GAP43 and Alzheimer disease: CSF GAP-43 was correlated with CSF Aβ42 in MCI ε4+ and AD ε4− groups (rs = −0.306, p < 0.001; rs = 0.379, p = 0.016; respectively), but there were no similar significant relationships found in CN ε4−, CN ε4+, MCI ε4−, and AD ε4+ groups (rs = 0.078, p = 0.312; rs = 0.056, p = 0.649; rs = −0.094, p = 0.180; rs = −0.078, p = 0.498; respectively) (Table 2 and Figure 2A).