS panel with five genes is sufficient for diagnosis in most cases. Only in rare cases, a more comprehensive functional screening is required.

[Clinical and genotypic analysis of hereditary spherocytosis combined with cholestasis among pediatric patients].

Objective: To understand the clinical and genetic characteristics of hereditary spherocytosis (HS) combined with cholestasis among pediatric patients. Methods: 12 cases of HS children accompanied by cholestasis at Hunan Children's Hospital were selected as the research subjects between January 2013 and December 2022. Clinical data were collected. Whole-exome sequencing was performed by second-generation sequencing. Suspected pathogenic mutation sites were verified by Sanger sequencing. Results: All pediatric patients were admitted to the hospital due to their yellow skin tone. Eight cases (66.67%) had a positive family history. The clinical manifestations were jaundice, splenomegaly (12/12), abdominal pain, anemia (4/12), and hepatomegaly (5/12). All pediatric patients had decreased hemoglobin, an increased reticulocyte ratio, total bilirubin and direct bilirubin, a positive erythrocyte fragility test, and remarkable spherical erythrocytes in their peripheral blood. Seven cases had elevated aminotransferase; four cases had severely elevated aminotransferase and bilirubin; eight cases had biliary calculi; and two cases had a dilated biliary tract. Liver pathological examination showed mild damage to the liver cells (G1S1) in three pediatric cases. Five children had a total of six unreported mutations: SPTB gene c.2431_2450del, c.4974-2A > G, c.2575G > A, and exon 22-35 deletion; ANK1 gene: c.2379-2380delC; and c .6dupC. Children still had abnormal bilirubin levels following treatment. Two pediatric cases underwent splenectomy. Bilirubin and hemoglobin levels returned to normal after surgery. Conclusion: Children with HS may experience cholestasis, and those with poor treatment results may consider undergoing a splenectomy. Six new types of variants have expanded the HS gene mutation spectrum.

Long-term haematological response and maintained immunological function after laparoscopic subtotal splenectomy in patients with hereditary spherocytosis.

INTRODUCTION: Subtotal or total splenectomy are recommended in severe and should be considered in intermediate forms of hereditary spherocytosis (HS). Data on laparoscopic subtotal splenectomy (LSTS) in HS patients are sparse. METHODS: Thirty three patients with HS (median age 10.7 years (yrs), range 1.8-15.5) underwent LSTS. Baseline and follow-up investigation included haematological parameters, microscopic analysis of pitted erythrocytes (pitE), and B-cell subpopulations assessed by flow cytometry. Results were compared to those of non-splenectomised HS patients, HS patients after total splenectomy (TS), and healthy individuals. RESULTS: After LSTS, haemoglobin levels were normalised in all patients. During median long-term follow-up of 3.9 yrs (range 1.1-14.9), only four patients presented mild anaemia. Despite re-growing of the remnant spleen none of the patients required a second surgical intervention. As compared to TS, PitE in LSTS patients were significantly lower and indicated normal to only moderately decreased spleen function. Relative but not absolute IgM memory B-cell counts were reduced in both LSTS and TS patients. CONCLUSIONS: LSTS is effective for the treatment of patients with HS. A small remnant spleen is sufficient to provide adequate phagocytic function and to induce a pool of IgM memory B-cells.

Mitapivat reprograms the RBC metabolome and improves anemia in a mouse model of hereditary spherocytosis.

Hereditary spherocytosis (HS) is the most common, nonimmune, hereditary, chronic hemolytic anemia after hemoglobinopathies. The genetic defects in membrane function causing HS lead to perturbation of the RBC metabolome, with altered glycolysis. In mice genetically lacking protein 4.2 (4.2-/-; Epb42), a murine model of HS, we showed increased expression of pyruvate kinase (PK) isoforms in whole and fractioned RBCs in conjunction with abnormalities in the glycolytic pathway and in the glutathione (GSH) system. Mitapivat, a PK activator, metabolically reprogrammed 4.2-/- mouse RBCs with amelioration of glycolysis and the GSH cycle. This resulted in improved osmotic fragility, reduced phosphatidylserine positivity, amelioration of RBC cation content, reduction of Na/K/Cl cotransport and Na/H-exchange overactivation, and decrease in erythroid vesicles release in vitro. Mitapivat treatment significantly decreased erythrophagocytosis and beneficially affected iron homeostasis. In mild-to-moderate HS, the beneficial effect of splenectomy is still controversial. Here, we showed that splenectomy improves anemia in 4.2-/- mice and that mitapivat is noninferior to splenectomy. An additional benefit of mitapivat treatment was lower expression of markers of inflammatory vasculopathy in 4.2-/- mice with or without splenectomy, indicating a multisystemic action of mitapivat. These findings support the notion that mitapivat treatment should be considered for symptomatic HS.

Next generation sequencing (NGS) interest in deciphering erythrocyte molecular defects' association in red cell disorders: Clinical and erythrocyte phenotypes of patients with mutations inheritance in PIEZO1, Spectrin ß1, RhAG and SLC4A1.

We report here an instructive case referred at 16 months-old for exploration of hemolysis without anemia (compensated anemia with reticulocytosis). The biology tests confirmed the hemolysis with increased total and indirect bilirubin. The usual hemolysis diagnosis tests were normal (DAT, G6PD, PK, Hb electrophoresis) except cytology and ektacytometry suggesting an association of multiple red blood cell (RBC) membrane disorders. This led us to propose a molecular screening analysis using targeted-Next Generation Sequencing (t-NGS) with a capture technique on 93 genes involved in RBC and erythropoiesis defects. We identified 4 missense heterozygous allelic variations, all of them were described without any significance (VUS) in the SLC4A1, RhAG, PIEZO1 and SPTB genes. The study of the familial cosegregation and research functional tests allowed to decipher the role of at least two by two genes in the phenotype and the hemolytic disease of this young patient. Specialized t-NGS panel (or virtual exome/genome sequencing) in a disease-referent laboratory and the motivated collaboration of clinicians, biologists and scientists should be the gold standard for improving the diagnosis of the patients affected with RBC diseases or rare inherited anemias.