Nucleic acid from saliva and salivary cells for noninvasive genotyping of Crohn's disease patients

CARD15 genes carrying the 3020insC frameshift polymorphism encode a truncated CARD15 protein that is unresponsive to bacterial muramyl dipeptide, and are strongly associated with increased susceptibility to Crohn's disease (CD). In this study we established that CARD15 gene sequences encompassing the major 3020insC polymorphism could be readily amplified from the DNA found in saliva. In addition, CARD15 RNA sequences can be readily derived from the cellular component of saliva, which is primarily comprised of buccal epithelial cells. Our results demonstrate that saliva is a readily accessible source of DNA and RNA for genotyping CD patients for variants of the CARD15 gene, representing an alternative source of nucleic acid to that obtained from venous blood.