The Vitamin D receptor gene (VDR) polymorphisms are the candidate genetic variants for susceptibility to autoimmune diseases. In the present study, the investigators aimed to assess the association between VDR polymorphisms and myasthenia gravis (MG) susceptibility and disease features in Chinese Han population.The patients with MG and healthy controls were genotyped for VDR rs1544410, rs2228570, rs731236, and rs7975232 polymorphisms using the improved multiple ligase detection reaction. Information on age at onset, acetylcholine receptor antibody (AChR-Ab) and muscle-specific kinase antibody (MuSK-Ab) status, thymus status, involved muscles at onset and Osserman type at the maximum worsening during 2 years follow-up were obtained and used as the grouping basis of sub-classifications. Intergroup comparisons of allele and genotype frequencies, haplotype distributions were performed between MG group and the control group, and between each pair of MG subgroups.