Preliminary cross-sectional human PET studies in a wide range of ages are indicating that [18F]SMBT-1 is a selective MAO-B tracer with low non-specific binding, high entry into the brain while displaying favorable reversible kinetics, and have significantly higher binding in Aβ + AD (Figure 4) and Aβ + cognitively unimpaired controls (Villemagne et al., 2022), similarly to what has been reported with plasma GFAP (Verberk et al., 2020; Chatterjee et al., 2021). The gene discussed is GFAP; the disease is Alzheimer disease.