Spectrum of amyloid beta-protein immunoreactivity in hereditary Alzheimer disease with a guanine to thymine missense change at position 1924 of the APP gene.

We studied neuropathologically 3 patients of a previously unreported kindred of presenile Alzheimer disease (AD), characterized by a G to T mutation at base pair 1924 (695 transcript) of the amyloid precursor protein gene. Classic features of presenile AD are observed. Neurofibrillary tangles with paired helical filaments as well as neuritic plaques are found in large number in neocortex and hippocampus. beta-Protein deposits in meningeal and parenchymal vessels are present, but not severe. Prominent subpial ribbon-like deposits are detected with antibodies to a 28-residue synthetic peptide; however, only occasionally can they be seen in thioflavin S treated sections. Along with a mild involvement of vessels, as demonstrated by beta-protein immunolabeling, parenchymal involvement is also seen in the cerebellar molecular layer. In the course of the study, we have not detected neuropathologic changes, which are mutation specific. Further investigations of familial Alzheimer disease with known genetic mutations will clarify whether correlations exist between specific mutations and neuropathologic phenotypes.