1. To carry out research on minimal residual disease (MRD) monitoring in patients with multiple myeloma (MM) based on plasma circulating tumor DNA (ctDNA) methylation sequencing, which aims to explore new MRD detection methods for MM;
2. Carry out ctDNA-based methylation sequencing in newly diagnosed, remission, and, relapsed MM patients, to track the clonal evolution patterns; and explore the in the initial diagnosis-remission-relapse stage of MM, track the clonal evolution characteristics of methylation profiles in MM patients during the disease progression.

Inclusion Criteria:

- For myeloma patients: i) Age no less than 18 and no more than 75; ii) Diagnosed with symptomatic multiple myeloma according to IMWG consensus; iii) Provide informed consent in accordance with the declaration of Helsinki.

- For healthy controls: i) Age no less than 18 and no more than 75; ii) Provide informed consent in accordance with the declaration of Helsinki.

Exclusion Criteria:

- For myeloma patients: i) Insufficient amount of peripheral blood obtained; ii) Methylation sequencing failed due to technical reasons.

- For healthy controls: i) Insufficient amount of peripheral blood obtained; ii) Methylation sequencing failed due to technical reasons.

For patients aged between 18 and 75, and diagnosed with symptomatic multiple myeloma according to IMWG consensus will be included in this study.

The datasets generated during and/or analysed during the current study are available from the corresponding author at angang@ihcams.ac.cn on reasonable request.