[Detection of fetal short tandem repeat loci in maternal plasma as gender-independent fetal DNA marker].

The aim of this study was to investigate the feasibility of using fetal short tandem repeat (STR) loci in maternal plasma as gender-independent fetal DNA marker. DNA from maternal plasma sample was extracted using QIAamp DNA Kit. AmpF1 STR profiler box was used to amplify 9 different polymorphic short tandem repeat (STR) loci (D3S1358, VWA, FGA, D5S818, D13S317, D7S820, D8S1179, D21S11, D18S51), the multiplex fluorescent PCR was used to amplify the STR alleles of fetal DNA in 36 pregnant plasma samples of pregnant women at different pregnancy. Their husbands' DNA isolated from whole blood samples were amplified at the same time. The PCR products were electrophoresis by ABI Prism 377 sequencer, the results of electrophoresis were analysed by Genscan. The presence of fetal DNA in maternal plasma by Paternally inherited fetal alleles were detected. The results showed that paternally inherited fetal alleles were detected in 4 cases in early pregnancy (4/6), 19 cases in middle pregnancy (19/20) and 9 cases in late pregnancy (9/10) respectively, the paternally inherited fetal alleles in 4 of 36 cases could not be detected. It is concluded that fluorescent multiplex PCR can be used for amplification of male and female fetal STRs in maternal plasma to obtain genetic information, which may have implication for non-invasive prenatal diagnosis of certain hereditary diseases independent of the fetal sex.