TSEN2 constitutes one of the two catalytic subunits of the tRNA splicing endonuclease (TSEN) complex, which is responsible for removing introns from precursor tRNAs (pre-tRNAs) 12. The human TSEN complex comprises four subunits (TSEN2, TSEN15, TSEN34, and TSEN54) that collectively recognize and cleave pre-tRNA at both 5' and 3' splice sites 1. TSEN2 specifically carries the active site for 5'-splice site cleavage, working in coordination with TSEN54 for 3'-splice site cleavage 2. Structural studies reveal that TSEN2, along with TSEN34 and TSEN54, recognizes the mature domain of pre-tRNA through conserved structural elements, positioning the anticodon stem to place splice sites into their respective catalytic centers 1. The complex employs a molecular ruler mechanism where the mature tRNA body is recognized while intron sequences make no direct contact with TSEN, allowing accommodation of varying intron lengths 1. Disease relevance is significant, as biallelic pathogenic variants in TSEN2 cause pontocerebellar hypoplasia type 2B (PCH2B), characterized by cerebellar hypoplasia, progressive microcephaly, developmental delay, and seizures 34. Additionally, specific TSEN2 mutations have been associated with atypical hemolytic uremic syndrome, suggesting a connection between tRNA biology and vascular endothelium homeostasis 5.