Elevated expression of beta-site amyloid precursor protein cleaving enzyme 2 in brains of patients with Down syndrome.

The gene encoding the beta-site amyloid precursor protein cleaving enzyme 2 (BACE2) has been determined to be located on the long arm of chromosome 21 at 21q22.3. BACE2 cleaves the amyloid precursor protein at the beta-secretase site and is thought to contribute to amyloid beta protein production. In the present study, changes in the expression of BACE2 were investigated immunohistochemically in the frontal cortex of patients with Down syndrome (DS). The immunoreactivity for BACE2 was detected in neurofibrillary tangle-bearing neurons from the elderly DS brains with Alzheimer-type neuropathology, but were not detected in those of DS brains without Alzheimer-type neuropathology or of control brains of any age. This suggests the possibility that the elevated expression of BACE2 is involved in the Alzheimer-type neuropathology of DS.