TSEN34 (tRNA splicing endonuclease subunit 34) is one of two catalytic subunits of the tRNA splicing endonuclease (TSEN) complex, which is essential for pre-tRNA maturation in eukaryotes 1. TSEN34 specifically catalyzes 3'-splice site cleavage, cleaving precursor-tRNA at invariant positions to release the intron and generate tRNA half-molecules with 2',3'-cyclic phosphate and 5'-OH termini 2. The TSEN complex recognizes the mature tRNA body through conserved structural elements in TSEN34, TSEN54, and TSEN2, positioning the anticodon stem correctly for catalysis via a molecular ruler mechanism 1. Notably, TSEN34 also functions in mRNA 3'-end processing, linking pre-tRNA splicing to pre-mRNA maturation 3. Clinically, recessive TSEN34 mutations cause pontocerebellar hypoplasia (PCH), a neurodegenerative disorder characterized by cerebellar and pontine hypoplasia, microcephaly, developmental delay, and dyskinesia 45. Mutations in TSEN34 occur less frequently than TSEN54 mutations in PCH2 but produce similar phenotypes including progressive microcephaly and variable motor impairment 6. The functional importance of TSEN34 in tRNA biogenesis appears critical for proper brain development, as defective TSEN34 leads to altered tRNA transcripts and severe neurological dysfunction 7.