A novel mutation in SPTA1 identified by whole exome sequencing in a Chinese family for hereditary elliptocytosis presenting with hyperbilirubinemia: A case report

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

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

A Novel SPTA1 Mutation in a Patient with Hereditary Spherocytosis without a Family History and Coexisting Gilbert's Syndrome

Most patients with hereditary spherocytosis (HS) have a family history of disease, while those without such a history are difficult to diagnose. We herein report a case of HS with no family history harboring a novel heterozygous mutation of SPTA1, c.2161G>A (p.E721K), and a homozygous polymorphism of UGT1A1*6. In silico analyses suggested that the mutation might contribute to the pathogenesis of HS. The coexistence of HS and Gilbert's syndrome increases the risk of gallstones. Therefore, splenectomy, alone or in combination with cholecystectomy, is recommended. The determination of genetic diathesis provides useful information for the management of hemolytic anemia.

A novel EPB41 p.Trp704* mutation in a Korean patient with hereditary elliptocytosis: a case report

Objectives: Hereditary elliptocytosis (HE) is inherited in an autosomal dominant fashion, and the majority of HE-associated defects occur due to qualitative and quantitative defects in the RBC membrane skeleton proteins α-spectrin, β-spectrin, or protein 4.1R. The complex EPB41 gene encodes a diverse family of protein 4.1R isoforms which are key components of the erythroid membrane skeleton that regulates red cell morphology and mechanical stability. The purpose of this study was to investigate the genome of a Korean patient with HE to discover the causative gene mutation using gene panel sequencing. Methods: An 89-year-old female presented to the Emergency Department and was diagnosed with pancreatitis and gallstones. A peripheral blood smear revealed that approximately 60% of the RBCs were abnormally shaped and appeared oval or elongated, from slightly egg-shaped to rod or pencil forms (elliptocytes). Targeted gene panel sequencing consisting of 33 genes related to inherited RBC disorders and Sanger sequencing were performed. Results: A heterozygous c.2112G > A of the EPB41 gene leading to premature termination codon (NM_001166005.1:c.2112G > A, p.Trp704*) was identified. This variant, which had not been previously reported to be related to HE, was confirmed by Sanger sequencing. Thus, the patient's diagnosis of HE-1 was genetically confirmed. Conclusion: The present study confirmed a novel mutation of the EPB41 gene that plays an important role in expanding the mutational distribution in HE-1. It could also be helpful for understanding the correlation between the genotype and phenotype in HE.

Human erythrocytes: cytoskeleton and its origin

In the last few years, erythrocytes have emerged as the main determinant of blood rheology. In mammals, these cells are devoid of nuclei and are, therefore, unable to divide. Consequently, all circulating erythrocytes come from erythropoiesis, a process in the bone marrow in which several modifications are induced in the expression of membrane and cytoskeletal proteins, and different vertical and horizontal interactions are established between them. Cytoskeleton components play an important role in this process, which explains why they and the interaction between them have been the focus of much recent research. Moreover, in mature erythrocytes, the cytoskeleton integrity is also essential, because the cytoskeleton confers remarkable deformability and stability on the erythrocytes, thus enabling them to undergo deformation in microcirculation. Defects in the cytoskeleton produce changes in erythrocyte deformability and stability, affecting cell viability and rheological properties. Such abnormalities are seen in different pathologies of special interest, such as different types of anemia, hypertension, and diabetes, among others. This review highlights the main findings in mammalian erythrocytes and their progenitors regarding the presence, conformation and function of the three main components of the cytoskeleton: actin, intermediate filaments, and tubulin.