Interestingly, all four delta catenin proteins: ARVCF (Suzuki et al., 2009), catenin δ-1 (Hussman et al., 2011), catenin δ-2 (Turner et al., 2015), and plakophilin-4 (Hussman et al., 2011) are implicated in ASD or neurodevelopmental disorders. This evidence concerns the gene CTNND2 and neurodevelopmental disorder.