Autoantibodies against the acetylcholine receptor (AChR) and muscle-specific tyrosine kinase (MuSK) support the diagnosis of myasthenia gravis and have a pathogenic role in the disease. The autoimmune reaction occurs at the neuromuscular junction, impairing nerve impulse transmission. The hallmark symptom is exertional muscle weakness, asymmetrically affecting specific muscle groups.
Anti-AChR antibodies are highly specific for myasthenia gravis and are found in approximately 85% of patients. Early-onset cases mainly affect women under the age of 40, while late-onset cases (after 50) are more common in men. In approximately 20% of cases, this disorder is limited to the ocular muscles; however, in most patients, it evolves into a generalised form within a few years. Myasthenic crises can be life-threatening due to respiratory muscle weakness and dysphagia.
Approximately 6% of patients with myasthenia gravis are negative for anti- AChR antibodies: about one-third of the latter test positive for anti-MuSK antibodies, which are usually associated with a more severe disease course, predominantly affecting younger women.
Some patients affected by generalised myasthenia gravis test negative for both anti-AChR and anti-MuSK antibodies (double seronegative patients). In these cases, the disease may be caused by other rare autoantibodies.
In patients presenting typical symptoms, the diagnosis of myasthenia gravis is often based on autoantibody testing. Antibody levels against AChR and MuSK correlate well with the clinical picture, although they can vary significantly between individuals. In late-onset forms, the detection of anti-AChR antibodies helps in the differential diagnosis from other diseases with similar symptoms (such as amyotrophic lateral sclerosis (ALS), stroke, Lambert-Eaton syndrome and congenital myasthenic syndrome).
Myasthenia gravis is often associated with other autoimmune diseases. Additionally, approximately 20% of anti- AChR positive adult patients develop a thymoma.
Serum, EDTA plasma, heparin plasma, citrate plasma
IFA cells
Fasting for at least 8-12 hours before sampling
Refer to the Health Service Charter to check storage conditions
+2/+8°C
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