Defensins are cysteine-rich cationic polypeptides that are important in the immunologic response to invading microorganisms. The antimicrobial protein encoded by this gene is secreted and is a member of the beta defensin protein family. Beta defensin genes are found in several clusters throughout the genome, with this gene mapping to a cluster at 20p13. The encoded protein is highly similar to an epididymal-specific secretory protein (ESP13.2) from cynomolgus monkey. Mutation of this gene is associated with impaired sperm function. [provided by RefSeq, Nov 2014].