Analysis Of Confined Placental Mosaicism

Objective：To make prenatal diagnose of the positive result,which the fetal free DNA inmaternal peripheral blood showed trisomy21-syndrome by deep sequencing.Application of amniocentesis, cordocentesis and fluorescence in situ hybridization forfetal karyotype analysis,so as to eliminate the false positive results of DNAnoninvasive prenatal testing. DNA testing on the placenta after childbirth, and infantperipheral blood karyotyping make clear whether the restriction of placentalmosaicism.Methods：The amniocentesis extracting fetal amniotic fluid, culture method and fluores-cence in situ hybridization (FISH) by cells, chromosome analysis was performed onfetal cells. Cordocentesis was applicated to conduct karyotype analysis. We can usehigh-throughput DNA technique to detect the placenta, and analysis infants karyotypeby cell culture method.Results：In the320-400band stage G banding analysis of amniotic fluid cells karyotypewas46, XN/47, XN,+21(141/5), shown as21-trisomy mosaicism karyotype. Theresults of FISH and cordocentesis was normal.Placental location and maternalfetal surface is a normal karyotype and21-trisomy mosaicism karyotype, fetalplacenta and umbilical cord tissue surface is normal karyotype,which is known asconfined placental mosaicism.The chromosome karyotype of baby peripheral bloodis normal.Conclusions:1、There are false positive results in DNA noninvasive prenatal testing;2、 DNA noninvasive positive results must be determined by amniocentesisand (or) cordocentesis;3、Amniocentesis suspected mosaicism must be diagnosed by cordocentesis andFISH etc. 4、Identified as confined placental mosaicism, the postpartum must be followedup.