Pediatric myasthenia gravis with a combination of AChR and RyR is associated with an earlier onset and lower CSR rate: A cohort study in southwest China

Abstract

BackgroundThe clinical manifestations and prognosis of myasthenia gravis are related to antibodies, and children are affected differently than adults. The presence of ryanodine receptor and titin antibodies in adults indicates late onset and severe disease related to thymoma, but their role in children is rarely reported. MethodsThis study collected a cohort of children according to inclusion and exclusion criteria, consisting of antibody-negative, AChR-positive, and AChR with or without titin and RyR antibodies. The differences among groups in general conditions, clinical manifestation, treatment and prognosis were compared. ResultsIn total, 171 patients were included: 33 patients (19.30%) were antibody-negative, 84 patients (49.12%) were positve for AChR antibody, 22 patients (12.87%) were positve for AChR and RyR antibodies, 5 patients (2.92%) were positve for AChR and Titin antibodies, and 27 patients (15.79%) were positve for AChR, RyR and Titin antibodies.The median onset age of all the patients was 57.8 (9–177) months, and patients with AChR and RyR antibodies (p = 0.02) and AChR, RyR and Titin antibodies (p = 0.0006) had a younger onset age than patients with AChR antibodies. The rate of generalized MG and MG-ADL before treatment in the AChR-, RyR- and Titin antibody-positive groups was distinctly higher than that in the AChR antibody-positive group (p = 0.038, p = 0.0325). The rate of IVIG use in the AChR-, RyR- and Titin antibody-positive groups (p = 0.0388) was higher than that in the AChR antibody-positive group. The rate of immunosuppressant use in the AChR and RyR antibody-positive group (p = 0.0415) and in the AChR, RyR and Titin antibody-positive group (p = 0.0006) was higher than that in the AChR antibody-positive group. Plasmapheresis was performed in 1 case in the AChR-, RyR- and Titin antibody-positive groups. The CSR rate in the AChR and RyR antibody-positive group (p = 0.0423) and in the AChR, RyR and Titin antibody-positive group (p = 0.0152) was significantly lower than that in the AChR antibody-positive group. Gender, ptosis severity, and CSR time were not significantly different between groups. ConclusionsWe summarized one of the largest cohorts of pediatric MG patients and compared the clinical phenotype of patients with antibody-negative, AChR-positive, and AChR with or without titin and RyR antibodies. The results showed that patients with AChR and RyR antibodies had a younger onset age, a higher immunosuppressant use rate and a lower CSR rate.