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Monosomy X rescue explains discordant NIPT results and leads to uniparental isodisomy
Author(s) -
Rudd M. Katharine,
Schleede Justin B.,
Williams Sabrina R.,
Lee Kristy,
Laffin Jennifer,
Pasion Romela,
Papenhausen Peter R.
Publication year - 2018
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.5349
Subject(s) - monosomy , amniocentesis , uniparental disomy , trisomy , aneuploidy , prenatal diagnosis , amniotic fluid , medicine , genetics , obstetrics , pregnancy , gynecology , biology , chromosome , fetus , karyotype , gene
Noninvasive prenatal testing accurately detects trisomy for chromosomes 13, 21, and 18, but has a significantly lower positive predictive value for monosomy X. Discordant monosomy X results are often assumed to be due to maternal mosaicism, usually without maternal follow‐up. We describe a case of monosomy X‐positive noninvasive prenatal testing that was discordant with the 46,XX results from amniocentesis and postnatal testing. This monosomy X pregnancy doubled the single X chromosome, leading to 45,X/46,XX mosaicism in the placenta and uniparental isodisomy X in the amniotic fluid. Thus, at least some discordant monosomy X results are due to true mosaicism in the pregnancy, which has important implications for clinical outcome and patient counseling.