COL2A1 and Alzheimer disease: Conversely, 147 proteins were reduced in the CSF of Aβ+/tau- AD patients, including leucine-rich PPR motif-containing protein (LRPPRC), UDP-glucose 4-epimerase (GALE), collagen alpha-1(II) chain (COL2A1), and U5 small nuclear ribonucleoprotein 200 kDa helicase (SNRNP200).