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 105, DEFB105A and DEFB105B, in tail-to-tail orientation. This gene, DEFB105A, represents the more centromeric copy.[7]
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Boniotto M, Ventura M, Eskdale J, et al. (2005). "Evidence for duplication of the human defensin gene DEFB4 in chromosomal region 8p22-23 and implications for the analysis of SNP allele distribution". Genet. Test. 8 (3): 325–7. doi:10.1089/gte.2004.8.325. PMID15727258.