Diffuse plaques in the cerebellum and corpus striatum in Down's syndrome contain amyloid beta protein (A beta) only in the form of A beta 42(43).

The diffuse amyloid (A beta) plaques of the cerebellum and corpus striatum were examined in 32 patients with Down's syndrome, ranging in age from 9 to 71 years, using the end-specific monoclonal antibodies BA27 and BC05 to detect A beta species terminating at amino acids 40 and 42(43) respectively. When present, the diffuse plaques of both regions contained only A beta 42(43) at all ages. A beta 40 was, however, present along with A beta 42(43) in the few cored plaques that were occasionally present in the Purkinje and molecular cell layers of the cerebellum of some of the more elderly patients. It is concluded that diffuse plaques of the cerebellum and striatum contain only A beta 42(43) and that, in contrast to those of the cerebral cortex, these do not "mature' during their lifetime into A beta 40 containing plaques.