Italian biologists have looked retrospectively at the risk of obtaining ‘false positive’ autoantibody results when investigating patients suspected of having myasthenia gravis,
- the study was limited solely to autoantibodies directed against the acetylcholine receptor (anti-RACh)
- of the 4,795 tests carried out over the last 20 years and revisited for the purpose, 50 true ‘false-positives’ were identified,
- the final diagnoses of certainty were very varied, ranging from purely ophthalmological problems (strabismus, spontaneously resolving dipoplia, other) to functional problems,
- alternative assay methods were used in six patients, proving that their anti-RACh autoantibodies were negative.
Even if this situation only concerns a very small number of individuals, the validity of this assay should be questioned in the event of incongruities.
