Size distribution of cell-free DNA in maternal plasma / 国际检验医学杂志

ABSTRACT

Objective To investigate the size distribution and change of plasma DNA in different gestational weeks between the normal and abnormal pregnancy.Methods Two methods were applied to measuring the lengths of different derived plasma DNA fragments.For the maternal derived DNA,GAPDH gene distribution of each DNA in size-fractionated fragment was assayed by real-time PCR after gel electrophoresis separation;for the fetal derived DNA,size distribution of SRY gene of fetal derived DNA was also determined by using a series of real-time PCR.Results Compared with that of matenal derived DNA,the fragment length of fetal derived DNA was mostly shorter than 300 bp.Compared with that in mid-pregnancy,plasma maternal derived DNA fragment distribution had no significant difference in late-pregnancy and in patients with high-risk of carrying a Down's child,whereas fetal derived DNA fragment was a bit longer.Conclusion The fragment length of fetal derived DNA is significantly longer than that of fetal one in maternal blood.Moreover,because of abnormal pregnancy and accompanied with the pregnancy progress,the number and physico-chemical property(fragment length,for example) of fetal derived DNA has a certain change.