title: Free beta human choriogonadotropin in Down's syndrome screening: a multicentre study of its role compared with other biochemical markers.
abstract: To ascertain the value of maternal serum free beta-human choriogonadotropin subunit measurement in Down's syndrome screening and to compare its effectiveness when screening with a variety of biochemical markers, we have evaluated maternal serum free beta-human choriogonadotropin, total human choriogonadotropin, alpha-fetoprotein and unconjugated oestriol in a large multicentre study of over 2800 unaffected cases and 90 affected cases, the largest collection of Down's cases ever reported. Of all the markers identified to date, free beta-human choriogonadotropin is the marker of choice for use in Down's syndrome screening. When used in early gestation (14-16 weeks) in combination with alpha-fetoprotein and maternal age, it will allow the detection of 77% of Down's cases. A side-by-side comparison with the performance of total human choriogonadotropin shows the superior detection efficiency of free beta-human choriogonadotropin. Unconjugated oestriol adds nothing further to the detection rate compared with the use of alpha-fetoprotein and free beta-human choriogonadotropin alone, and its use results in a 1% increase in false positive rate. We conclude that unconjugated oestriol has no value in Down's screening. The superior detection rate obtained using free beta-human choriogonadotropin is a result of superior detection of Down's cases in women under 30 years old, where the free beta-human choriogonadotropin combination detects 100% more cases than does the total human choriogonadotropin combination.
mesh_terms: D015415:Biomarkers / Q000097:blood; D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human; D003627:Data Interpretation, Statistical; D004314:Down Syndrome / Q000175:diagnosis*; D004797:Enzyme-Linked Immunosorbent Assay; D004964:Estriol / Q000097:blood; D005260:Female; D005820:Genetic Testing; D006801:Humans; D008423:Maternal Age; D010446:Peptide Fragments / Q000097:blood*; D011296:Prenatal Diagnosis; D011863:Radioimmunoassay; D012307:Risk Factors; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D010446:Peptide Fragments; D000509:alpha-Fetoproteins; D004964:Estriol