Novel hairpin-shaped primer assay to study the association of the -44 single-nucleotide polymorphism of the DEFB1 gene with early-onset periodontal disease.

A powerful, cost-effective new method for studying single-nucleotide polymorphisms (SNPs) is described. This method is based on the use of hairpin-shaped primers (HP), which give a sensitive and specific PCR amplification of each specific allele, without the use of costly fluorophore-labeled probes and any post-PCR manipulation. The amplification is monitored in real-time using SYBR Green I dye and takes only 2 h to yield results. The HP assay has a simple design and utilizes a conventional real-time PCR apparatus. The -44 C-->G transversion in the DEFB1 gene (which encodes human beta-defensin 1) has been previously associated with Candida carriage in oral epithelia. In this study, we analyzed the association between early-onset periodontal disease (EOP) and the -44 SNP. We used an HP assay to study the distribution of the -44 SNP in 264 human DNAs obtained from two cohorts of EOP patients and healthy controls from different ethnic backgrounds. The results indicate that the -44 SNP has a similar distribution between EOP and healthy patients, suggesting that it is not associated with the disease.