For example, in 2021, Liu observed increased levels of ABCA1-labeled exosomal miRNA-135a in the CSF of the AD group compared to those of the control group (P < 0.05) and significantly increased levels in mild cognitive impairment (MCI) and dementia of Alzheimer-type (DAT) patient groups compared to those of the control group (P < 0.05; Liu C. G. et al., 2021). This evidence concerns the gene ABCA1 and Alzheimer disease.