Association of the ABCB1 C3435T Polymorphism with the Mixed Form of Ankylosing Spondylitis in the Algerian Population: A Case-control Study

Introduction: Ankylosing spondylitis (AS), also known as rheumatic pelvic spondylitis, is considered the primary condition in a group of chronic inflammatory rheumatic diseases collectively referred to as spondyloarthropathies. Objectives: This study aimed to explore the association between ABCB1 C3435T polymorphism and the predisposition to ankylosing spondylitis (AS) in the Algerian population. The frequency of this polymorphism was compared between the group of AS and healthy subjects. Methods: A case-control study involving 81 AS patients and 98 controls was conducted. DNA genotyping was done using predesigned probe-based allelic discrimination TaqMan® assays. Allele and genotype frequencies were compared between cases and controls, and statistical analyses were executed using SAS software (version 9.1, SAS Institute Inc., Cary, NC). Results: No statistically significant differences were observed in the frequencies of ABCB1 genotypes and alleles between AS cases and the control group. In contrast, the recessive model (CC+CT/TT) (OR = 8.99 [11.97-40.99], p = 0.004) was significantly associated with the mixed form of the disease, while the heterozygous 3435CT genotype provided protection against the axial form. Moreover, a positive association was also found between the ABCB1 C3435T polymorphism and BMI (OR: 5.19 [1.41-19.9], p = 0.01). Conclusion: This is the first study to explore the association of ABCB1 polymorphisms with susceptibility to ankylosing spondylitis in an Algerian population. It was determined that the ABCB1 C3435T SNP does not influence the risk of AS but rather affects the disease phenotype and body mass index (BMI).