The direct measurement of amyloid proteins and other protein markers in cerebrospinal fluid (CSF) has been addressed in patients with sporadic CAA suggesting that measurement of beta-amyloid 1-40 (Aβ40), beta-amyloid 1-42 (Aβ42), total tau (t-tau), and phosphorylated tau 181 (p-tau181) in CSF might differentiate CAA from controls as well as from Alzheimer’s disease (AD) patients (Verbeek et al., 2009; Hernandez-Guillamon et al., 2012; Renard et al., 2012, 2016; Li et al., 2015; Martínez-Lizana et al., 2015; Charidimou et al., 2018; Banerjee et al., 2020). The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.