title: Maternal serum hyperglycosylated human chorionic gonadotrophin (HhCG) in the first trimester of pregnancies affected by Down syndrome, using a sialic acid-specific lectin immunoassay.
abstract: In a series of 54 cases of pregnancies complicated by Down syndrome and 224 unaffected pregnancies we examined maternal serum levels of hyperglycosylated human chorionic gonadotrophin (HhCG) in samples collected in the first trimester (11-13 weeks) using a sialic acid-specific lectin immunoassay. We compared these levels with those of other potential first trimester serum markers [free beta-hCG, pregnancy-associated plasma protein A (PAPP-A) and total hCG (ThCG)] and modeled detection rates and false-positive rates of various biochemical markers in conjunction with fetal nuchal translucency (NT) and maternal age using an maternal age standardized population. Maternal serum HhCG in cases of Down syndrome were significantly elevated (median MoM 1.97) with 24/54 (44%) of cases above the 95th centile for unaffected pregnancies. Free beta-hCG was also elevated (median MoM 2.09) with 33% of cases above the 95th centile. PAPP-A levels were reduced (median MoM 0.47) with 38% below the 5th centile. ThCG levels, whilst elevated (median MoM 1.34), had only 20% of cases above the 95th centile. Maternal serum HhCG levels were not correlated with fetal NT but showed significant correlation with ThCG and free beta-hCG and with PAPP-A in the Down syndrome group (r=0.536). Maternal serum HhCG levels in cases with Down syndrome had a significant correlation with gestational age, increasing as the gestation increased. When HhCG was combined together with fetal NT, PAPP-A and maternal age, at a 5% false-positive rate the modeled detection rate was 83%, some 6% lower than when free beta-hCG was used and some 4% better than when ThCG was used. Maternal serum HhCG is unlikely to be of additional value when screening for Down syndrome in the first trimester.
authors.affiliation: Endocrine Unit, Clinical Biochemistry Department, Harold Wood Hospital, Romford, UK. KevinSpencer1@cs.com
authors.forename: K
authors.initials: K
authors.lastname: Spencer
authors.forename: J A
authors.initials: JA
authors.lastname: Talbot
authors.forename: R A
authors.initials: RA
authors.lastname: Abushoufa
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D006063:Chorionic Gonadotropin / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000097:blood*; D005189:False Positive Reactions; D005260:Female; D005865:Gestational Age; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D037102:Lectins; D008423:Maternal Age; D019158:N-Acetylneuraminic Acid; D009333:Neck / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011296:Prenatal Diagnosis; D012680:Sensitivity and Specificity; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin; D018997:Chorionic Gonadotropin, beta Subunit, Human; D037102:Lectins; C024889:glycosylated HCG; D011266:Pregnancy-Associated Plasma Protein-A; D019158:N-Acetylneuraminic Acid