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Chromosomal mosaicism confined to chorionic tissue.
B Schulze1, C Schlesinger, K Miller
1Abteilung Humangenetik, Medizinische Hochschule Hannover, Federal Republic of Germany.
Prenatal Diagnosis
|July 1, 1987
Summary
Fetal diagnosis revealed trisomy 3 and trisomy 15 in chorionic villus samples from two pregnancies. However, subsequent fibroblast cultures showed normal karyotypes after pregnancy termination, indicating mosaicism.
Area of Science:
- Genetics
- Prenatal Diagnosis
- Cell Biology
Background:
- First-trimester fetal diagnosis is crucial for identifying chromosomal abnormalities.
- Chorionic villus sampling (CVS) is a common prenatal diagnostic technique.
- Mosaicism, the presence of cell lines with different karyotypes, can complicate diagnosis.
Purpose of the Study:
- To investigate chromosomal abnormalities detected via chorionic villus sampling in early pregnancy.
- To determine the true fetal karyotype when initial CVS results suggest aneuploidy.
Main Methods:
- Chorionic villus samples were obtained from two healthy pregnant females during the first trimester.
- Karyotyping was performed on the chorionic villus samples.
- Fibroblast cultures were established from samples after pregnancy termination for further karyotyping.
Main Results:
- Initial karyotyping of chorionic villus samples revealed trisomy 3 (47,XX,+3) in one case and trisomy 15 (47,XX,+15) in the other.
- Subsequent karyotyping of fibroblast cultures from both cases showed a normal female karyotype (46,XX).
Conclusions:
- The findings suggest confined placental mosaicism, where chromosomal abnormalities are present in the placenta but not in the fetus.
- Discordance between CVS and fetal tissue karyotypes highlights the importance of further investigation in cases of suspected mosaicism.
- Normal fetal karyotypes in fibroblast cultures indicate that the fetus was likely unaffected by the trisomies detected in the villi.