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Down syndrome at birth not detected by first-trimester chorionic villus sampling
I Bartels1, I Hansmann, U Holland
1Institut für Humangenetik, Universität Göttingen, Federal Republic of Germany.
American Journal of Medical Genetics
|December 1, 1989
Summary
A chorionic villus sampling (CVS) test in early pregnancy incorrectly ruled out Down syndrome. The baby was later diagnosed with Down syndrome, highlighting potential diagnostic inaccuracies in prenatal screening.
Area of Science:
- Medical Genetics
- Prenatal Diagnostics
- Human Chromosome Abnormalities
Background:
- First-trimester prenatal diagnosis aims to detect fetal chromosomal abnormalities.
- Chorionic villus sampling (CVS) is a common invasive diagnostic procedure.
- False-negative results in prenatal testing can lead to significant clinical and ethical challenges.
Purpose of the Study:
- To report a rare case of a false-negative first-trimester diagnosis of Down syndrome using chorionic villus sampling.
- To investigate the discrepancy between prenatal diagnostic results and postnatal confirmation of trisomy 21.
Main Methods:
- Chorionic villus sampling performed at 12 weeks of gestation.
- Karyotyping of cultured chorionic villi.
- Postnatal cytogenetic analysis of cultured lymphocytes from the newborn.
Main Results:
- Chromosome analysis of chorionic villi revealed a normal male karyotype (46, XY).
- The newborn exhibited clinical features consistent with Down syndrome.
- Lymphocyte analysis from the newborn showed trisomy 21 in 99% of metaphases (47, XY, +21).
Conclusions:
- This case highlights the possibility of false-negative results in chorionic villus sampling for Down syndrome.
- Discordance between CVS and postnatal karyotyping suggests potential issues like confined placental mosaicism or technical limitations.
- Careful consideration and follow-up are crucial when prenatal diagnostic results do not align with clinical presentation.