Proteome profiling of early gestational plasma reveals novel biomarkers of congenital heart disease

Prenatal diagnosis of congenital heart disease (CHD) relies primarily on fetal echocardiography conducted at mid-gestational age-the sensitivity of which varies among centers and practitioners. An objective method for early diagnosis is needed. Here, we conducted a case-control study recruiting 103 pregnant women with healthy offspring and 104 cases with CHD offspring, including VSD (42/104), ASD (20/104), and other CHD phenotypes. Plasma was collected during the first trimester and proteomic analysis was performed. Principal component analysis revealed considerable differences between the controls and the CHDs. Among the significantly altered proteins, 25 upregulated proteins in CHDs were enriched in amino acid metabolism, extracellular matrix receptor, and actin skeleton regulation, whereas 49 downregulated proteins were enriched in carbohydrate metabolism, cardiac muscle contraction, and cardiomyopathy. The machine learning model reached an area under the curve of 0.964 and was highly accurate in recognizing CHDs. This study provides a highly valuable proteomics resource to better recognize the cause of CHD and has developed a reliable objective method for the early recognition of CHD, facilitating early intervention and better prognosis.

Follow-up of sonographically detected soft markers for fetal aneuploidy

Sonographic soft markers of fetal Down syndrome were first reported in the 1980s. With improvements in aneuploidy screening, detection rates of 90% and higher are possible, and such screening is offered to women of all ages. The utility of sonographic detection and reporting of soft markers, particularly to women at low risk of fetal aneuploidy, is controversial. Some soft markers have no additional significance beyond an association with aneuploidy, while some potentially indicate other pathology, and therefore require sonographic follow-up or other evaluation. The definitions of soft markers vary among reported series, and any practice using such markers to adjust the risk of aneuploidy should carefully determine the most appropriate definitions as well as likelihood ratios and how to apply these in practice.

Second trimester serum predictors of congenital heart defects in pregnancies without chromosomal or neural tube defects

OBJECTIVE

To compare euploid pregnancies with congenital heart defects (CHDs) to similar pregnancies without CHDs on typically collected second trimester biomarker measurements.

METHOD

Second trimester serum levels of alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), and unconjugated estriol were compared for 306 CHD cases and 1224 no-CHD controls drawn from a sample of singleton pregnancies without chromosomal or neural tube defects (NTDs). Logistic regression models were built comparing biomarkers for cases and controls.

RESULTS

Regardless of the severity of defect, CHD cases were more likely to have unusually high AFP and/or hCG levels and/or unusually low hCG and/or uE3 levels [odds ratio (OR) 1.8-2.4, 95% confidence intervals (CIs) 1.2-4.0]. Cases with critical CHDs were more than twice as likely to have an AFP multiple of the median (MoM) ≥ the 95th percentile and/or an hCG and/uE3 MoM ≤ the 5th percentile (OR 2.1-3.9, 95% CIs 1.1-7.8).

CONCLUSION

Abnormal levels of specific second trimester maternal serum biomarkers indicated an increased risk for CHDs among this sample of low risk pregnancies. Our data suggest that future efforts aimed at improving CHD detection in low risk pregnancies may benefit from considering serum biomarkers.

Combining fetal nuchal fold thickness with second-trimester biochemistry to screen for trisomy 21

OBJECTIVE

To assess second-trimester screening for trisomy 21 by combining ultrasound nuchal fold (NF) measurement with maternal serum biochemistry.

METHODS

NF, maternal serum alpha-fetoprotein (AFP) and free beta-human chorionic gonadotropin (beta-hCG) were determined concurrently at 14-19 weeks' gestation in a study population comprising 1813 women with singleton pregnancies, including 1257 unselected women undergoing serum screening for trisomy 21 (1999-2002), and 556 high-risk pregnancies prior to amniocentesis (2003-2005), 402 of whom had positive serum screening tests. The results were expressed in multiples of the gestation-specific normal median (MoMs).

RESULTS

There were 1799 unaffected singleton pregnancies, and their NF values approximately fitted a log Gaussian distribution over a wide range. There was a weak but statistically significant correlation between log NF and log AFP (r = - 0.069, P < 0.005) and the correlation coefficient between log NF and log free beta-hCG was even smaller and not statistically significant (r = 0.038, P = 0.11). Among the seven trisomy 21 pregnancies, the median NF level was 1.53 MoM (geometric mean 1.75 MoM), a highly statistically significant increase compared with unaffected pregnancies (P < 0.0001, one-tail Wilcoxon Rank Sum Test). In pregnancies referred because of positive serum screening tests (391 unaffected, seven cases of trisomy 21, one of monosomy X and three other chromosomal anomalies) the use of NF to modify the serum screening risk would have reduced the invasive procedures in unaffected pregnancies by 46% without affecting the detection rate of trisomy 21 or other anomalies. Statistical modeling predicted that adding NF to AFP and free beta-hCG would increase detection more than would adding unconjugated estriol as well as inhibin-A, an analyte that is difficult to measure with precision.

