In thiscase, mass spectrometry also revealed the presence, location, andcomposition of Fab glycosylation in the heavy chain of the M-protein.While the Fab-profiling workflow presented here is limited to theIgG1 subclass, and the de novo sequencing and glycanprofiling methods are best suited for research applications, we believethat a robust implementation of Fab profiling across all IgG subclassesby LC-MS holds promise for the clinical detection of M-proteins anddiagnostics of monoclonal gammopathies. The gene discussed is MYOM2; the disease is monoclonal gammopathy.