Chronic periodontitis (ChP) is a multifactorial disease influenced by microbial and host genetic variability; however, the role of beta-defensin-2 genomic (DEFB4) copy number (CN) variation (V) in ChP remains unknown. The association of the occurrence and severity of ChP and DEFB4 CNV was analyzed. Our study included 227 unrelated Caucasians, that is, 136 ChP patients (combined ChP) and 91 control individuals. The combined ChP group was subdivided into the severe ChP and slight-to-moderate ChP subgroups. To determine DEFB4 CNV, we isolated genomic DNA samples and analyzed them by relative quantitation using the comparative CT method. The serum beta-defensin-2 (hBD-2) level was determined via ELISA. The distribution pattern and mean DEFB4 CN did not differ significantly in combined ChP cases vs. the controls; however, the mean DEFB4 CN in the severe ChP group differed significantly from those for the control and slight-to-moderate ChP groups. Low DEFB4 CN increased the risk of severe ChP by about 3-fold. DEFB4 CN was inversely associated with average attachment loss. Mean serum hBD-2 levels were highest in the controls, followed by the slight-to-moderate ChP group and the severe ChP group. The results suggested an association between decreased DEFB4 CN and serum hBD-2 levels and periodontitis severity.
Keywords: biomarkers; case-control studies; gene dosage; genetic polymorphism; molecular genetics; periodontal diseases.