Evaluation of a Flow-Cytometric Osmotic Fragility Test for Hereditary Spherocytosis in Chinese Patients

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.

Identification of a novel ANK1 gene variant c.1504-9G>A and its mechanism of intron retention in hereditary spherocytosis

Objective: The objective of this study was to pinpoint pathogenic genes and assess the mutagenic pathogenicity in two pediatric patients with hereditary spherocytosis. Methods: We utilized whole-exome sequencing (WES) for individual analysis (case 1) and family-based trio analysis (case 2). The significance of the intronic mutation was validated through a Minigene splicing assay and supported by subsequent in vitro experiments. Results: Both probands received a diagnosis of hereditary spherocytosis. WES identified a novel ANK1 c.1504-9G>A mutation in both patients, causing the retention of seven nucleotides at the 5' end of intron 13, as substantiated by the Minigene assay. This variant results in a premature stop codon and the production of a truncated protein. In vitro studies indicated a reduced expression of the ANK1 gene. Conclusion: The novel ANK1 c.1504-9G>A variant is established as the causative factor for hereditary spherocytosis, with the c.1504-9G site functioning as a splicing receptor.

Clinical Characteristics and Treatment Outcome of Hereditary Spherocytosis: A Single Center's Experience

Objectives

The objective of the study is to present the demographic characteristics, clinical and laboratory features and outcome of our patients with hereditary spherocytosis (HS).

Methods

Demographic, clinical, and laboratory data; complications; and splenectomy results were analyzed retrospectively. The severity of the disease was scaled according to Eber's criteria.

Results

Sixty-nine patients (42 boys, 27 girls, median age: 3 years) were eligible. Sixty-eight percent of the patients had a history of neonatal jaundice. The complaints at admission were jaundice (71%), fatigue (27.5%), fainting (4.3%), and pallor (4.3%). The median follow-up duration was 8.5 years. According to Eber's criteria, three (4.3%), 57 (82.6%), and nine (13.1%) patients had mild, moderate, and severe diseases, respectively. Thirty-six patients (52.1%) had a splenectomy. Following splenectomy, we observed a significant rise in hemoglobin levels and a decline in indirect bilirubin levels. Post-operative thrombocytosis was common, with a tendency to fall and stabilize after 1 month. There were no thromboembolic complications.

Conclusion

In spite of the high rate of consanguinity, familial history of HS, and neonatal jaundice in our study group, the majority of the HS patients were identified relatively late, about 3 years. This finding shows that HS might be insufficiently acknowledged by primary care. Splenectomy, in selected cases, may reduce the need for transfusions. Post-splenectomy transient thrombocytosis is common and has a benign course.

Intraoperative Cell-Saver Caused More Autologous Salvage Hemolysis in a Hereditary Spherocytosis Patient Than in a Normal Erythrocyte Patient

Hereditary spherocytosis is a common red blood cell disease caused by an inherited red blood cell membrane defect, leading to a spherical shape and propensity for hemolysis. There is a lack of reports on intraoperative autologous blood transfusion for hereditary spherocytosis patients. We hereby report our recent experience with using the Cell Saver^® system for intraoperative red blood cell salvage on a hereditary spherocytosis patient. There was a drastic increase in salvaged blood free-hemoglobin compared with the preoperative sample (82.6 mg/dl vs. 6.2 mg/dl) which indicated severe hemolysis. Although our patient recovered smoothly with a normal liver and renal function test and reported no adverse reaction during follow-up, it is noteworthy that severe hemolysis could happen during the cell salvage process for patients with hemolytic anemia, as there are similar reports on sickle cell anemia, beta-thalassemia intermedia, and paroxysmal nocturnal hemoglobinuria. Therefore, more clinical attention and thorough research should be drawn into this perspective, namely, hemolysis during the red blood cell salvage process for patients with hemolytic anemia.

Study on Management of Blood Transfusion Therapy in Patients with Hereditary Spherocytosis

