Monoclonal gammopathy patients

(I) Inclusion Criteria:~1. Age 45 years or older.~2. Positive screening for monoclonal protein by MALDI-TOF MS.~3. Meeting the International Classification of Diseases, 11th Revision (ICD-11) criteria for one of the following disease types:Infectious diseases，Tumors，Blood or hematopoietic organ diseases，Immune system diseases，Endocrine, nutritional, or metabolic diseases，Nervous system diseases，Circulatory system diseases，Respiratory system diseases，Digestive system diseases，Musculoskeletal or connective tissue diseases，Urinary and reproductive system diseases.~4. Sufficient whole blood, plasma, serum, and stool samples available, with relevant case data provided.~(II) Exclusion Criteria:~1. History of intestinal tumors, irritable bowel syndrome, or inflammatory bowel disease, or diagnosed during hospitalization.~2. Antibiotic treatment in the past month.~3. Insufficient sample volume, or severe hemolysis, lipemia, jaundice, or other unqualified sample conditions.

Non-monoclonal gammopathy patients

(I) Inclusion Criteria:~1. Age 45 years or older.~2. Negative screening for monoclonal protein by MALDI-TOF MS.~3. Patients meeting ICD-11 criteria for one of the following disease types:Infectious diseases，Tumors，Blood or hematopoietic organ diseases，Immune system diseases，Endocrine, nutritional, or metabolic diseases，Nervous system diseases，Circulatory system diseases，Respiratory system diseases，Digestive system diseases，Musculoskeletal or connective tissue diseases，Urinary and reproductive system diseases.~4. Sufficient whole blood, plasma, serum, and stool samples available, with relevant case data provided.~(II) Exclusion Criteria:~1. History of intestinal tumors, irritable bowel syndrome, or inflammatory bowel disease, or diagnosed during hospitalization.~2. Antibiotic treatment in the past month.~3. Insufficient sample volume, or severe hemolysis, lipemia, jaundice, or other unqualified sample conditions.

Healthy control group

(I) Inclusion Criteria:~1. Age 45 years or older.~2. Negative screening for monoclonal protein by MALDI-TOF MS.~3. No significant diseases found upon medical examination, and confirmed not to have any diseases related to this study.~4. Sufficient whole blood, plasma, serum, and stool samples available, and relevant case data can be provided.~(II) Exclusion Criteria:~1. History of intestinal tumors, irritable bowel syndrome, or inflammatory bowel disease, or diagnosed during hospitalization.~2. Antibiotic treatment received in the past month. Presence of severe systemic diseases, including malignant tumors.~3. Insufficient sample volume, or presence of severe hemolysis, lipemia, jaundice, or other unqualified sample conditions.