Objective: To analyze the clinical characteristics and spectrum of SPTB gene variants among 16 Chinese children with Hereditary spherocytosis (HS) and explore their genotype-phenotype correlation.
Methods: Sixteen children who were diagnosed with HS at the Affiliated Hospital of Capital Institute of Pediatrics from November 2018 to July 2022 were selected as the research subjects. Genetic testing was carried out by whole exome sequencing. Candidate variants were verified by Sanger sequencing and subjected to bioinformatic analysis and prediction of 3D structure of the protein. Correlation between the SPTB genotypes and clinical phenotypes was analyzed using Chi-squared test.
Results: The male-to-female ratio of the HS patients was 6 : 10, with the median age being 7-year-and-10-month. Clinical features of the patients have included anemia, reticulocytosis and gradual onset of splenomegaly. Mild, moderate and severe anemia have respectively occurred in 56.25% (9/16), 31.25% (5/16) and 12.50% (2/16) of the patients. SPTB gene variants were detected in all patients, among which 10 were unreported previously and 7 were de novo in origin. Loss of function (LOF) variants accounted for 93.75% (15/16). Only one missense variant was detected. Eleven, 4 and 1 of the variants had occurred in the repeat domain, CH1 domain, and dimerization domain, respectively. There was no significant correlation between the type or domain of the SPTB gene variants with the clinical features such as severity of anemia (x² = 3.345, P > 0.05). All of the variants were predicted to be pathogenic or likely pathogenic based on the guidelines from the American College of Medical Genetics and Genomics.
Conclusion: Mild to moderate anemia are predominant clinical features of the HS children harboring a SPTB gene variant, for which LOF variants are the main mutational type. The clinical feature of HS is unaffected by the type of the variants.