Mutations in NTN1 (netrin-1) and DCC in humans have been associated with several dopamine-associated psychiatric conditions, including neurodevelopmental disorders such as schizophrenia (Wang et al., 2018; Tang et al., 2019; Grant et al., 2012) and major depressive disorder (Tang et al., 2019; Zeng et al., 2017; Vosberg et al., 2020; Torres-Berrío et al., 2020), as well as multiple neurodegenerative disorders (Lesnick et al., 2007; Lesnick et al., 2008; Lin et al., 2009). Here, DCC is linked to major depressive disorder.