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Query: UMLS:C0013080 (Down syndrome)
 14,180 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intrauterine fetal death occurred in four women who were 'screen-positive' in a screening programme for neural tube defects (NTDs) and Down syndrome (DS). These women had very high levels of maternal serum alpha-fetoprotein (MSAFP) and maternal serum human chorionic gonadotropin (MShCG). Therefore, we evaluated all 'screen-positive' women in whom both of these markers were greater than or equal to 2.0 multiples of the median. The cases fulfilling these criteria totalled 11, and only one of them had no complications. High concentrations of both MSAFP and MShCG in a number of these cases might have been caused by an increased placental volume, which, in turn, might have been induced by decreased perfusion of the placenta. We conclude that screening programmes wrongly determine a high risk of fetal NTD or DS if the concentrations of both these parameters are very high. Invasive diagnostic procedures should be avoided in these cases, particularly in view of the increased risk of an adverse pregnancy outcome.
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PMID:Increased maternal serum alpha-fetoprotein and human chorionic gonadotropin in compromised pregnancies other than for neural tube defects or Down syndrome. 931 37

Two prenatal centres in New England, routinely using a screening protocol for fetal Down syndrome that included maternal serum alpha-fetoprotein (AFP), unconjugated oestriol (uE3), and human chorionic gonadotropin (hCG) measurements in combination with maternal age, adopted a separate screening protocol for trisomy 18. That protocol identified a pregnancy as being at high risk when AFP, uE3, and hCG measurements all fell at or below specified cut-offs (0.75, 0.60, and 0.55 multiples of the median, respectively), regardless of maternal age. Among the first 19,491 women screened, 98 (0.5 per cent) were found to have values which placed them in the high-risk category. Four of these women were subsequently found not to be pregnant. In two others, samples from non-pregnant individuals were found to have been incorrectly submitted for analysis in place of the samples from the pregnant women. All of the remaining 92 women were counselled and offered amniocentesis and fetal karyotyping. Eighty-eight (96 per cent) accepted. Karyotypes or birth outcomes were available on all 92 pregnancies. Six cases of trisomy 18 and one case of Turner syndrome were identified by karyotype. One case of trisomy 18 was identified for every 14 unaffected pregnancies offered amniocentesis. In the present prospective study, an estimated 85 per cent of the cases of trisomy 18 were identified. However, given the small number of cases (six), the 95 per cent confidence interval for the detection rate is broad (40-95 per cent).
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PMID:Prospective intervention trial of a screening protocol to identify fetal trisomy 18 using maternal serum alpha-fetoprotein, unconjugated oestriol, and human chorionic gonadotropin. 128 34

Pregnancy and trophoblastic disease testing laboratories measure human chorionic gonadotropin (hCG; human choriogonadotropin) free beta-subunit to screen for Down syndrome and to diagnose persistent trophoblastic disease (invasive mole and choriocarcinoma). The results from various laboratories, however, vary widely for similar groups of patients. Average concentrations of free beta-subunit reported for persistent trophoblastic disease, for instance, range from 2.6% to 37% of total hCG. On hCG and its free beta-subunit, peptide bonds can be missing between beta-subunit residues 44 and 45 or between residues 47 and 48 (nicked molecules). To explore the possibility that the disparity in the reported concentrations of free beta-subunit was due to differences in recognition of nicked molecules by different antibodies, we generated 0% and 100% nicked beta-subunit standards and investigated their recognition in three separate immunoassays of free beta-subunit. The immunoassay with antibody 1E5 did not recognize nicked beta-subunit (4% cross-reactivity with nicked beta-subunit) and thus detected only intact beta-subunit. The immunoassay with antibody FBT11 gave similar results with nicked and nonnicked thus standards (96% cross-reactivity with nicked beta-subunit), as did the assay with antibody B204 (73% cross-reactivity with nicked beta-subunit). These two immunoassays thus measured total (nicked + nonnicked) beta-subunit. We used the three immunoassays to examine sera from normal pregnancy, Down syndrome pregnancy, hydatidiform mole, and persistent trophoblastic disease, all of which contain nicked and nonnicked beta-subunit molecules. The results obtained resembled the studies with nicked beta-subunit standards. The results from the FBT11 and B204 assays (total beta-subunit) were highest, results from the 1E5 assay (intact molecules only) being as much as 10 times lower. We conclude that nicks in beta-subunit and the extent of recognition of nicked molecules by different antibodies affect the concentrations reported for free beta-subunit.
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PMID:Polypeptide nicks cause erroneous results in assays of human chorionic gonadotropin free beta-subunit. 137 Jul 71

