The innate immune system includes antimicrobial peptides that protect multicellular organisms from a diverse spectrum of microorganisms. beta-Defensins comprise one important family of mammalian antimicrobial peptides. Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. Defensins are short, processed peptide molecules that are classified by structure into three groups: alpha-defensins, beta-defensins and theta-defensins. All beta-defensin genes are densely clustered in four to five syntenic chromosomal regions. Chromosome 8p23 contains at least two copies of the duplicated beta-defensin cluster. This duplication results in two identical copies of defensin, beta 106, DEFB106A and DEFB106B, in head-to-head orientation.