Refractory myasthenia gravis: Characteristics of a portuguese cohort

ABSTRACT Introduction: Some myasthenia gravis (MG) patients are refractory to conventional treatments. Methods: To describe the clinical features of refractory MG (RMG) and explore the association with human leukocyte antigen HLA‐DRB1 alleles, a cohort study of 114 consecutive MG patients was performed. Patients were classified as RMG based on predefined criteria. Results: Twenty‐two patients were found to have RMG (19.3%). There were no differences between non‐RMG and RMG patients with respect to sex, age of onset, abnormal 3‐Hz repetitive nerve stimulation, anti‐acetylcholine receptor antibody positivity, thymectomy, thymoma or thymic hyperplasia, and polyautoimmunity. HLA‐DRB1*03 was more frequent in the non‐RMG vs. control population (P = 3 × 10−6). The HLA‐DRB1*13 allele was less frequent in non‐RMG patients compared with controls (P = 0.002), and less frequent in the non‐RMG group compared with the RMG group (P = 0.003). Discussion: HLA‐DRB1*03 was more common in non‐RMG, and the HLA‐DRB1*13 allele appeared to have a protective role, as reported previously in other autoimmune disorders. Muscle Nerve 60: 188–191, 2019