Gut Microbiome Studies in Patients With POEMS Syndrome and Other Plasma Cell Disorders

Inclusion Criteria: * Diagnosed with POEMS syndrome (newly diagnosed or in remission) or with newly diagnosed multiple myeloma (MM), monoclonal gammopathy of undetermined significance (MGUS), amyloid light chain (AL) amyloidosis or healthy controls from their households Exclusion Criteria: * Age under 18 years * Pregnancy * Substance abuse * Antibiotics use or gastrointestinal endoscopy in the 3 months prior to the study participation * Chronic gastrointestinal disorder * Gastrointestinal surgeries in the past 2 years * Chemotherapy (including anti-plasma cell treatment and steroids) or radiation treatment for cancer within the last 2 years or active cancer (other than plasma cell disorder)