PCSK9 and Parkinson disease: Bioinformatics analyses highlighted focal adhesion and JAK-STAT signaling as key pathways, with ICAM1 and ITGB2 as central nodes in the protein-protein interaction network.<h4>Conclusion</h4>All six serum biomarkers showed potential in distinguishing PD-NC from PD-CI, with PCSK9 and LCAT being the most effective.