CONCLUSIONS

The addition of NF measurement to second-trimester biochemical markers improves screening performance, and could overcome drawbacks in the implementation of inhibin-A assay in clinical practice.

The second trimester genetic sonogram

The genetic sonogram, a fetal anatomic survey targeted at identifying features associated with aneuploidy, is carried out between 15 and 20 weeks' gestation. It has evolved as an adjunctive screening tool capable of further refining the individualized risk-calculation for trisomy that is based on maternal age or serum screening markers. The significance of a range of major structural anomalies and so-called "soft-markers" for trisomy, detected both in isolation and in combination, has been widely investigated. This review serves to describe the key components of the second trimester genetic sonogram and to illustrate how these markers are integrated into risk assessment for aneuploidy.

Isolated fetal intracardiac hyperechogenic focus associated with neonatal outcome and triple test results

OBJECTIVE

To investigate the relationship between isolated intracardiac hyperechogenic focus (IHF) in the mid trimester of pregnancy with neonatal outcomes and triple test results.

MATERIALS AND METHODS

The study included low-risk pregnant women who came for routine follow-up to our antenatal clinic between years 2000 and 2005. A detailed structural survey by ultrasound (USG) of the fetal heart was performed on each fetus in the mid-trimester of pregnancy. All patients had mid-trimester triple tests performed between the 16th and 18th weeks' of pregnancy. We recruited a total of 40 pregnancies that had fetal IHF in the level II USG examination and a control group of 100 healthy pregnant women those which were followed-up during the same period. Twenty-nine fetuses (72.5%) had left, 8 (20%) had right whereas 3 (7.5%) had bilateral ventricular IHF. We compared the perinatal and neonatal outcomes and triple test results of the fetuses that had right and left IHF, and the controls.

RESULTS

Cytogenetic amniocentesis was performed to 6 (15%) women in the study and 5 (5%) in the control group and all were normal. During follow-up IHF spontaneously disappeared in 30 fetuses [right (n: 5), left (n: 23) or bilateral (n: 2)]. We did not observe any cardiac problem in the postnatal period in all newborns. Only one infant (2.5%) in the study group was admitted to neonatal intensive care unit because of prematurity. Median delivery weeks (P = 0.023), head circumference (P = 0.013), 5-min Apgar score (P = 0.021] and apnea (P = 0.042) were significantly higher in fetuses with right IHF. Compared to the controls, median delivery weeks (P = 0.038) was significantly higher in fetuses with right IHF, but head circumference (P = 0.004), 1-min (P = 0.003) and 5-min (P < 0.001) Apgar scores were lower in fetuses with left IHF. However no difference was observed in second-trimester serum human chorionic gonadotropin (HCG), alpha-fetoprotein (AFP) and estriol (E(3)) levels, in the three groups. There was no correlation between serum HCG, AFP and E(3) levels and the presence of IHF.

CONCLUSIONS

Isolated IHF in the fetal heart in the mid-trimester of pregnancy seems not associated with adverse neonatal outcome and does not correlate with triple test results.

Normal obstetric ultrasound reduces the risk of Down syndrome in fetuses of older mothers

The objective of this study is to determine whether a normal fetal morphology ultrasound scan in women older than 35 years reduces the risk of aneuploidy. We reviewed the results of amniocentesis and second trimester sonogram in all women older than 35 years from 1991 to 1995. None had prior screening. We excluded fetuses with structural anomalies. We determined the sensitivity and specificity of minor markers in detecting Down syndrome and also determined the reduction in risk of a normal sonogram. Among the 2060 women older than 35 years giving birth during the study period, 16 (0.78%) delivered an infant with Down syndrome. Of the 16 fetuses, two had no prenatal testing or ultrasound, two had invasive testing but no second trimester sonogram, five had a normal sonogram and seven had one or more sonographic markers of Down syndrome. At least 17% of women older than 35 years did not participate in prenatal testing or ultrasound. Ultrasound detected Down syndrome with a sensitivity of 59% (95% confidence interval: 45-72%), a false-positive rate of 10.6% (9.4-11.8%) and a positive predictor value of 1 in 9. The likelihood of having normal karyotype if the sonogram was normal was 0.46 (0.31-0.61). In women older than 35 years, a normal second trimester sonogram reduces the risk of Down syndrome by more than 50%. At least 17% of women older than 35 years do not participate in prenatal testing or ultrasound.

Isolated echogenic intracardiac foci in patients with low-risk triple screen results: assessing the risk of trisomy 21

OBJECTIVE

While an echogenic intracardiac focus (EIF) is associated with an increased risk of trisomy 21 (T21), the magnitude of that risk remains controversial, particularly in the setting of a low-risk triple screen (TS). The objective of this study is to define the risk of T21 in patients with a low-risk TS and an isolated EIF.

