Background: NOD proteins are part of innate immunity mechanisms. They play a role in epithelial barrier functions and inflammatory responses to bacteria. Single nucleotide polymorphisms (SNPs) in the NOD1 gene have proven to be associated with inflammatory bowel disease (IBD) and asthma.
Objective: To investigate SNPs in the NOD1 gene in relation to aggressive periodontitis (AgP), a multifactorial, inflammatory disease of the supporting tissues of the teeth.
Materials and methods: Five SNPs in the NOD1 gene (4 intronic and 1 exonic) were tested for association in a total of 415 AgP patients and 874 controls both of Northern European ancestry.
Results: The frequencies of the rare SNP alleles ranged between 21% and 26% among cases, and 20-27% among controls, and were not statistically different between cases and controls. Two SNPs were in strong linkage disequilibrium (r(2) = 0.97 in cases and 0.94 in controls). The overall haplotype distributions did not differ between cases and controls. We observed 8 haplotypes with a frequency of >or=1% among cases and/or controls, but none of these haplotype frequencies differed significantly among cases and controls. Logistic regression analyses with adjustment for gender and smoking status did not reveal significant associations with AgP for any of the 5 SNPs. This study had a power of >or=95% to detect associations with variants carrying relative risks of >or=1.5 for heterozygote carriers and >or=2.25 for homozygote carriers.
Conclusions: Although SNPs in the NOD1 gene have been strongly associated with cases of IBD, the current study failed to show an association of NOD1 SNPs with AgP.