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Trisomy 16 mosaicism in amniotic fluid cell cultures
U Tantravahi1, C Matsumoto, J Delach
1Department of Pathology, Women and Infants Hospital, Brown University, Providence, RI, USA.
Prenatal Diagnosis
|August 1, 1996
Summary
Trisomy 16 mosaicism, identified in placental tissue, can cause elevated maternal serum markers and fetal abnormalities. Further investigation is needed to rule out fetal trisomy 16 mosaicism.
Area of Science:
- Genetics
- Prenatal Diagnosis
Background:
- Amniocentesis revealed trisomy 16 mosaicism in a patient with elevated maternal serum alpha-fetoprotein (MSAFP) and human chorionic gonadotropin (hCG).
- Fetal ultrasound showed an atrial septal defect and clinodactyly, prompting further investigation.
Observation:
- Cytogenetic analysis of fetal tissues by fluorescence in situ hybridization (FISH) did not detect significant trisomy 16 cells.
- Trisomy 16 mosaicism was confirmed in placental tissue.
- Molecular genetic analysis excluded uniparental disomy.
Findings:
- Elevated MSAFP and hCG levels are consistent with abnormal placental function in trisomy 16 mosaicism.
- The presence of trisomy 16 mosaicism in the placenta, without clear fetal evidence, raises questions about confined placental mosaicism.
- The fetus exhibited an atrial septal defect and clinodactyly.
Implications:
- High levels of hCG and MSAFP may indicate placental dysfunction associated with trisomy 16 mosaicism.
- Serial ultrasound and fetal echocardiography are recommended for high-risk pregnancies with elevated hCG and MSAFP.
- Careful evaluation is necessary to differentiate between confined placental mosaicism and broader fetal aneuploidy.