FZD4, a member of the frizzled gene family located on human chromosome 11q14.2, was first isolated from a human gastric cancer cDNA pool in 1999. It contains two exons and encodes a 537-amino acid protein with a seven-transmembrane domain. Acting as a receptor in the Norrin/Wnt signaling pathway, FZD4 is involved in cell signal transduction, cell proliferation, and cell death and is essential for the development of the retinal vascular system.reported that FZD4 mutations accounted for 15.2% of FEVR patients, while in our previous study, FZD4 mutations were detected in 21% of FEVR families. According to the Human Gene Mutation Database, the mutation types of FZD4 include nonsense mutation, missense mutation, small deletion, small insertion, gross deletion, and complex rearrangement.