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2023 ACMG Annual Clinical Genetics Meeting Digital ...
Molecular findings of a placental mass in associat ...
Molecular findings of a placental mass in association with neonatal mosaic trisomy 21: teratoma versus monozygotic acardiac amorphous twin
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A case study discusses the genetic profile of a placental mass initially considered to be a placental teratoma but later determined to be consistent with an acardiac amorphous twin. The study presents evidence that previously documented placental teratomas may actually represent acardiac amorphous twins based on the similarity of short tandem repeat (STR) polymorphic loci between the mass and adjacent normal placental tissue.<br /><br />The case involves a newborn with mosaic Trisomy 21 (T21), which is most commonly caused by meiotic non-disjunction. The infant exhibited various dysmorphic features and was diagnosed with mosaic T21 after postnatal cytogenetic testing.<br /><br />The placental mass, described as a benign, non-trophoblastic mature teratoma, showed minimal differences in exome variants compared to adjacent tissue, suggesting its classification as an acardiac amorphous twin rather than a teratoma. The study proposes several explanations for the discrepancy between the mass's triplicate allele on chromosome 19 and the infant's mosaic T21.<br /><br />The study concludes that the genetic makeup of the placental mass aligns with an acardiac amorphous twin rather than a teratoma, supporting the findings of a previous study. It highlights the importance of genetic analysis in differentiating between placental masses and emphasizes that placental masses are not associated with fetal chromosomal abnormalities or adverse outcomes.<br /><br />The case also provides details about the pregnancy course, prenatal genetic testing, fetal anatomy ultrasound findings, and delivery method. The placenta itself was small for gestational age and exhibited a small nodule diagnosed as a benign, non-trophoblastic mature teratoma.<br /><br />Overall, the study contributes to the understanding of placental masses and their genetic profiles, particularly in relation to the occurrence of mosaic T21 in newborns.
Asset Subtitle
Co-Author - Madeleine Weiss, BA; Co-Author - Zahabiya H. Chithiwala, MD; Co-Author - Anthony N. Karnezis, MD, PhD; Co-Author - Jeremy R. Chien, PhD; Co-Author - Herman L. Hedriana, MD; Presenting Author - Krishna R. Singh, MD, FACMG, FACOG;
Meta Tag
Chromosomal Abnormalities
Clinical Cytogenetics
Fetal Pathology
Noninvasive prenatal screening (NIPS)
Pathology
Prenatal Diagnosis
Co-Author
Madeleine Weiss, BA
Co-Author
Zahabiya H. Chithiwala, MD
Co-Author
Anthony N. Karnezis, MD, PhD
Co-Author
Jeremy R. Chien, PhD
Co-Author
Herman L. Hedriana, MD
Presenting Author
Krishna R. Singh, MD, FACMG, FACOG
Keywords
placental mass
placental teratoma
acardiac amorphous twin
short tandem repeat
polymorphic loci
mosaic Trisomy 21
meiotic non-disjunction
exome variants
chromosome 19
fetal chromosomal abnormalities
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