The specificity of 93.33% suggested that serum SV2A was an excellent biomarker of discriminating AD from PDD (Table 2), to improve its sensitivity, we combined serum SV2A with NfL, GFAP, or p-tau217 by the parallel test and found that the sensitivity of 64.63% increased to 83.5%, 93.3%, and 88.4%, respectively, while the sensitivity of the diagnostic model combining the four markers increased to 97.6% (Table 3). The gene discussed is GFAP; the disease is Alzheimer disease.