Cell-free DNA in the plasma of patients with systemic sclerosis.

The aim of the present study was to evaluate the concentration of cell-free DNA (cf-DNA) in the plasma of patients with systemic sclerosis (SSc) and to examine the correlation of cf-DNA with clinical variables of the disease. The study population consisted of 122 SSc patients and 16 healthy controls. Epidemiological and clinical data were collected by direct assessment. The beta-globin gene was used to determine the total amount of DNA in the plasma by real-time quantitative PCR analysis. cf-DNA was found in all patients (mean concentration 1,420.7 copies/ml) and controls (mean concentration 1,462.5), with no significant difference. In SSc patients, no correlation was found between cf-DNA and the type of organ involvement, but patients with active disease presented significantly higher cf-DNA concentrations than those with inactive disease (p < 0.05). Our data suggest that cf-DNA could provide a useful biomarker for the assessment of disease activity in SSc patients.