DEFB1,Beta-defensin 1, is a protein that in humans is encoded by the DEFB1 gene. DEFB1 belongs to the defensin family. Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. The DEFB1 gene spans more than 7 kb and includes a large 6,962-bp intron.By 2-color fluorescence in situ hybridization on both metaphase chromosomes and released chromatin fiber, the DEFB1gene is mapped to 8p23.2-p23.1, within 100 to 150 kb of the gene for human neutrophil defensin-alpha-1. DEFB1may augment neonatal host defenses through antimicrobial effects or prime the adaptive immune system at mucosal surfaces.