ABSTRACT
<p><b>OBJECTIVE</b>To determine the circular DNA level of patients with hand foot and mouth disease (HFMD) and evaluate its potential clinical value.</p><p><b>METHODS</b>Venous blood in 30 healthy children and 78 patients with HFMD within 3 days of onset of illness and convalescent period was collected. The level of plasma circular DNA was detected by duplex real-time polymerase chain reaction assay. Blood sugar, high-sensitive CRP(hs-CRP) and leucocyte were also detected.</p><p><b>RESULTS</b>The level of circular DNA in control group was (6.57 +/- 4.67) ng/ml. The level of circular DNA in ordinary and severe HFMD patients was (11.51 +/- 7.75) ng/ml and (20.59 +/- 10.67) ng/ml before treatment, respectively. The levels of circular DNA in ordinary and severe HFMD patients were significantly higher than that in control group (P = 0.021; 0.000); the level of circular DNA in severe HFMD patients was significantly higher than that in ordinary HFMD patients (P = 0.011). The level of circular DNA in severe HFMD patients after treatment were significantly lower than that before treatment (P = 0.033). The level of circular DNA before treatment and after treatment in ordinary HFMD patients had no significant difference. The levels of blood sugar and hs-CRP in severe HFMD patients were higher than those in ordinary before treatment (P = 0.045; 0.011). The levels of blood sugar and hs-CRP before treatment and after treatment in ordinary HFMD patients had no significant change. There was significantly positive correlation between the level of circular DNA and that of hs-CRP in HFMD patient (P = 0.021), but there was no correlation between the level of circular DNA and that of blood sugar and leucocyte.</p><p><b>CONCLUSIONS</b>The level of circular DNA not only become an early identification marker of severe HFMD patients, but also become monitoring marker of effect of treatment.</p>