Related Experiment Videos
Monozygotic twins with discordant karyotypes: a case report
Colm P F O'Donnell1, Mark D Pertile, Leslie J Sheffield
1Department of Neonatal Pediatrics, Royal Women's Hospital, University of Melbourne, 132 Grattan Street, Carlton, Victoria 3053, Australia. colm.odonnell@rwh.org.au
The Journal of Pediatrics
|September 3, 2004
Summary
Monozygotic twins can have different genetic makeups due to errors after conception. This case shows how a twinning event and chromosome division error led to one twin having trisomy 21 (Down syndrome), while the other was unaffected.
Area of Science:
- Reproductive biology
- Human genetics
- Developmental biology
Background:
- Monochorionic twin pregnancies share a placenta, increasing risks of discordance.
- Early embryonic development involves precise cell division and genetic distribution.
Observation:
- Chorionic villous sampling revealed a normal male karyotype in a monochorionic twin pregnancy.
- At birth, one twin was morphologically normal, while the other exhibited features of trisomy 21.
Findings:
- The study identified a rare case of monozygotic twins with discordant karyotypes for trisomy 21.
- A post-zygotic twinning event coupled with a chromosome segregation error explained the observed genetic differences and chimerism.
Implications:
- This case highlights the importance of considering post-zygotic events in diagnosing genetic abnormalities in twins.
- Understanding chromosome chimerism is crucial for accurate genetic counseling and prenatal diagnosis in discordant twin gestations.