The EMG/NCS results were normal; RNS disclosed a greater than 10% facial nerve decrement; AchRAB were negative; and anti-MUSK antibodies were elevated (0.09 NMOL/L); aquaporin and thyreoglobulin antibodies were normal; IgG4 levels were normal; vitamin B12 was low (173) and treated; chest CT showed no thymoma. This evidence concerns the gene MUSK and thymoma.