Discordant results between fetal karyotyping and non-invasive prenatal testing by maternal plasma sequencing in a case of uniparental disomy 21 due to trisomic rescue

ABSTRACT Uniparental disomy (UPD) is an uncommon chromosome condition, but UPD involving chromosome 21 is rarely reported. We reported here a case who had first trimester screening test for Down syndrome, chorionic villus sampling for fetal karyotyping, quantitative fluorescence polymerase chain rea...

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Bibliographic Details
Published in:Prenatal diagnosis 2013-06, Vol.33 (6), p.598-601
Main Authors: Pan, Min, Li, Fa Tao, Li, Yan, Jiang, Fu Man, Li, Dong Zhi, Lau, Tze Kin, Liao, Can
Format: Article
Language:English
Subjects:
Adult
Chromosomes, Human, Pair 21 - genetics
Dosage Compensation, Genetic - physiology
Female
Humans
Karyotyping - methods
Mosaicism
Pregnancy - blood
Prenatal Diagnosis - methods
Sequence Analysis, DNA - methods
Trisomy - diagnosis
Trisomy - genetics
Uniparental Disomy - diagnosis
Uniparental Disomy - genetics
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Summary:ABSTRACT Uniparental disomy (UPD) is an uncommon chromosome condition, but UPD involving chromosome 21 is rarely reported. We reported here a case who had first trimester screening test for Down syndrome, chorionic villus sampling for fetal karyotyping, quantitative fluorescence polymerase chain reaction (QF‐PCR), as well as non‐invasive prenatal testing (NIPT) by maternal plasma sequencing. There were discordant results between fetal karyotyping and NIPT due to UPD 21combined with confined placental mosaicism of trisomy 21. This demonstrated that it is possible to detect placental mosaicism by NIPT, but further studies are required to confirm its sensitivity. Therefore, all positive NIPT results must be confirmed by conventional invasive test and karyotyping. QF‐PCR has the additional benefit in diagnosing UPD. © 2013 John Wiley & Sons, Ltd. What's already known about this topic? The non‐invasive prenatal testing (NIPT) by maternal plasma sequencing has been proven to be a safe and highly efficient screening method for fetal aneuploidy. Some studies suggested that these cell‐free DNAs are from the placenta. Therefore, an abnormal NIPT result could be due to confined placental mosaicism. What does this study add? We reported here a case of UPD with confined placental mosaicism, which resulted in discordant results between fetal karyotyping and NIPT.
ISSN:0197-3851
1097-0223
DOI:10.1002/pd.4069