ASSOCIATION BETWEEN HLA-DRB1 ALLELES AND SUSCEPTIBILITY TO RHEUMATOID ARTHRITIS AND TREATMENT RESPONSE.

Background and Objectives: Rheumatoid arthritis is an autoimmune disease with poorly understood pathophysiology. Genetic component of disease etiology, especially human leukocyte antigen (HLA) association, is well known. Ethnic differences account for a number of variations in disease association with the HLA locus and there seem to be differences in various studies regarding the role of HLA in genetic predisposition to disease. This work was aimed to study Human Leukocyte antigen HLA-DRB1 alleles association with susceptibility to rheumatoid arthritis and relation between certain alleles and response to treatment. Patients and methods: The study included 48 rheumatoid arthritis (RA) patients diagnosed on the basis of criteria established by the American College of Rheumatology(ACR), and 48 sex matched healthy volunteers as a control group. HLA-DRB1 Typing using Luminex X-Map technology was done for all patients and controls. Results: frequency distribution of HLA-DRB1 alleles was compared between patients and controls, a significant difference was demonstrated as regards frequency of HLA-DRB1*04 and HLA-DRB1*16 alleles being higher among patients compared to controls. HLA-DRB1*04, *13 alleles were significantly associated with high disease activity. HLA-DRB1*15 and DRB1*11 alleles were significantly associated with good response to treatment in the form of disease modifying antirheumatic drugs (DMARDs) , while HLA-DRB1*04, DRB1*01 and DRB1*16 alleles were significantly more common among non responders to treatment or deteriorated patients. Conclusion: Our study suggests that HLA-DRB1*04 and DRB1*16 alleles are susceptibility alleles to RA. HLA-DRB1*04 and *13 may be of prognostic value as they were significantly associated with high disease activity indicating a high risk for developing a more active type of the disease. HLA-DRB1* 11, *15, *04, *01 and *16 may be predictors for response to treatment.