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Human chorionic gonadotrophin and trisomy 18.
1Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel.
American Journal of Medical Genetics
|October 1, 1991
Summary
Extremely low maternal serum human chorionic gonadotropin (hCG) levels may indicate a higher risk for trisomy 18 fetuses. This finding is significant even when the estimated risk for Down syndrome appears low.
Area of Science:
- Prenatal diagnostics
- Maternal serum screening
- Fetal aneuploidy
Background:
- Maternal serum screening using alpha-fetoprotein (AFP), estriol (E3), and human chorionic gonadotropin (hCG) is standard for estimating fetal Down syndrome (DS) risk.
- Extremely low hCG levels have historically been considered clinically insignificant in prenatal screening.
Observation:
- Two cases of fetuses with trisomy 18 were identified.
- Antenatal screening in these cases revealed exceptionally low maternal serum hCG levels (0.05 and 0.15 multiples of the median).
Findings:
- Extremely low maternal serum hCG levels can be associated with trisomy 18.
- This association may be present even when the calculated risk for Down syndrome is low.
Implications:
- Clinicians should consider trisomy 18 in the differential diagnosis for pregnancies with very low hCG levels.
- Further investigation may be warranted in cases with unexpectedly low hCG, regardless of DS risk assessment.
- This highlights the potential clinical significance of low hCG in prenatal screening for chromosomal abnormalities.