It is worth noting that the top five genes in the blood have been confirmed to be associated with AD, including HAL-DQB2, PLCALM, APH1B, CNN2, and CEACAM19 (Figure 2D; Logue et al., 2018; Seripa et al., 2018; Gockley et al., 2021; Park et al., 2021; Zhang et al., 2022b). Here, APH1B is linked to Alzheimer disease.