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[Chorionic villus sampling (CVS): level of activity and methods to resolve certain difficulties in interpretation]
C D Delozier-Blanchet1, P Extermann, M A Morris
1Institut Universitaire de Génétique Médicale, Genève.
Journal De Genetique Humaine
|January 1, 1989
Summary
Prenatal chorionic villus sampling can reveal placental abnormalities not present in the fetus, leading to false positive results. Further molecular analysis is crucial for accurate diagnosis of chromosomal anomalies.
Area of Science:
- Genetics
- Prenatal Diagnostics
Context:
- Transcervical chorionic villus biopsies are a key component of prenatal diagnostic services.
- Indications for biopsies include advanced maternal age, parental anxiety, and family history of chromosomal anomalies.
- Samples are also used for fetal sex determination and DNA analysis for genetic disorders.
Purpose:
- To evaluate the accuracy of chorionic villus sampling (CVS) in detecting cytogenetic anomalies.
- To investigate discrepancies between fetal and placental karyotypes.
- To identify potential causes of false positive and false negative results in prenatal diagnosis.
Summary:
- A study of 458 chorionic villus biopsies identified eight classical trisomies and four complex chromosomal abnormalities.
- Four cases initially diagnosed with trisomies were false positives, with normal fetal karyotypes confirmed by amniocentesis or newborn analysis.
- One case of trisomy 18 with fetal growth retardation was a false positive, with the abortus showing a normal karyotype. No false negatives were observed.
Impact:
- Highlights the potential for cytogenetic discrepancies between fetal and placental tissues.
- Suggests that some chromosomal abnormalities detected in chorionic villi may be confined to the placenta (extrafetal).
- Emphasizes the importance of molecular analyses to determine the origin and significance of aneuploidy detected via CVS.