A Novel Synonymous Mutation in ANK1 that Causes Hereditary Spherocytosis by Affecting Splicing

Hereditary spherocytosis (HS), a genetic disorder characterized by hemolytic anemia, is primarily caused by mutations in erythrocyte membrane protein genes, with ANK1 mutations being prevalent in Chinese populations. While synonymous mutations were traditionally considered non-pathogenic, emerging evidence suggests their potential to disrupt mRNA splicing and protein function. This case report describes a 3-year-old Chinese boy presenting with typical HS symptoms, including anemia, splenomegaly, and spherocytosis. Genetic analysis via next-generation sequencing (NGS) identified a novel heterozygous synonymous mutation in ANK1 (c.1305G>C, p.V435V), inherited from his father, who had a history of HS and improved post-splenectomy. Splicing prediction tools (SpliceAI) and RNA-level validation revealed that this mutation induced a 229-nucleotide insertion from intron 12, leading to premature termination of ankyrin protein translation. Evolutionary conservation analysis highlighted the critical role of the mutated site in maintaining protein structure.