Association of HLA DRB1-DQB1 Haplotypes with the Risk for Neuromyelitis Optica among South Indians.

Background:Neuromyelitis optica (NMO) is an autoimmune demyelinating disorder, mainly characterized by severe optic neuritis, transverse myelitis and the high levels of antibodies against NMO-immunoglobulin G (IgG) or aquaporin-4 (AQP4). HLA-DR and HLA-DQ alleles within the HLA class II region on chromosome 6p21 are known to play a significant role in several autoimmune diseases including NMO. The rationale of the current case-control study is to explore the association of HLA-DRB1 and HLA-DQB1 alleles with the risk of NMO and its association with the clinical and serological markers. Methods:A total of 158 samples (38 NMO cases and 120-age and ethnicity matched controls) were genotyped for the HLA-DRB1 and HLA-DQB1 alleles by using PCR-SSP method. Results:Our analysis showed significant association of HLA-DRB1*10 allele (OR 2.63, 95% CI: 1.18-5.83, p=0.02) with NMO whereas DRB1*14 showed protective role against NMO (OR 0.33: 95% CI: 0.11-0.94, p=0.043). HLA-DRB1*10 allele also showed significant association in patients with NMO-IgG positive antibody (OR 3.28: 95% CI: 1.42-7.5, p=0.006). There was no association of HLA DQB1 alleles with NMO and also with NMO-IgG antibody. Among the haplotypes groups, HLA-DRB1*10-DQB1*05 (OR 2.61, 95% CI: 1.11-6.1, p=0.03), HLA-DRB1*15-DQB1*03 (OR 4.5, 95% CI: 1.81-11.5, p=0.001) were strongly associated with the risk of NMO, whereas DRB1*14-DQB1*05 (OR 0.20, 95% CI: 0.060-0.721, p=0.008) showed negative association with NMO. Conclusion:From this study, it is concluded that the HLA-DRB1*10 and DRB1*10-DQB1*05 and HLA-DRB1*15-DQB1*03 haplotypes may influence the susceptibility to NMO among the South Indians. Additionally we found DRB1*14 allele and DRB1*14-DQB1*05 haplotype showed protective role for NMO.