This gene encodes an epididymal protease inhibitor, which contains both kunitz-type and WAP-type four-disulfide core (WFDC) protease inhibitor consensus sequences. Most WFDC genes are localized to chromosome 20q12-q13 in two clusters: centromeric and telomeric. This gene is a member of the WFDC gene family and belongs to the telomeric cluster. The protein can inhibit human sperm motility, and polymorphisms in this gene are associated witHuman, Mouseale infertility. Read-through transcription also exists between this gene and the downstream WFDC6 (WAP four-disulfide core domain 6) gene.