PTGFRN and Alzheimer disease: It has also been reported that more than 400 unique proteins mainly involved in AD, as well as the aging and telomere length pathway, were considerably enriched in CSF-derived EVs (Muraoka et al., 2019), and some proteins such as HSPA1A, NPEPPS, and PTGFRN could be used to monitor the progression of mild cognitive impairment (MCI) converted to AD (Muraoka et al., 2020).