Assessment of chromosome 19 for genetic association in sever chronic periodontitis

Background: A genome-association study is a powerful tool for analyzing small gene effects in complex diseases such as chronic periodontitis (CP), although the cost of analysis is prohibitive. We designed a study using the DNA pooling method, which could be a breakthrough in lowering such costs. This study was conducted to assess the genetic association in severe CP in a Japanese population. Methods: We adopted a DMA pooling method by genotyping 454 densely spaced microsatellite (MS) markers in chromosome 19 as a pilot study, with the possibility of future use in a whole-genome study. This can reduce the high cost and technical burden, which is generally unavoidable in a genomic association study. Pooled DNA samples from 300 case subjects, 300 control subjects, and 200 systemically healthy subjects were screened by genotyping MS markers. The case-control association in the candidate region was analyzed by individual typing of MS and single nucleotide polymorphisms (SNPs). Results: The single MS marker allele 17 of 1902G31 was isolated in association with severe CP (P= 0.0012 for 2x2; P<0.046 for 2 x m, where m refers to the number of polymorphic alleles observed in a population). No other SNP or MS polymorphism hypothesized to affect biologic functions in the critical region was found in the linkage disequilibrium block analysis. Conclusions: We efficiently isolated the susceptible locus for severe CP in chromosome 19 and identified a useful marker to evaluate the risk for disease. This approach can be applied to a whole-genome study in severe CP.