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First trimester fetal karyotyping: one thousand diagnoses.
Human Genetics
|March 1, 1986
Summary
This study analyzed 1000 chorionic villi samples for fetal karyotyping, revealing an overall chromosomal abnormality incidence of 7%. Advanced maternal age significantly increased the risk of unbalanced karyotypes.
Area of Science:
- Prenatal diagnostics
- Human genetics
- Cytogenetics
Background:
- First-trimester chorionic villi sampling (CVS) is a crucial diagnostic tool.
- Cytogenetic investigations are vital for identifying fetal chromosomal abnormalities.
- Maternal age and family history are key indications for prenatal genetic testing.
Purpose of the Study:
- To evaluate the diagnostic yield of CVS for cytogenetic analysis in a large cohort.
- To determine the incidence of chromosomal abnormalities based on indications and maternal age.
- To assess the impact of gestational age at sampling on abnormality detection.
Main Methods:
- Analysis of 1000 first-trimester chorionic villi samples from two laboratories.
- Standard cytogenetic techniques for fetal karyotyping.
- Categorization of samples by indication for CVS (fetal karyotyping, maternal age, etc.).
Main Results:
- Overall incidence of chromosomal abnormalities was 7% (47 balanced, 23 unbalanced).
- Unbalanced karyotype incidence increased with maternal age (2.9% for 35-37 years, 6.6% for ≥38 years).
- Early sampling (8 weeks) showed abnormal karyotypes, with specific trisomies clustering between 8-10 weeks.
Conclusions:
- CVS is effective for first-trimester cytogenetic diagnosis.
- Maternal age is a significant risk factor for chromosomal abnormalities.
- Gestational age at sampling may influence the detection of certain abnormalities.