To assess the specificity of Aβ, NDP, COL6A2, APCS and APOE in relation to other small vessel diseases we performed additional IHC on cases that present various types of vascular defects, i.e., cotton wool plaque pathology, prion CAA, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), hypertension related small vessel disease and Cathepsin A-related arteriopathy with strokes and leukoencephalopathy (CARASAL). The gene discussed is APCS; the disease is CADASIL.