Identification of new mutations in patients with hereditary spherocytosis by next-generation sequencing

Hereditary spherocytosis (HS) is the most common inherited hemolytic anemia characterized by the presence of spherical-shaped erythrocytes on the peripheral blood smear, hemolysis, splenomegaly, jaundice, and gallstones. To date, mutations in at least five genes (ANK1, EPB42, SLC4A1, SPTA1, and SPTB) have been found to be associated with different subtypes of HS. Here, we aim to investigate the presence of novel as well as known mutations in 35 Chinese patients with clinically suspected HS. Whole-exome sequencing (WES) has identified 3 patients with SLC4A1, 16 patients with ANK1, and 16 patients with SPTB mutations, including 5 splicing, 12 nonsense, 9 frameshift, 7 missense, and 1 start-loss mutation, indicating that SPTB and ANK1 are the most frequently mutated genes in Chinese HS patients. Among 34 mutations identified, 21 were novel. Most of SPTB and ANK1 mutations were nonsense (8/16) and frameshift (6/16) mutations. By trio analysis of eight families we have confirmed six de novo mutations. In addition, genotype–phenotype analysis was also performed by comparing clinical manifestations among three groups of patients with SPTB, ANK1, and SLC4A1 mutations. It revealed that patients with ANK1 mutations had a significantly higher level of MCV and MCH but lower percentage of spherocytes compared with those carrying SPTB mutations. In conclusion, our results suggested that molecular diagnosis by next-generation sequencing (NGS) is a fast, economic, and accurate way to detect and identify pathogenic alterations of inherited diseases, highlighting the potential usage of NGS in clinical practice.