Novel compound heterozygous SPTA1 mutations in a patient with hereditary elliptocytosis

Case report: Whole-exome sequencing for a hereditary elliptocytosis case with an unexpectedly low HbA1c

Objectives

Hereditary elliptocytosis is a group of erythroid hereditary diseases characterized by elliptically shaped erythrocytes in peripheral blood. It is mainly inherited through autosomal dominant inheritance. This study aimed to conduct a genetic etiology analysis in a case with a clinical diagnosis of hereditary elliptocytosis and an unexpectedly low HbA1c.

Methods

Whole-exome sequencing was performed to find the possible pathogenic mutations. At the same time, bioinformatics software was used to predict the mutation function. Sanger sequencing was performed to verify the suspected pathogenic mutations.

Results

Whole-exome sequencing results showed that the proband with mild anemia had a heterozygous c.2303G>A (p.G768D) missense mutation in the 13th exon of the SPTB gene. The Sanger sequencing confirmed this heterozygous mutation. This mutation was extremely rare in the population, and multiple software's predictions were harmful. Conservative analysis revealed that this site was highly conserved in various species.

Conclusion

The c.2303G>A mutation of the SPTB gene is the suspected cause of hereditary elliptocytosis in the patient. Our data show that microscopic examination of red blood cells on blood smears is an important means of diagnosing hereditary elliptocytosis. Whole-exome sequencing is an effective tool to determine the genetic etiology of erythrocyte membrane diseases, which can promote accurate diagnosis and genetic counseling.

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 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.

Clinical features and genetic variations of severe neonatal hyperbilirubinemia: Five case reports

BACKGROUND

Neonatal hyperbilirubinemia is a common problem faced by pediatricians. The role of genetic factors in neonatal jaundice has been gradually recognized. This study aims to identify genetic variants that influence the bilirubin level in five patients using next-generation sequencing (NGS).

CASE SUMMARY

Five neonates with severe hyperbilirubinemia were retrospectively studied. They exhibited bilirubin encephalopathy, hypothyroidism, ABO blood type incompatibility hemolysis, glucose-6-phosphate dehydrogenase (G6PD) deficiency and premature birth, respectively. A customized 22-gene panel was designed, and NGS was carried out for these neonates. Eight variations (G6PD c.G1388A, HBA2 c.C369G, ABCC2 c.C3825G, UGT1A1 c.G211A, SPTB c.A1729G, EPB41 c.G520A, c.1213-4T>G and c.A1474G) were identified in these five neonates. Genetic mutations of these genes are associated with G6PD deficiency, thalassemia, Dubin-Johnson syndrome, Gilbert syndrome, hereditary spherocytosis, and hereditary elliptocytosis. One of the neonates was found to have compound variants of the EPB41 splice site c.1213-4T>G and c.G520A (p.E174K), but no elliptocyte was seen on his blood smear of 4 years old.

CONCLUSION

Pathological factors of severe neonatal hyperbilirubinemia are complicated. Genetic variants may play an important role in an increased risk of neonatal hyperbilirubinemia, and severe jaundice in neonates may be related to a cumulative effect of genetic variants.

Clinical and molecular genetic analysis of a Chinese family with hereditary elliptocytosis caused by a novel mutation in the EPB41 gene

BACKGROUND

Hereditary elliptocytosis (HE) is a heterogeneous red blood cell membrane disorder characterized by the presence of elliptocytes on a peripheral blood smear. Clinical manifestations of HE vary widely from asymptomatic carriers to patients with severe transfusion-dependent anemia. Most patients are asymptomatic or have mild anemia, which hinders diagnosis. The proband in this case had mild anemia and jaundice over a period of 4 years, the etiology of which was unclear. Hence, he was admitted to our hospital for further diagnosis.

METHODS

Peripheral blood smears and routine blood tests were performed and biochemical parameters of the proband, and his family members were determined. To confirm the diagnosis, gene mutations were screened in the proband using next-generation sequencing (NGS) and verified by Sanger sequencing in other family members.

RESULTS

A novel mutation (c.1294delA, p.Ser432 fs) in exon 15 of the EPB41 gene was detected in the proband and his family members. This mutation results in a frameshift and a premature stop codon at position 455, encoding a truncated protein. The variant was likely pathogenic according to the criteria of the American College of Medical Genetics and Genomics. SWISS-MODEL protein structure prediction indicated partial loss of the spectrin and actin binding and C-terminal domains.

CONCLUSION

A heterozygous mutation 1294delA in exon 15 of the EPB41 gene was identified using NGS and Sanger sequencing in members of a Chinese family. This identification expands the spectrum of EPB41 mutations and contributes to the genetic diagnosis of families with HE.