STX1A and Alzheimer disease: We next performed correlational analyses between PTPRS protein levels and other synaptic markers in the CSF, namely NLGN3, STX1a, DLG4, SYT1, ADAM23, Syntaxin-6, NRG3 and Contactin-5, within the PREVENT-AD cohort using the Somalogic multiplex assay (Fig. 2B).