Maternal serum screening for chromosome defects: human chorionic gonadotropin versus its free-beta subunit.
The addition of maternal serum intact hCG (MShCG) to routine maternal serum alpha-fetoprotein screening for Down's syndrome is expected to yield a detection efficiency around 60% for an amniocentesis rate approximating 5%. We compared the detection rate using intact MShCG and free-beta hCG in 480 normal pregnancies and 48 with chromosome defects (Down's syndrome 31, other chromosome defects 17). No significant difference in detection efficiency was determined. However, since the false-positive rate with free-beta hCG was almost twice that found with intact hCG, and the detection rate for other chromosome defects was more than double, the intact MShCG assay is currently preferred. Free-beta hCG earlier in gestation may, however, ultimately prove superior in maternal screening for chromosome defects.
Milunsky
A
A
Center for Human Genetics, Boston University School of Medicine, Mass. 02118.
Nebiolo
L M
LM
Bellet
D
D
D000328:Adult; D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D002869:Chromosome Aberrations; D004314:Down Syndrome / Q000175:diagnosis*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D010446:Peptide Fragments / Q000097:blood*; D011247:Pregnancy; D011296:Prenatal Diagnosis; D000509:alpha-Fetoproteins / Q000032:analysis
D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments; D000509:alpha-Fetoproteins