Correlation of free fetal DNA with beta-human chorionin gonadotropin in circulation in pregnant women with high risk of Down's syndrome

Abstract

To investigate significance and correlation of free fetal DNA (fDNA) and beta-human chorionic gonadotropin (beta-hCG) in circulation in pregnant women with high-risk of Down's syndrome (DS). Pregnant women with a male fetus at second trimester screening for Down's syndrome were chosen, including 5 women with a trisomy 21 fetus (DS group), 21 women with DS high-risk pregnant women (DS high-risk group) matched with 22 normal pregnant women as control group. Free fDNA in maternal plasma were extracted. Male DYS14 gene was labled as fDNA, real-time PCR was used to detect fDNA expression. The concentration of beta-hCG in maternal serum was detected by chemiluminescence immune assay. The relationship between level of free fDNA and beta-hCG concentration was analyzed by Pearson correlation analysis. (1) The mean level of free fDNA was (127 +/- 58) GE/ml in DS group, which was significantly higher than (78 +/- 28) GE/ml in DS high-risk group and (48 +/- 21) GE/ml in control group,respectively (P < 0.01). When compared the level of free fDNA between DS high-risk group and control group, it reached statistical difference (P < 0.01). (2) The mean concentration of beta-hCG was (97 +/- 43) kU/L in DS group, which was significantly higher than (58 +/- 25) kU/L in DS high-risk group and (38 +/- 19) kU/L in control group, respectively (P < 0.01). The level of beta-hCG in DS high-risk group was also significantly higher than control group (P < 0.01). (3) The positive relationship between the level of free fDNA in maternal plasma and beta-hCG concentration in maternal serum was observed among three groups (r = 0.83, P < 0.05; r = 0.76,P < 0.01; r = 0.86,P < 0.01). Free fDNA in maternal plasma might be a candidate marker used for prenatal DS screening. However, its clinical value need to be evaluated because of positive correlation between free fDNA and beta-HCG in maternal circulation.