Myasthenia gravis, a rare disease, goes hand-in-hand with the production of autoantibodies directed against one of the parts of the neuromuscular junction, most often the acetylcholine receptor (AChR) or the muscle-specific tyrosine kinase (MuSK) receptor. Patients with AChR antibodies and those with MuSK antibodies form two distinct subgroups with regard to their symptoms and their treatment response.
Rare cases of positivity both to AChR antibodies and to MuSK antibodies have also been described. A team at the Canton Hospital (China) has compared 17 double seropositive patients to 27 patients with AChR antibodies and 8 patients with MuSK antibodies. The results of this single-centre retrospective study, published in March 2021, show that in comparison to patients with AChR antibodies, double seropositive patients have:
- more common bulbar involvement (47.1% versus 18.6%),
- a higher incidence of myasthenic crisis (41.2% versus 14.8%),
- a more severe MGFA score in the exacerbation phase,
- a greater need for immunosuppressants (58.8% versus 3.7%),
- less frequent remission (11.8% versus 55.6%).
This picture is similar to that of patients with MuSK antibodies in this study, something that was confirmed by a literature review (2005–2019) identifying 28 published cases of double seropositivity.
