MAPT and Alzheimer disease: Previous studies have indicated that plasma phosphorylated tau 217 and phosphorylated tau 181 could differentiate AD from FTD (Thijssen et al., 2020, 2021), while a few studies suggested potential biomarkers only on diagnosis of HD without reporting the differential effect from AD (Wild et al., 2008; Battaglia et al., 2011; Caron et al., 2022).