AUTHOR=Xi Bixin , Liu Siying , Zhu Yongbing , Zhang Dedong , Zhang Yu , Liu Aiguo 

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

JOURNAL=Frontiers in Genetics

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2023.1309040

DOI=10.3389/fgene.2023.1309040

ISSN=1664-8021

ABSTRACT=<p><bold>Background:</bold> 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 (<italic>SPTB</italic>), variants are located in exons and give rise to mRNA defects. However, the genetic characteristics and pathogenic mechanisms of <italic>SPTB</italic> intronic variants are not completely understood. This study aimed to analyse a rare intronic inversion variant in the <italic>SPTB</italic> gene associated with HS, and explore the impact of the variant on <italic>SPTB</italic> mRNA splicing.</p><p><bold>Method:</bold> 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 <italic>SPTB</italic> gene splicing and expression were affected.</p><p><bold>Results:</bold> Targeted next-generation sequencing identified a novel disease-associated intronic inversion variant of the <italic>SPTB</italic> 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 <italic>SPTB</italic> mRNA.</p><p><bold>Conclusion:</bold> This study identifies a rare intronic inversion variant in the <italic>SPTB</italic> gene associated with hereditary spherocytosis. The pathogenic variant can lead to exon 20 skipping and decreased <italic>SPTB</italic> gene expression. This finding has not been previously reported in any literature. This study can expand the intronic variant spectrum of the <italic>SPTB</italic> gene, deepen our understanding of HS pathogenesis, and contribute to the genetic diagnosis and clinical management of patients.</p>