Single Nucleotide Polymorphisms in the Human Beta Defensin-3 Locus

Beta-defensins are innate epithelial-derived antimicrobial peptides present in the oral cavity. One of these, human beta defensin 3 (HBD3) is inducible and possesses potent antimicrobial activity against microorganisms. Variation in expression of HBD3 may play a role in periodontal health and disease. Objectives: To assess and determine the presence of single nucleotide polymorphisms (SNPs) in the promoter and exon regions of HBD3. Methods: Buccal swabs were obtained from 16 periodontally healthy subjects and 8 periodontally diseased subjects. All subjects were 40+ years old, Caucasian non-smokers. Genomic DNA was extracted and the HBD3 promoter region, exon 1 and exon 2 were separately amplified via polymerase chain reaction. The products were purified and confirmed using gel electrophoresis prior to sequencing. Sequence results were analyzed using Accelrys SeqWeb. All sequence results were confirmed in both forward and reverse directions. Results: Two novel SNPs were identified at position -445bp and -537bp in the promoter region. No SNPs were identified in either exon 1 or exon 2 regions of HBD3 in this population. Conclusions: Absence of variation in exon 1 and exon 2 suggests that HBD3 is highly conserved among individuals in our population. Selective pressure to retain its identity suggests that HBD3 may play a significant role in health and disease. SNPs identified in the promoter region of HBD3 may be responsible for differential expression and/or regulation among individuals. Future studies will include a comprehensive investigation of the complete promoter region of HBD3 and the prevalence of SNPs in a larger population and among other ethnic groups. Funded by NIDCR RO1 DE13334.