For the DNMT3B polymorphism, the frequency of the T allele and the TT genotype respectively was higher in the periodontitis (52.9%; 27.5%) and in SLE (60.5%; 38.3%) groups compared to the control group (31.7%; 8.3%), even when the groups with inactive (67.5%; 40%) and active (55.5%; 37%) form of SLE were compared separately with the control group (p<0.05). The gene discussed is DNMT3B; the disease is periodontitis.