ABI3, ABI gene family member 3, is a member of a protein family that regulates the actin cytoskeleton (Sekino et al., 2015). A rare variant in ABI3, p.S209F (rs616338), is associated with an increased risk of Alzheimer’s disease (Sims et al., 2017; Conway et al., 2018; Olive et al., 2020; Bellenguez et al., 2022). Two common variants of ABI3, rs55978930 and rs16947151, were associated with levels of CSF tau at baseline and with cognitive function, respectively, in a set of ADNI subjects with MCI that progressed to Alzheimer’s dementia (Niu et al., 2019). The gene is highly expressed in microglia (Satoh et al., 2017), and ABI3 protein is also seen in neurons, where it may influence the shape of dendritic spines (Bae et al., 2012a; Bae et al., 2012b).