Linear discriminant effect size analysis showed that 52 bacterial taxa (22 psoriasis and 30 periodontitis) and 21 bacteria taxa associated with the healthy control differentiated the salivary microbiota of patients with psoriasis from that of orally healthy patients with periodontitis. Significantly lower mean salivary levels of NGAL (psoriasis: 996, periodontitis: 2072, controls: 2551 ng/mL) and transferrin (psoriasis: 4.37, periodontitis: 7.25, controls: 10.02 ng/mL). The gene discussed is LCN2; the disease is periodontitis.