Fig. 2
Serum protein and genetic characterization of the case and lymphocyte counts in reported cases of mu heavy chain disease. A Serum immunoelectrophoresis identified a monoclonal protein composed of kappa light chains with a possible faint band at IgM. B The serum immunoglobulin-enriched matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MASS-FIX) and monoclonal immunoglobulin rapid accurate mass measurement IgM spectra for the patient demonstrating a 26,320 Da fragment of IgM heavy chain. Upper left panel: MASS-FIX IgM spectra demonstrating 3 M-proteins (An IgM kappa plus free kappa plus a suspected IgM heavy chain). Upper right panel: MASS-FIX IgM spectra for a healthy donor. Lower left panel: An LC-ESI-Q-TOF of the suspected IgM fragment for the + 11 charge state. Lower right panel: Fragmentation spectra of the suspected IgM heavy chain, demonstrating a pattern consistent with an IgM heavy chain. C Array comparative genomic hybridization revealed a 6q deletion. D Absolute lymphocyte count of mu heavy chain disease cases previously reported in the literature and including this case, plotted on a log scale. Dashed line indicates 5 × 109/L threshold for lymphocytosis. Abbreviations: LC-ESI-Q-TOF: liquid chromatography coupled with electrospray ionization quadrupole time of flight mass spectrometry