In a group of subjects with periodontitis with IL-1A-889 and IL-1B + 3953 genotype the total count of red complex (Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola), orange complex (Fusobacterium nucleatum, Peptostreptococcus micros, Prevotella intermedia, Campylobacter rectus) bacteria and of Campylobacter rectus has been found to be 3-fold and 2-fold higher than the negative genotype subjects [48]. Here, IL1A is linked to periodontitis.