Objectives: The aim of this study was to assess the possible the association between +3061 (G>A, rs1143676) missense mutation in exon 24 of the integrin α-4 subunit (ITGA-4) gene and the response to natalizumab in a sample of Iraqi multiple sclerosis patients. Methods: A sample of 59 patients with multiple sclerosis (16 males and 43 females; mean age of 32 years; age range of 15 to 52 years) receiving natalizumab for at least 12 consecutive months were involved in the study between March and August/ 2022. The sample was categorized into two groups according to their response to natalizumab treatment (responders and non-responders). Polymerase chain reaction and Sanger’s sequencing for the extracted deoxyribonucleic acid was performed to identify the polymorphism at ITGA-4 gene promoter region. Results: The 3061 AA and AG genotypes were present in both groups (responders and non-responders to natalizumab treatment) with the lack of the wild form GG genotype. The AG genotype was significantly present in the non-responders’ group and appeared to have a significant impact on the responsiveness to natalizumab by increasing the propensity of being non-responder with a positive correlation (Phi-coefficient of 0.294) on the contrary of AA genotype. Conclusion: The +3061 (G.A) missense mutation is related to the response to natalizumab in multiple sclerosis patients with the AG genotype, thereby increasing the likelihood of non-response significantly.
