MGUS or Monoclonal gammopathy of undetermined significance is a condition where an abnormal protein called monoclonal protein or M protein is produced in the body. There are a few synonyms that can be used to describe MGUS, such as benign monoclonal gammopathy, indolent monoclonal gammopathy, or smoldering myeloma. These terms are used interchangeably but they all refer to the same medical condition. MGUS is often asymptomatic and does not require any treatment. However, it may progress to multiple myeloma in some cases, and therefore, regular monitoring is necessary. Early detection and treatment of MGUS can help prevent the progression of the disease to multiple myeloma.