PKP4 and autism: Surprisingly, a high percentage of these targets (31%) are autism-associated proteins/genes, which include Dlg1, Dlgap2, Syn1, SynGap1, Ctnna1, and four delta catenin proteins (Ctnnd1, Ctnnd2, Pkp4, and Arvcf) (Yuan and Arikkath, 2017).