- G Barkai: Institute of Human Genetics, Sheba Medical Center, Tel Hashomer, Israel.
Estimation of maternal serum beta-hCG is used in conjunction with alpha-fetoprotein (AFP) and estriol (E3) for estimating the risk of Down syndrome (DS) affected fetuses. However, low hCG levels have not been regarded as having clinical significance. We report on 2 patients with trisomy 18 fetuses in whom antenatal screening showed extremely low hCG levels (0.05 and 0.15 MOM). Low hCG levels might indicate increased risk for trisomy 18 despite low estimated risk for DS.