Association of HLA class II (DRB1, DQA1, DQB1) alleles and haplotypes with myasthenia gravis and its subgroups in the Iranian population.

Heterogenic pattern of HLA associations with myasthenia gravis (MG) among different ethnicities and also among different MG subgroups has been the subject of debate in large series of many studies. One hundred and sixty Iranian MG patients were investigated for HLA class II (DRB1, DQA1, DQB1) associations compared to two hundred healthy controls from the same ethnic population. DRB1*11 DQA1*0501 DQB1*0301 haplotype was found to be protective for total (ocular plus generalized) MG (Pc=0.005, OR=0.49) and generalized MG (Pc=0.008, OR=0.49). DRB1*04 DQA1*0301 DQB1*0302 haplotype (Pc=0.03, OR=2.25) was predisposing for anti-acetylcholine receptor (AChR) antibody-positive MG, while DRB1*16 DQA1*0102 DQB1*05 (Pc=0.013, OR=4.28) was predisposing for anti-muscle specific tyrosine kinase (MuSK) antibody-positive MG. There was also a trend of positive association for DRB1*14 DQA1*0104 DQB1*05 haplotype with MuSK-positive MG (Pc=0.054, OR=3.97). Among other MG subgroups and with less significance, DRB1*0101 DQA1*0101 DQB1*05 haplotype (P=0.016, OR=3.68) had positive association with pure ocular MG, and DRB1*03 DQA1*0501 DQB1*0201 haplotype (P=0.024) had negative association with thymomatous MG. This study highlights the importance of appropriate MG subgrouping according to clinical and paraclinical characteristics in HLA studies among MG patients.