IGHA1 and cardiomyopathy-hypotonia-lactic acidosis syndrome: We conducted a mass spectrometry-based analysis to identify and compare the glycan structures of serum IgA1 in this patient, disease control patients with monoclonal IgA plasma cell disorder (MPCD) accompanied by multiple myeloma and monoclonal gammopathy of undetermined significance without renal involvement, and healthy volunteers (HV).