Hereditary spherocytosis (HS) is a chronic hemolytic disorder caused by inherited defects in the red blood cell membrane. This study discusses the treatment strategy for the decline in hemoglobin level in three HS probands with moderately severe or severe hemolysis and summarizes the appropriate laboratory tests that help improve clinical management of blood transfusion in HS patients. Three probands who were diagnosed with HS in our hospital and their family members were included in this study. Clinical data of the three families were reviewed to summarize their hematopoietic characteristics. DNA from all family members of the 3 HS probands was amplified by polymerase chain reaction (PCR) and sequenced by the Sanger method to assess genetic relation for HS. Based on the sequencing results, the type of mutated membrane protein in each proband was analyzed using the eosin-5'-maleimide (EMA) binding test and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The hemoglobin level was reduced in all 3 probands after different levels of infection. The fluorescence of EMA-labeled red blood cell (RBC) was decreased. DNA sequencing showed that His54Pro, Leu1858Val, and 6531-12C>T compound heterozygous mutations were present in the SPTA1 gene of patient I-1, Arg344Gln and c.609+86G>A heterozygous mutations were present in the SLC4A1 gene of patient II-1, and Leu2032Pro homozygous mutation was present in the SPTB gene of patient III-1. SDS-PAGE results demonstrated that the concentration of band 3 was reduced in II-1, whereas the levels of the corresponding mutant proteins in the other probands were unchanged. The family members of the respective patients presented mutations in major genes causing HS. The Leu2032Pro mutation identified in patient III-1 is a new missense mutation of the SPTB gene in the Chinese population that has never been reported in literature previously. The presence or absence of acute or chronic infections is a critical deciding factor for the treatment and clinical management of HS patient via blood transfusion. For patients with infections, hemoglobin concentration can be restored once the infection is controlled, thus obviating the need for proper infection control before blood transfusion.

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.

Two novel ANK1 loss-of-function mutations in Chinese families with hereditary spherocytosis

Hereditary spherocytosis (HS) is the most common inherited haemolytic anaemia disorder. ANK1 mutations account for most HS cases, but pathogenicity analysis and functional research have not been widely performed for these mutations. In this study, in order to confirm diagnosis, gene mutation was screened in two unrelated Chinese families with HS by a next‐generation sequencing (NGS) panel and then confirmed by Sanger sequencing. Two novel heterozygous mutations (c.C841T, p.R281X and c.T290G, p.L97R) of the ANK1 gene were identified in the two families respectively. Then, the pathogenicity of the two new mutations and two previously reported ANK1 mutations (c.C648G, p.Y216X and c.G424T, p.E142X) were studied by in vitro experiments. The four mutations increased the osmotic fragility of cells, reduced the stabilities of ANK1 proteins and prevented the protein from localizing to the plasma membrane and interacting with SPTB and SLC4A1. We classified these four mutations into disease‐causing mutations for HS. Thus, conducting the same mutation test and providing genetic counselling for the two families were meaningful and significant. Moreover, the identification of two novel mutations enriches the ANK1 mutation database, especially in China.

Old and new insights into the diagnosis of hereditary spherocytosis

Hereditary spherocytosis (HS) belongs to the group of congenital hemolytic anemias resulting from plasma membrane protein deficiency. When diagnosed too late, HS bares the risk of long-term complications including gall stones and severe anemia. Here, there are discussed advances in HS screening and diagnostics, with a particular focus on methodologies, most of which are available in clinical laboratories worldwide.

Molecular Genetic Mechanisms of Hereditary Spherocytosis: Current Perspectives

With the widespread use of genetic diagnostic technologies, many novel mutations have been identified in hereditary spherocytosis (HS)-related genes, including SPTA1, SPTB, ANK1, SLC4A1, and EPB42. However, mutations in HS-related genes are dispersed and nonspecific in the diagnosis of some HS patients, indicating significant heterogeneity in the molecular deficiency of HS. It is necessary to provide the molecular and genetic characteristics of these 5 genes for clinicians to examine HS. Here, we reviewed the recent proposed molecular genetic mechanisms of HS.

Flow cytometric analysis of patients with hereditary spherocytosis - an Indian scenario

OBJECTIVES

Flow cytometry osmotic fragility test (FC-OFT) was a recently introduced screening test for hereditary spherocytosis (HS). This study was conducted to evaluate the utility of FC-OFT in all newly diagnosed cases of HS, to compare its diagnostic value with conventional OFT and to correlate with clinical disease severity.

METHODS

In this study, the percentage of residual red cells (%RRC) was measured using flow cytometer after creating a red cell suspension. Subsequently, this was spiked with deionized water for FC-OFT in all cases of HS (n = 40), healthy subjects (n = 40) and beta-thalassemia traits (BTT) (n = 20).

RESULTS

The receiver operator curve analysis defined the optimal cut-offs for FC-OFT-derived indices, such as %RRC value (≤16.29%) and %RRC ratio (>1.72), for HS cases when compared with healthy subjects and BTT (p < 0.05). The FC-OFT (96%) achieved higher test efficiency than the conventional OF test (68.9%). A significant positive and a negative correlation were found between number of spherocytes/hpf and %RRC ratio (p = 0.001) and %RRC values (p = 0.0486). No significant correlation was observed between %RRC value (p = 0.8934), %RRC ratio (p = 0.6348) and HS disease severity score.

CONCLUSION

Our results suggest that FC-OFT could be the better screening test for HS cases in developing countries if flow cytometer is available.