See "A novel glycosylphosphatidylinositol-anchored form of ceruloplasmin is expressed by mammalian astrocytes"
by B.N.Patel and S.David, 'The GPI-anchored form of ceruloplasmin expressed by astrocytes is likely to be the major form of this molecule in the central nervous system because serum ceruloplasmin does not cross the blood-brain barrier. Lack of this form of ceruloplasmin in the central nervous system could lead to the generation of highly toxic free radicals, which can cause neuronal degeneration as seen in aceruloplasminemia and other neurodegenerative diseases such as Parkinson's and Alzheimer's disease'