Hereditary cerebral amyloid angiopathy

Cerebral amyloid angiopathies are defined by the presence of amyloid substa nce in the walls of cerebral vessels. All amyloid substances have a particu lar physico-chemical structure, which imparts certain specific staining pro perties, but the biochemical composition of different amyloid types varies. Different forms of cerebral amyloid angiopathy have been identified, based on the biochemical nature of the protein deposited (e.g. beta-amyloid, cys tatin C, transthyretin, gelsolin, amyloid protein Brl, prion protein). Some cerebral amyloid angiopathies are familial; these prompted genetic studies which in turn led to a better understanding of the genes coding for differ ent amyloid proteins. As a group, cerebral amyloid angiopathies have certain neuropathological le sions in common. Infiltration by amyloid substance results in weakening of the small vessel walls and secondary complications responsible for changes such as microinfarcts and miliary haemorrhages in the cerebral cortex, loba r haemorrhages and/or leucoencephalopathy. These changes form the basis of the neurological complications: meningeal and cerebral haemorrhages, transi ent ischaemic episodes, vascular dementia. However each type of hereditary cerebral amyloid angiopathy has individual clinical and histopathological f eatures reflecting the severity of arterial involvement, the extent of amyl oid deposition within or outside the central nervous system, and the associ ation with other neurodegenarative changes.