APP and cerebral amyloid angiopathy: HCHWA-D is an autosomal dominant disease that predominantly occurs in a limited number of families in the villages of Katwijk and Scheveningen in the Netherlands.8 A point mutation (E693Q) of the amyloid precursor protein (APP) gene9 leads to extensive Aβ deposition in the cortical and leptomeningeal arterioles and arteries.