SOD1 and periodontitis: ALS1, ALS4, ALS6, ALS7, and ALS9 genes were identified in 100% (6/6) of the strains from patients with gingivitis, whereas in strains from patients with moderate periodontitis, the most frequent genes were ALS4 (65/66), ALS6, and ALS7 (64/66) in each case and ALS9 (63/66).