J Genet Med.  2017 Jun;14(1):31-33. 10.5734/JGM.2017.14.1.31.

A case of maternal uniparental disomy of chromosome 20 detected by noninvasive prenatal test of 1,000 high-risk pregnancies

  • 1Department of Obstetrics and Gynecology, CHA Gangnam Medical Center, CHA University, Seoul, Korea.
  • 2Green Cross Genome, Yongin, Korea. drchoeh@gmail.com
  • 3Green Cross Laboratories, Yongin, Korea.


Chromosomal loss in trisomy (trisomy rescue) to generate a disomic fetus can cause confined placental mosaicism and/or feto/placental mosaicism. After trisomy rescue event, there is a risk of fetal uniparental disomy (UPD). Noninvasive prenatal test (NIPT) reflects the genomic constitution of the placenta, not of the fetus itself. Feto-placental discrepancy can therefore cause false-positive (trisomy) NIPT results. These discordant NIPT results can serve as important clues to find UPD associated with confined placental mosaicism. We report a case with maternal UPD of chromosome 20, detected by NIPT of 1,000 high-risk pregnancies, carried out for detecting chromosomal abnormalities in Koreans.


Uniparental disomy 20; Noninvasive prenatal test
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