[Quantitative Detection and Integrality Analysis of Plasma Circulating Cell-Free DNA in Multiple Myeloma].

Objective: To investigate the role of plasma circulating cell-free DNA (cf-DNA) in the screening and diagnosis of patients with newly diagnosed multiple myeloma (MM) and explore the changes of cf-DNA in terms of content and integrality in the assessment of disease in patients treated with chemotherapy.

Methods: Peripheral blood specimens were collected from 35 newly diagnosed MM patients and 18 healthy volunteers, and 13 of the 35 patients who had finished 3 courses of standard induction chemotherapy were selected as follow-up group. The ALU247 and ALU115 fragments were used as the target genes, and the cf-DNA content in the plasma of patients and healthy controls was measured by quantitative polymerase chain reaction (qPCR). The integrality of cf-DNA was calculated by the ratio of ALU247 to ALU115.

Results: Both the concentration of ALU247 and ALU115 fragments and the integrality of cf-DNA in patients were significantly higher than those in healthy controls (all P < 0.05). Patients who had underwent 3 courses of induction chemotherapy had significantly decreased concentration of ALU247 and ALU115 fragments and integrality of cf-DNA after treatment (all P < 0.05), and strong positive correlations were manifested between cf-DNA integrality and serum M protein content, as well as proportion of abnormal plasma cells in bone marrow before and after treatment (r =0.703, 0.705).

Conclusions: Cf-DNA has certain positive significance for the screening and diagnosis of MM. Furthermore, cf-DNA may be a synergism or alternative to serum M-protein content and proportion of abnormal plasma cells in bone marrow in assessing the condition, curative effect and prognosis of patients.