SYNJ1 and Down syndrome: Apart from being a potential drug target for Alzheimer’s disease, Down syndrome, and TBC1D24-linked epilepsy, loss-of-function mutations in Synj1 also lead to disease, including epilepsy and Parkinson’s disease (Hardies et al., 2016; Xie et al., 2019; Taghavi et al., 2018; Hong et al., 2019; Bouhouche et al., 2017).