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

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.

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.

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).

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.