SV2A and Alzheimer disease: Then, we counted the number of SV2A-, GFAP-, NfL-, and p-tau217-positive cases in the AD high-risk group (APOE ε4 carriers) and found that a total of 45 cases were positive for SV2A, with a positivity rate of 81.82%, which was higher than those of GFAP (32.73%) and p-tau217 (36.36%) (Table 7).