Placental mosaicism for Trisomy 13: a challenge in providing the cell-free fetal DNA testing.
OBJECTIVE
We investigated the disagreement between the positive cell-free fetal DNA test for trisomy 13 and the standard cytogenetic diagnosis of one case.


METHODS
Cell-free fetal DNA testing was performed by massively parallel sequencing. We used conventional cytogenetic analysis to confirm the commercial cell-free fetal DNA testing. Additionally, postnatal fluorescent in situ hybridization (FISH) testing was performed on placental tissues.


RESULTS
The cell-free fetal DNA testing result was positive for trisomy 13. G-banded analysis of amniotic fluid was normal, 46, XY. FISH testing of tissues from four quadrants of the placenta demonstrated mosaicism for trisomy 13.


CONCLUSIONS
A positive cell-free fetal DNA testing result may not be representative of the fetal karyotype because of placental mosaicism. Cytogenetic analysis should be performed when abnormal cell-free fetal DNA test results are obtained.
Center for Prenatal Diagnosis and Reproductive Medicine, The First Hospital of Jilin University, Changchun, Jilin, 130021, China.
Xiang-Yin
XY
Liu
Hong-Guo
HG
Zhang
Rui-Xue
RX
Wang
Shuang
S
Chen
Xiao-Wei
XW
Yu
Rui-Zhi
RZ
Liu
D000328:Adult; D000653:Amniotic Fluid; D000782:Aneuploidy; D025063:Chromosome Disorders / Q000235:genetics*; D002882:Chromosomes, Human, Pair 13 / Q000235:genetics; D020732:Cytogenetic Analysis / Q000379:methods; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods; D006801:Humans; D059785:Karyotype; D009030:Mosaicism; D010920:Placenta; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D014314:Trisomy / Q000235:genetics*; D000073839:Trisomy 13 Syndrome