14 patients with irMG complicated with myositis and myocarditis, the frequencies of HLA-DQB1*03:03 (35.7% vs. 15.9%) and HLA-C*01:02 (35.7% vs. 15.9%) were significantly higher than those in the normal population (P = 0.016, OR = 2.994, 95% CI = 1.378–6.506). The gene discussed is HLA-DQB1; the disease is myositis disease.