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Monozygotic twins discordant for trisomy 18.
Summary
Prenatal diagnosis for dichorionic twins requires sampling both amniotic sacs, especially when one twin shows structural abnormalities. This case highlights discordant trisomy 18, with one twin affected and the other developing normally.
Area of Science:
- Genetics
- Prenatal Diagnosis
- Twin Studies
Background:
- Monochorionic-diamniotic twin pregnancies present unique diagnostic challenges.
- Discordance for chromosomal abnormalities like trisomy 18 requires careful prenatal assessment.
Observation:
- Ultrasound at 20 weeks revealed structural anomalies in one twin.
- Amniotic fluid sampling from both sacs was performed for karyotyping.
Findings:
- Karyotyping confirmed trisomy 18 in the affected twin and a normal karyotype in the other.
- Postnatal analysis revealed low-grade trisomy 18 mosaicism in the surviving twin, who exhibited normal development.
Implications:
- Sampling both amniotic sacs is crucial for accurate prenatal diagnosis in monochorionic twins.
- Early identification of discordant genetic conditions allows for informed clinical management and counseling.
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