PPFIA2 and posterior cortical atrophy: Among 20 significantly upregulated circRNAs (Supplementary Fig. S1A), hsa_circ_0099343 (annotated as circPPFIA2) emerged as the lead candidate based on two criteria: (1) its host gene PPFIA2 exhibited the highest baseline expression in PCa cells, suggesting robust transcriptional activity conducive to circRNA biogenesis (Supplementary Fig. S1B); (2) conserved HNRNPL binding motifs were identified within flanking introns of PPFIA2, suggesting direct splicing regulation.