Amniotic fluid from 135 pregnancies was assayed for human chorionic gonadotropin (hCG) and its free alpha (ahCG) and free beta (bhCG) subunits. Forty-six chromosomally abnormal pregnancies between 14 and 20 weeks' gestation were matched with 89 chromosomally normal samples. Compared with controls, trisomy 21 pregnancies exhibited significantly elevated levels of all three peptides, whereas trisomy 18 gestations gave rise only to significant elevation of ahCG. Female fetuses in both the trisomy 21 and trisomy 18 pregnancies provided significantly elevated levels of hCG and bhCG compared to their male counterparts. On converting the values to multiples of the median, it was determined that 6 of 7 trisomy 18 samples had abnormally elevated alpha/beta ratios, as did 6 of 21 Down's syndrome pregnancies. Further, 11 of 21 trisomy 21 gestations had abnormal amniotic fluid hCG levels. Using only ahCG, bhCG and their ratio, a 61 per cent sensitivity was found for these trisomies, with a 96 per cent specificity.
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PMID:Amniotic fluid levels of human chorionic gonadotropin and its alpha and beta subunits in second-trimester chromosomally abnormal pregnancies. 137 34

Antenatal serum screening for Down's syndrome is now becoming established in many centers throughout the world. The screening method is based on the measurement of alpha-fetoprotein, unconjugated estriol, and human chorionic gonadotropin between 15 and 22 weeks of pregnancy. These measurements, used in conjunction with a woman's age, provide risk estimates of having a pregnancy with Down's syndrome for every woman screened. By identifying the 5% of women with highest risk and offering them an amniocentesis, about 60% of Down's syndrome pregnancies can be identified. If an ultrasound scan examination is used routinely to estimate gestational age, the detection rate can be increased by 5% to 10%. Recent information on the distribution of the three serum markers in twin pregnancies and pregnancies with insulin-dependent diabetes mellitus now means that screening can be carried out in such pregnancies. Various other serum markers of Down's syndrome have been reported, but at present they do not have a place in routine antenatal screening for Down's syndrome. The role of amniotic fluid acetylcholinesterase measurement, alone and in combination with amniotic fluid alpha-fetoprotein measurement, in the antenatal diagnosis of open neural tube defects has recently been clarified. The best policy is to perform an amniotic fluid alpha-fetoprotein measurement as the primary test and an acetylcholinesterase determination for those women who have an amniotic fluid alpha-fetoprotein measurement of two times the normal median or greater. The acetylcholinesterase can be measured either by the standard method (gel electrophoresis) or by a new quantitative monoclonal antibody method.
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PMID:Prenatal biochemical screening for Down's syndrome and neural tube defects. 137 63

CA-125, alpha-fetoprotein (AFP), and human chorionic gonadotropin (HCG) were determined in maternal serum in the first trimester from 14 women with a Down's syndrome fetus and 61 women with a healthy fetus. In the second trimester, 15 and 60 serum samples were determined from women with a Down's syndrome and a healthy fetus respectively. In both trimesters, maternal serum CA-125 was found to be elevated in Down's syndrome pregnancies compared with controls. Using discrimination functions, our preliminary results indicate that CA-125 is a better marker than AFP and HCG respectively for a Down's syndrome fetus in the first trimester and improves the detection rate in the second trimester.
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PMID:CA-125 as a maternal serum marker for Down's syndrome in the first and second trimesters. 137 79

