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Case Reports
. 2022 Jun 29;12(7):1591.
doi: 10.3390/diagnostics12071591.

Non-Invasive Prenatal Screening: The First Report of Pentasomy X Detected by Plasma Cell-Free DNA and Karyotype Analysis

Luigia De Falco  1 , Teresa Suero  1   2 , Giovanni Savarese  1   2 , Pasquale Savarese  1   2 , Raffaella Ruggiero  1   2 , Antonella Di Carlo  1   2 , Mariasole Bruno  1   2 , Nadia Petrillo  1   2 , Monica Ianniello  1   2 , Ciro Scarpato  3 , Camilla Sarli  4   5 , Antonio Fico  1   2
Affiliations
Case Reports

Non-Invasive Prenatal Screening: The First Report of Pentasomy X Detected by Plasma Cell-Free DNA and Karyotype Analysis

Luigia De Falco et al. Diagnostics (Basel). .

Abstract

Pentasomy X is a sex chromosome anomaly caused by the presence of three extra X chromosomes in females (49,XXXXX instead of 46,XX) and is probably due to a nondisjunction during the meiosis. So far, only five cases prenatally diagnosed were described. The main features in 49,XXXXX karyotype include severe intellectual disability with delayed speech development, short stature, facial dysmorphisms, osseous and articular abnormalities, congenital heart malformations, and skeletal and limb abnormalities. Prenatal diagnosis is often difficult due to the lack of a clear echographic sign like nuchal translucency (NT), and mostly cases were postnatally described. We report the first case of a 49,XXXXX female that was detected by non-invasive prenatal screening (NIPS), quantitative fluorescence polymerase chain reaction (QF-PCR) and a fetal karyotype.

Keywords: karyotype; non-invasive prenatal screening (NIPS); prenatal screening; quantitative fluorescent-polymerase chain reaction (QF-PCR); sex chromosome anomaly.

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Figures

Figure 1
Figure 1
Cytogenetics characterization of amniotic fluid. (A) QF-PCR analysis. Informative STR markers on all autosomal chromosomes demonstrate a normal 1:1 marker ratio. The presence of AMELX and the absence of AMELY and SRY is consistent with female gender. The T1 and T3 markers are non-polymorphic (non-STR) X chromosome counting markers that may be used to determine the number of X chromosomes. The abnormal marker ratio (1:5) of the X chromosome counting markers (T1 and T3) is consistent with an abnormal female X chromosome dosage. Informative X chromosomal STR markers (X1, X3, X9) demonstrate abnormal marker ratios, and is consistent with the dosage of more than three X chromosomes. Informative pseudoautosomal STR markers (XY2 and XY3) demonstrate an abnormal (4:1) marker ratio; (B) GTG banding analysis of amniotic fluid show a 49,XXXXX karyotype.
Figure 1
Figure 1
Cytogenetics characterization of amniotic fluid. (A) QF-PCR analysis. Informative STR markers on all autosomal chromosomes demonstrate a normal 1:1 marker ratio. The presence of AMELX and the absence of AMELY and SRY is consistent with female gender. The T1 and T3 markers are non-polymorphic (non-STR) X chromosome counting markers that may be used to determine the number of X chromosomes. The abnormal marker ratio (1:5) of the X chromosome counting markers (T1 and T3) is consistent with an abnormal female X chromosome dosage. Informative X chromosomal STR markers (X1, X3, X9) demonstrate abnormal marker ratios, and is consistent with the dosage of more than three X chromosomes. Informative pseudoautosomal STR markers (XY2 and XY3) demonstrate an abnormal (4:1) marker ratio; (B) GTG banding analysis of amniotic fluid show a 49,XXXXX karyotype.
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References

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