[Application of fetal DNA in maternal plasma for non-invasive prenatal diagnosis of fetal sex].

To investigate the feasibility and possibility of application of fetal DNA from maternal plasma for noninvasive prenatal diagnosis of fetal sex, plasma DNAs in blood samples of 73 pregnant women at the gestational period of 26 to 41 weeks were extracted by column separation and nested polymerase chain reaction were employed to amplify the SRY gene. A comparison was made between the amplification results and the real sex of the fetus after their delivery. The concordance rate of SRY gene amplification results of plasma free DNA with real fetal sex was 91.78% (67/73), the sensitivity rate was 97.37% (37/38), and the specific rate was 85.71% (30/35). The cell-free fetal DNA in maternal blood can be one of the valuable material sources for noninvasive prenatal diagnosis and the method of nested PCR could be useful for fetal sex determination. The specific rate of the test was 91.78%. It is of significance to prevent sex-linked inheritant diseases.