On the base of our study, as smoking subjects also had lower levels of IgA, IgG, and IgM in their saliva than non-smoking subjects, despite the fact that there is little evidence that the salivary Igs have a protective action against periodontitis and that the whole saliva does not result in whole from the salivary glands, it can be concluded that the deteriorated periodontal health conditions of these patients can be attributed in part to a lowering of the host’s defense due to a decrease in the quantity of Igs in salivary fluid. The gene discussed is CD79A; the disease is periodontitis.