25-hydroxyvitamin D3 deficiency and vitamin D receptor polymorphisms in Egyptian patients with Behçet’s disease: a pilot study

Background: We investigated serum levels of 25-hydroxyvitamin D3 and the vitamin D receptor (VDR) gene polymorphisms (Fokl, Bsml) in Egyptian patients with Behçet’s disease (BD) and their relationship to disease manifestations and activity. Methods: We studied 45 patients with BD fulfilling the international study group criteria ISG for BD (1999) and 45 healthy, matched controls. We evaluated VDR Fokl, BsmI gene polymorphisms using polymerase chain reaction and restriction enzyme cleavage. Findings: The serum levels of 25-hydroxyvitamin D3 were lower in BD group than control group (P=0.006). When the BD group was compared to the control group, vitamin D3 deficiency (<20 ng/ml) was 6.7% vs. 0%; respectively (P=0.012), and vitamin D3 insufficiency (2030 ng/ml) was 77.6% vs. 60%; respectively (P=0.012). Among BD group, Bsml genotype was more associated with BD than FokI genotype. Furthermore, Bsml genotype frequencies were homozygous BB (33.3%) and heterozygous Bb (60%). There was no significant relation between 25-hydroxyvitamin D3 levels and active clinical manifestations of BD. Also, we did not detect any correlation between 25-hydroxyvitamin D3 levels and disease activity, or duration of illness. Bb and Ff genotypes were associated with vitamin D3 deficiency and insufficiency in BD group (P<0.001, 0.001 respectively). Conclusion: lower serum level of 25-hydroxyvitamin D3 might be a modifiable risk factor or consequence of BD. Polymorphisms in the VDR gene also are associated with susceptibility to BD which could be related to the immunomodulatory action of vitamin D. Further larger cohorts for genome wide association studies are required.