FZD4 and Familial exudative vitreoretinopathy: Mutations in the CTD of FZD4, that encompasses the K-T/S-XXX-W, a PDZ binding motif and S/T-X-V PDZ recognition motif, are associated with familial exudative vitreoretinopathy (FEVR), underscoring the functional importance of its unique structural features (Kondo et al., 2003; Fei et al., 2015; Seemab et al., 2019).