To understand the clinical utility of a live cell-based assay (CBA) for testing of acetylcholine receptor antibodies (AchR Ab) in serum for the diagnosis of myasthenia gravis (MG). To determine the specificity, sensitivity and robustness versus the radioimmunoprecipitation assay (RIPA)

A significant proportion of MG patients do not have detectable AchR Ab or muscle-specific tyrosine kinase antibodies by radioimmunoprecipitation (RIPA). This poses an increased problem as more effective therapies are accessible that demand antibody positivity to be reimbursed. A live CBA that involves expressing clustered AchR on the cell surface through the co-expression of intracellular anchoring protein rapsyn has demonstrated the ability to detect AchR Ab in 16% to 60% of seronegative MG patients.

470 serum samples from well characterized myasthenia gravis patients where assayed. 130 of these patients where double seronegative for Acethylcholine and MuSK antibodies by RIPA.

The AchR Ab test by CBA is a highly sensitive, specific and reproducible assay. It has shown to improve diagnostic sensitivity of AchR Ab in Adults with MG.