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Reevaluating confined placental mosaicism
Gail Stetten1, Cathleen S Escallon, Sarah T South
1Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-2501, USA. gstetten@jhmi.edu
American Journal of Medical Genetics. Part A
|November 6, 2004
Summary
Confined placental mosaicism, a rare prenatal finding, requires careful genetic counseling. While often confined to the placenta, it can rarely affect fetal development, necessitating thorough follow-up.
Area of Science:
- Genetics
- Prenatal Diagnosis
- Reproductive Medicine
Background:
- Chromosomal mosaicism detected in chorionic villus samples (CVS) presents diagnostic challenges.
- Confined placental mosaicism (CPM) is a specific form where the abnormality is limited to placental tissue.
Purpose of the Study:
- To evaluate the prognostic significance of CPM diagnosed via CVS.
- To reevaluate genetic counseling protocols for CPM cases.
- To assess the risk of CPM affecting fetal tissues.
Main Methods:
- Analysis of 38 cases of chromosomal mosaicism from 4,000 CVS samples (1998-2003).
- Confirmation of true mosaicism using amniotic fluid analysis.
- Clinical and cytogenetic follow-up of 29 CPM cases throughout pregnancy, birth, and infancy.
Main Results:
- Mosaicism was identified in 38/4,000 CVS samples.
- 5/38 cases were confirmed as true mosaicism.
- In 2/29 CPM cases, low-level fetal mosaicism was detected; 1 case showed minor phenotypic abnormalities likely due to the chromosomal abnormality.
Conclusions:
- CPM diagnosis necessitates careful genetic counseling due to the small risk of fetal involvement.
- Prenatal cytogenetic results require reevaluation considering potential placental vs. fetal mosaicism.
- Long-term follow-up is crucial for understanding the implications of CPM.