An Algorithm for Acetylcholine Receptor Antibody Testing in Patients with Suspected Myasthenia Gravis

Abstract

Myasthenia gravis (MG)1 is a well-characterized autoimmune disease with an estimated prevalence of 1 in 5000 individuals (1). The clinical presentation varies from mild weakness of limited muscle groups (class I or ocular MG) to severe weakness of multiple muscle groups (class V or severe generalized MG). Detection of autoantibodies to the neuromuscular nicotinic acetylcholine receptor (ACHR) has proved useful in assisting in the diagnosis of MG; however, the complexity of this disease, combined with the variety of antibodies associated with MG, has led to multiple attempts to correlate disease severity with antibody detection and concentration. In general, the ACHR antibody concentration is directly proportional to disease severity, but neither the presence nor the absolute concentration of ACHR antibodies correlates with disease severity in any individual patient. ACHR antibodies are specific for MG because they are not detected in healthy individuals or in patients with other autoimmune or neuromuscular disorders; however, their absence does not rule out disease, because only about 85% of confirmed MG patients with generalized disease possess ACHR antibodies(2)(3). ACHR antibodies are less frequently detected in MG patients with mild disease or restricted muscle weakness(2)(3). MG patients …