Analysis of postmortem brain tissue of AD patients has revealed that the white matter is altered chemically, compared with that of patients without dementia: the amounts of total protein, myelin basic protein (MBP), myelin proteolipid protein (PLP), Cyclic nucleotide phosphohydrolase (CNPase), and cholesterol is significantly decreased, indicating a loss of myelin. The gene discussed is PLP1; the disease is Alzheimer disease.