A prenatal screening programme for Down's syndrome potentially detecting 76 per cent of affected pregnancies in the South Australian general population at an amniocentesis rate of 3.9 per cent was designed following analysis of mid-trimester serum samples from 57 women who carried an affected fetus. This equates to one affected pregnancy being detected for 41 chromosomal analyses performed. For the experimental series, 75.4 per cent of affected pregnancies were detected, while 4.1 per cent of control specimens produced estimated risk odds consistent with further action. A maternal risk odds of birth of a Down's syndrome fetus of 1:420 was taken as the decision value, which is the prevalence of Down's syndrome births to 35-year-old mothers in South Australia. This screening performance was achieved by investigating combinations of serum analytes not previously reported and by refining the calculation of maternal risk odds to include selective weighting of indicator analytes. Combination of the measurements of free alpha-subunits and beta-subunits of chorionic gonadotrophin, alpha-fetoprotein, unconjugated oestriol, and placental lactogen was found to be most effective in indicating Down's syndrome fetuses. In all combinations of analytes tested, replacing the measurements of free alpha-subunits and free beta-subunits of chorionic gonadotrophin with the measurement of intact chorionic gonadotropin produced a less effective screen.
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PMID:Improved performance in a prenatal screening programme for Down's syndrome incorporating serum-free hCG subunit analyses. 137 88

I review the utility of several common prenatal laboratory tests. Infant mortality is higher in the United States than in many other industrialized nations; better access to early prenatal care may help reduce this mortality rate. Several common laboratory tests can significantly contribute to prenatal care. Early measurement of maternal serum human chorionic gonadotropin can permit estimation of the date of conception. Use of maternal serum alpha-fetoprotein in the second trimester provides the clinician with risk estimates for neural tube defects and Down syndrome. Adding human chorionic gonadotropin and possibly unconjugated estriol to this screen can increase the number of Down syndrome cases identified without increasing the proportion of abnormal results. Amniotic fluid fetal lung maturity tests can assist with the management of delivery.
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PMID:Evaluating health and maturation of the unborn: the role of the clinical laboratory. 138 62

Introduction of maternal serum markers for prenatal screening of Down's syndrome leads to a redefinition of the criteria used for identifying at risk women (i.e. in France, mainly based on maternal age of 38 and over). Effectiveness and costs of prenatal screening of Down's syndrome using such maternal serum markers will vary depending on the biological cut-off values defined, at each maternal age, to identify the population of pregnant women that will be sent to amniocentesis. On the basis of the first French prospective study of the use of human chorionic gonadotropin (hCG) measurement in maternal serum as a predictor of an increased risk of Down's syndrome, this paper shows that a screening policy combining maternal age with hCG measurement is more cost-effective than screening on the basis of maternal age alone. However, final decisions about hCG cut-off values should take into account the complex ethical dilemmas involved, especially the potential consequences of "false positives" and "false negatives", of this marker.
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PMID:[Cost effectiveness analysis of prenatal screening of trisomy 21 by maternal serum markers (hCG)]. 149 Nov 37

The main indications for cytogenetic prenatal diagnosis have been based on pregnancies with an increased risk of chromosomal anomaly. Advanced maternal age has been the most important criterion and presently 60% of women of 38 yr and over undergo prenatal diagnosis. Fetal malformations detected by ultrasound resulted in the selection of a group in which approximately 10% chromosomal anomalies were detected. An effort has been made to describe sonographic signs indicative of Down's syndrome. Maternal serum biochemical markers constitute another approach for screening. Human chorionic gonadotropin is the most discriminant test. Combining maternal and hCG cut-off levels, it is possible to detect approximately 70% of trisomy 21% in women aged between 30-38 yr.
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PMID:[Strategies for selection of pregnancies with increased risk of fetal trisomy 21]. 166 86


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