In contrast, another investigation found no differences between PCSK9 concentrations in CSF of AD and non-AD individuals; however, PCSK9 levels increased both in AD and non-AD subjects affected by other neurodegenerative processes, and also correlated with total tau levels, pointing to a general PCSK9 involvement in various neurodegenerative diseases [132]. The gene discussed is PCSK9; the disease is Alzheimer disease.