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Down syndrome in monochorionic twins.
1Raffles Women's Centre, Raffles Hospital, 585 North Bridge Road, #12-00, Singapore.
Singapore Medical Journal
|August 1, 2009
Summary
This case report details a rare prenatal diagnosis of Down syndrome in monochorionic twins. Early screening and ultrasound identified the condition, leading to termination.
Area of Science:
- Maternal-Fetal Medicine
- Prenatal Diagnostics
- Genetics
Background:
- Monochorionic twins share a placenta, increasing risks for complications.
- Down syndrome (Trisomy 21) is a genetic disorder typically screened for during pregnancy.
- Prenatal diagnosis of Down syndrome in monochorionic twins is infrequently documented.
Observation:
- Maternal serum screening at 15 weeks indicated a high risk (>1:50) for Down syndrome.
- Early ultrasonography confirmed a monochorionic twin pregnancy.
- Amniocentesis on one twin sac at 17 weeks confirmed Down syndrome.
Findings:
- A subsequent screening scan at 19 weeks revealed absent nasal bones in both twins.
- This suggests potential concordance of Down syndrome in both fetuses.
- The case highlights diagnostic challenges in multiple gestations.
Implications:
- Early and accurate prenatal diagnosis is crucial for informed decision-making.
- Monochorionic twin pregnancies require careful monitoring for specific genetic conditions.
- Further research is needed on the incidence and presentation of Down syndrome in monochorionic twins.
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