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Updated: May 23, 2026
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Microsatellite DNA Genotyping and Flow Cytometry Ploidy Analyses of Formalin-fixed Paraffin-embedded Hydatidiform Molar Tissues
Published on: October 20, 2019
Monozygotic twins discordant for trisomy 13.
K Wong Ramsey1, T P Slavin, G Graham
1Department of Pediatrics, University of Hawaii John A. Burns School of Medicine, Honolulu, HI, USA. karawong@hawaii.edu
Summary
Monozygotic twins can have different karyotypes, a rare occurrence. This case highlights discordant trisomy 13 in twins, with implications for understanding genetic conditions.
Area of Science:
- Reproductive Medicine
- Human Genetics
- Developmental Biology
Background:
- Monozygotic twins typically share identical genetic material.
- Discordant karyotypes in monozygotic twins are exceptionally rare, challenging established genetic principles.
- Understanding the mechanisms behind such discordance is crucial for prenatal diagnosis and counseling.
Observation:
- A case of monozygotic twins with discordant karyotypes for trisomy 13 is presented.
- Twin A exhibited trisomy 13 (47,XY,+13) with multiple congenital anomalies, while Twin B (46,XY) appeared normal initially.
- Monochorionic-diamniotic placentation with vascular anastomoses was noted, suggesting a potential route for genetic material exchange.
Findings:
- Postnatal analysis revealed 20% trisomy 13 mosaicism in the surviving Twin B.
- Zygosity testing confirmed monozygosity both prenatally and postnatally.
- Pathological examination of the placenta confirmed monochorionic-diamniotic placentation with vascular anastomoses.
Implications:
- This case provides insights into potential mechanisms causing discordant karyotypes in monozygotic twins, such as post-zygotic chromosomal errors or placental anastomoses.
- The surviving twin requires long-term monitoring for potential complications related to trisomy 13 mosaicism and uniparental disomy.
- Further research is needed to elucidate the precise mechanisms and clinical outcomes associated with such rare genetic events in twins.
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