产前亲子鉴定方法研究(附23例报告)

目的对23个产前案例进行亲子鉴定。方法超声监视下行羊膜穿刺术,抽取羊水30~40ml。离心收集羊水沉渣后提取其基因组DNA,同时抽取其父母双方外周血基因组DNA。应用毛细管电泳技术和五色荧光复合扩增的方法,检测所有DNA样本的16个STR基因座基因型。结果所有羊水基因组DNA均来自独立个体,无母体DNA的污染。三联体分析显示23个案例中17例为肯定亲权关系,亲子关系概率均大于0.9999,6例确定为排除亲权关系,平均排除(位点数)指标为7.67个。二联体分析显示23个案例中17例肯定父权的平均亲子关系概率为0.9997以上,6例排除亲权关系的平均排除(位点数)指标为5个,但其中1例的排除位点只有1个。结论16个STR位点的多重荧光扩增方法在对羊水中母体DNA的污染程度进行评估的同时,可以准确、可靠的应用于产前亲子鉴定。在检测单亲鉴定案例时,若排除(位点数)指标小于2时必须补充母亲样本或增加检测的STR位点指标数,直至得出明确结论。

Methodology for prenatal paternity testing(with report of 23 cases)

Objective To perform prenatal paternity testing for 23 cases. Methods Amniotic fluid, 30-40ml in volume, was obtained by amniocentesis under ultrasonic monitoring. DNA was extracted directly from sediment of amniotic fluid. DNA was also isolated from whole blood of all parents. The capillary electrophoresis and five-color fluorescent multi-amplifying were applied to detect the genotypes of 16 short tandem repeat (STR) loci (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818, FGA and Amelogenin) in all DNA samples. Results Comparing the 16 STR sites of each fetus with those of his or her parents, there was no contamination by maternal amniotic genomic DNA. For full trio paternity cases, 17 of 23 cases showed paternity inclusion with over 0.9999 of RCP on average, while 6 cases showed paternity exclusion with 7.67 exclusion loci on average. If all cases were mother-unavailable, 17 of 23 cases showed paternity inclusion with over 0.9997 of RCP on average, while 6 cases showed paternity exclusion with 5 exclusion loci on average. But one of those cases showed only 1 exclusion locus, if the case is mother-unavailable. Conclusions 16 STRs profiling, which was carried out to evaluate the contamination by maternal amniotic genomic DNA, is accurate and reliable in amniotic fluid paternity testing. When only one or two STR exclusions have been found in mother-unavailable paternity testing, more genetic markers or maternal DNA samples must be detected as complement before making final conclusions.