Human chorionic gonadotrophin (hCG) has been used as a serum biochemical marker of Down's syndrome (DS) pregnancies, and recent studies have reported an increase in a hyperglycosylated form of the protein associated with DS. In the present study, the activity of the combined soluble serum sialyltransferase (ST) enzymes was examined as a potential marker for the hyperglycosylated form of hCG. There were no changes in total ST activity during the course of the pregnancy in normal mothers and there was no difference in enzyme activity in the DS pregnancies when compared with controls. These results suggest that, although there may be an alteration in the activities of one or more of the glycosyltransferase enzymes in the placenta resulting in an alteration in hCG glycosylation, this is not reflected in the serum soluble enzyme activity.
References
1.
KatzmanR, SaitohT.Advances in Alzheimer's disease. FASEB J1991; 5: 278–86
2.
OliverC, HollandAJ. Down's syndrome and Alzheimer's disease — a review. Psychol Med1986; 16: 307–22
3.
WaldNJ, KennardA, DensemJW, CuckleHS, ChardT, ButlerL.Antenatal maternal serum screening for Down's syndrome: results of demonstration project. BMJ1992; 305: 391–4
4.
CuckleHS, WaldNJ, BarkaiG, FuhrmannW, AltandK, BrambatiB, First trimester biochemical screening for Down syndrome. Lancet1988; ii: 851–2
5.
CuckleHS, HoldingS, JonesR, GroomeNP, WallaceEM. Combining inhibin A with existing second-trimester markers in maternal serum screening for Down's syndrome. Prenat Diagn1996; 16: 1095–100
6.
GrotjanHRJr, ColeLA. Human chorionic gonadotropin micro-heterogeneity. In: GrotjanHRJr, ColeLA, eds. Microheterogeneity of Glycoprotein Hormones. Boca Raton: CRC Press, 1989: 219–37
7.
BirkenS.Chemistry of human choriogonadotropin. Ann Endocrinol (Paris)1984; 45: 297–305
8.
PetrocikE, WassmanER, KellyJC. Prenatal screening for Down syndrome with maternal serum human chorionic gonadotropin levels. Am J Obstet Gynecol1989; 161: 1168–73
9.
SpencerK, CoombesEJ, MallardAS, MilfordWA. Free beta human choriogonadotropin in Down's syndrome screening: A multicentre study of its role compared with other biochemical markers. Ann Clin Biochem1992; 29: 506–18
10.
ColeLA, OmraniA, CermikD, MahoneyRO. Hyperglycosylated hCG: a potential alternative to hCG in Down syndrome screening. Prenat Diagn1998; 18: 926–33
11.
ColeLA, CermikD, Bahado-SinghR.Oligosaccharide variants of hCG-related molecules: potential screening markers for Down syndrome. Prenat Diagn1997; 17: 1187–90
12.
BreenKC, CoughlanCM, HayesFD. The role of glycoproteins in neural development, function and disease. Mol Neurobiol1998; 16: 163–220
13.
Harduin-LepersA, RecchiMA, DelannoyP.1994: The year of the sialyltransferases. Glycobiology1995; 5: 741–58
14.
MaguireTM, GillianAM, O'MahonyD, CoughlanCM, DennihanA, BreenKC. A decrease in serum sialyltransferase levels in Alzheimer's disease. Neurobiol Aging1994; 15: 99–102
15.
LowryGH, RosenbroughNL, FarrAL, RandallRJ. Protein measurement with the folin reagent. J Biol Chem1951; 193: 265–75
16.
BreenKC, ReganCM. Synaptosomal sialyltransferase glycosylates surface proteins that are inaccessible to the actions of membrane-bound sialidase. J Neurochem1986; 47: 1176–80
17.
MaguireTM, O'MahonyD, GillianAM, DennihanA, BreenKC. The serum expression of sialoglycoproteins and sialyltransferase in Alzheimer's disease: evidence for altered expression of individual isoforms. Neurodegeneration1994; 3: 129–33
18.
MaguireTM, CoughlanCM, SecklJR, BreenKC. The effect of corticosteroids on serum sialyltransferase enzyme activities in the rat. Biochim Biophys Acta1998; 1379: 23–8
19.
CoughlanCM, SecklJR, FoxDJ, UnsworthR, BreenKC. Tissue-specific regulation of sialyltransferase activities in the rat by corticosteroids in vivo. Glycobiology1996; 6: 15–22
20.
DairakuK, MiyagiT, WakuiA, TsuikiS.Increase in serum sialyltransferase in tumor-bearing rats: the origin and nature of the increased enzyme. Gann1983; 74: 656–62
21.
MaguireTM, BreenKC. A decrease in neural sialyltransferase activity in Alzheimer's disease. Dementia1995; 6: 185–90
22.
McFarlaneI, GeorgopoulouN, CoughlanCM, GillinAM, BreenKC. The subcellular distribution and subsequent processing of the amyloid β precursor protein is influenced by its glycosylation state. Neuroscience1999; 90: 15–25
23.
ColeLA, ShahabiS, OzVA, RinneKM, OmraniA, Bahado-SinghRO, Urinary screening tests for fetal Down syndrome: ii. Hyperglycosylated hCG. Prenat Diagn1999; 19: 351–9
KraussT, KuhnW, LakomaC, AugustinHG. Circulating endothelial adhesion molecules as diagnostic markers for the early identification of pregnant women at risk for development of preeclampsia. Am J Obstet Gynecol1997; 177: 443–9
