Clinical features of myasthenia related with autoantibodies to muscle specific tyrosine kinase (MuSK)

: Anti-acetylcholine receptor antibodies are detected in 80 to 90% of patients with generalized myasthenia gravis - seropositive myasthenia gravis (SPMG). Approximately 10% to 20% of patients with autoimmune MG do not have antibodies to acetylcholine receptor (AChR) - seronegative MG (SNMG). An immunological study of the blood serum of patients with SNMG revealed patients with or without antibodies to muscle specific tyrosine kinase (MuSK+ and MuSK-, respectively). A clinical study of 13 MuSK+ patients with myasthenia showed that this group was characterized by predominant affect of mimic and bulbar muscles with the rare involvement of eye movement and body muscles. In Musk+ patients with myasthenia, the clinical efficacy of antitoxin esterase drugs was minimal or absent. No unequivocal conclusion on the clinical pattern of this form of myasthenia has been made.