An elevated serum κ free light chain (FLC) may be a biomarker for individuals with myasthenia gravis (MG) who are double serum negative (SN-MG).
Why this matters
MG is an antibody-mediated autoimmune disease which affects striated skeletal muscles and can lead to localized ocular muscle weakness. Most individuals with MG are diagnosed through a series of tests for specific antibodies which includes acetylcholine receptors (AChRs), muscle-specific kinase (MuSK) and lipoprotein receptor-related protein 4 (LRP4). However, 10% of individuals with MG have no detectable autoantibodies and are considered serum negative (SN-MG) making diagnosis for these individuals difficult. Overproduction of FLC has been implicated in autoimmune diseases and may serve as a biomarker for MG. The results of this study will impact individuals with SN-MG by providing them with a possible biomarker to aid with their diagnosis.