OBJECTIVES Behçet's disease (BD) may be triggered by infectious agents in genetically susceptible persons. Human β-defensin 2 is an inducible antimicrobial peptide, the level of which can be influenced by copy number (CN) of the DEFB4. We investigated the relationship between copy number variation (CNV) of DEFB4 and BD.

METHODS One hundred and ninety-seven patients with BD and 197 healthy controls were enrolled. After measuring CN of DEFB4 with a paralogue ratio test, the CNV was compared between patients and controls. CNV was also analysed in comparison with the clinical manifestations of BD.

RESULTS The CN of DEFB4 was unimodally distributed among the study subjects with mean CN of 4.57 and standard deviation of 1.28. BD samples had numerically lower CN than controls, but the difference was not statistically significant (4.49 ± 1.21 vs. 4.65 ± 1.36, p=0.245). Regarding the relationship between CN of DEFB4 and clinical manifestations, there was no difference of CNV depending on the clinical manifestations.

CONCLUSIONS We found no significant difference in CNV of DEFB4 between patients with BD and controls. Our results suggest that CNV of DEFB4 may not contribute to the pathogenesis of BD.