NPTX2, also known as neuronal activity-regulated protein, has been reported to have reduced CSF levels in various neurodegenerative diseases such as AD (22), genetic frontotemporal dementia (FTD) (23), and dementia with Lewy bodies (DLB) (24), correlating with cerebral atrophy and cognitive dysfunction (33). Here, NPTX2 is linked to Alzheimer disease.