Influence of HLA on progression of optic neuritis to multiple sclerosis: results of a four-year follow-up study

Background: Genetic predisposition in multiple sclerosis ( MS) has always been a critical concern in aetiology and progress of the disease. The present study looks into the relations between human leukocyte antigen (HLA), optic neuritis ( ON) and MS in the Iranian population. Methods: Patients with potential diagnosis of acute ON underwent a standardized clinical examination for confirming the diagnosis. Selected patients were gathered for HLA typing and clinical follow up. Results: Of the 55 patients, 46 (83.6%) were female. The mean age was 25( +/- 7.3) with a range of 12 - 43. Twenty of the 55 (36%) were confirmed for the diagnosis of clinically definite MS (CDMS). Results show that A23, B21, A11 and B51 alleles were present in 4 (20%), 6 (30%), 2 (10%) and 1 (5%) of the CDMS patients, respectively. Ten (50%) and 17 (85%) CDMS patients were positive for HLA class II alleles, DR2 and DQ1, correspondingly. Conclusions: The study strongly suggests the association among DR2, A23 and B21 allele and the evolution of ON to MS. High prevalence of A23 and DR2 alleles in CDMS patients compared with the normal population may suggest an important role for these alleles in the development of MS. The study suggests B51 as a protective factor against development of ON in the normal population. In addition, results do not confirm previous studies considering A11 as a predisposing factor. The present study finally evokes that different classes of HLA have different roles in susceptibility to MS and confirms disease heterogeneity as an important emerging concept in MS.