Vitamin D Receptor FokI Gene Polymorphism in Rheumatoid Arthritis Patients

Abstract

Background: Rheumatoid arthritis (RA) is a chronic, systemic, destructive joint disease. Vitamin D initiates biological responses via binding to the vitamin D receptor (VDR), which is a member of the steroid hormone receptor superfamily located on chromosome 12 (12q12-q14) that regulates gene expression in a ligand-dependent manner. The receptor (VDR) is active in almost all tissues that are necessary for the effects of vitamin D.
Objective: The present work aimed to detect vitamin D receptor FokI gene polymorphism in rheumatoid arthritis patients, to assess its role as a risk factor of the disease.
Patients and Methods: A case-control study was conducted on 44 subjects (22 RA patients and 22 apparently normal volunteers age and sex-matched with patients) at the Clinical Pathology, Rheumatology and Rehabilitation Departments, Faculty of Medicine, Zagazig University.
Results: Serum vitamin D level was found to be significantly lower among RA patients compared to healthy controls. There was a significant difference between the studied groups regarding VDR FOK1 gene polymorphism and its alleles. There was a non-significant difference between the different genotypes regarding age, however, the difference between them was significant regarding sex as it was noticed that FF and ff homozygous genotypes were found only in females compared to their male counterparts while Ff heterozygous genotype was found equally among both males and females.
Conclusion: Vitamin D receptor gene FokI polymorphism could be considered as genetic risk markers of RA susceptibility, associated with vitamin D level deficiency which was found to be significantly lower among FF genotype compared to other genotypes. Having FF and Ff genotypes have almost a higher risk than having ff genotype to be RA patient.