Recently, the ratio of myelin-associated glycoprotein to proteolipid protein-1 (MAG:PLP1, which represents chronic hypoperfusion) and the PDGFRB levels were shown to decline early with a positive correlation in the precuneus from post-mortem tissue of Alzheimer's disease and age-matched control brains[77]. The gene discussed is PDGFRB; the disease is Alzheimer disease.