STUDY DESIGN

A retrospective analysis was performed on patients presenting prior to 22 6/7 weeks of gestation. Patients met criteria for inclusion if an EIF was noted, a TS had been drawn, the anatomic survey was complete and was determined to be normal, and karyotyping or delivery occurred at Bellevue Hospital. A high-risk TS was defined as a risk of <1:500, assuming a 2-fold increased risk in the setting of an isolated EIF. A low-risk TS was defined as a risk of >1:500. Statistical analysis was performed using chi-square, with p values of <0.05 considered significant.

RESULTS

7,318 anatomic surveys were performed. An EIF was identified in 584 patients (7.98%), of which 391 met the criteria for inclusion. Of the 391, 51% were Asian and 38% were Hispanic; 348 had a low-risk TS and 43 had a high-risk TS. Patients with an EIF and a low-risk TS had a significantly lower risk of having a T21 pregnancy compared to those with a high-risk TS and an EIF (0 vs. 2.3%; p = 0.004).

CONCLUSION

An isolated EIF with a low risk TS is not associated with an increased risk of T21.

[Role of "subtle" ultrasonographic signs during antenatal screening for trisomy 21 during the second trimester of pregnancy: meta-analysis and CPDPN protocol of the Grenoble University Hospital]

OBJECTIVE

A meta-analysis about subtle ultrasonographic signs in second trimester of pregnancy.

MATERIALS AND METHODS

196 articles dealing with the subject--from 1985 to July 2002--were studied. Data on the 11 reported signs were collected from 92 theoretically and/or statistically valid studies. Then, the studies were selected according to several criteria: isolated characteristic, defined thresholds, calculable sensitivity and specificity. After checking for homogeneity, a likelihood ratio was calculated for some of the signs.

RESULTS

This meta-analysis of the second trimester ultrasonographic signs of Down's syndrome enabled us to estimate the likelihood ratio (LHR) of six signs. At 22 weeks'gestation (WG) these signs are: pyelectasis equal to or greater than 5 mm; nuchal fold thickness equal to or greater than 6 mm; persistence of choroid plexus cysts; shortness of the femur and humerus below the tenth percentile; hyperechogenic bowe; and nasal bone length less than 2.5 mm.

CONCLUSION

These validated ultrasonographic signs are independent of nuchal translucency thickness at 12 WG and of maternal serum biochemistry. This allows to calculate a combinate risk for nuchal translucency, maternal serum biochemistry and second trimester ultrasonographic signs when they are validated.

Cost-effectiveness model for first-trimester versus second-trimester ultrasound screening for down syndrome

PURPOSE

To develop a cost-effectiveness analysis model from the perspective of Medicare reimbursement to evaluate the costs and potential risks involved in performing second-trimester genetic sonography following the first-trimester sonographic measurement of nuchal translucency and serology for Down syndrome screening.

METHODS

Three clinical screening algorithms were constructed that detailed the diagnostic evaluation of the target population by using first-trimester or second-trimester ultrasound and appropriate serologies or first-trimester and second-trimester screening in combination. The cost analysis was then created by using a computer spreadsheet program by applying Medicare reimbursement, the prevalence of Down syndrome, and reported sensitivities of first-trimester and second-trimester ultrasound and analytes for Down syndrome for each clinical algorithm. Medicare Current Procedural Terminology codes, total relative value units, and payments for first-trimester and second-trimester ultrasound, chorionic villous sampling, amniocentesis, and serum analytes were obtained from the Medicare Part B Washington 2002 Provider Disclosure Report.

RESULTS

At any given prevalence of Down syndrome, first-trimester screening is always slightly less expensive to society than the other two models for both total cost and cost to diagnose each case of Down syndrome. Even if second-trimester screening were 100% sensitive, the sensitivity of first-trimester screening would have to fall below 55% for model 2 to be cheaper than model 1. Combining both first-trimester and second-trimester screening was substantially more expensive than models 1 or 2. More iatrogenic fetal deaths occur with combined screening than with either first or second trimester screening alone.

CONCLUSIONS

Screening using first-trimester ultrasound and serologic markers to screen for Down syndrome is always slightly less expensive to society than second-trimester serologic and ultrasound screening. However, there is a significantly increased risk for iatrogenic fetal death if second-trimester genetic sonography is performed following normal first-trimester screening using currently accepted risk ratios. Patients should be counseled appropriately with this information, because an individual's circumstances will affect that person's perception of risk and subsequently affect his or her decision making.

Correlation of second-trimester sonographic and biochemical markers

OBJECTIVES

To investigate correlations between sonographic soft markers and biochemical markers (human chorionic gonadotrophin, alpha-fetoprotein, and estriol) for Down syndrome in the second trimester of pregnancy.

METHODS

A total of 2183 women with apparently normal singleton fetuses who underwent second-trimester sonography (14-22 weeks) and maternal serum biochemical testing (triple test) were identified. Seven sonographic markers were recorded: nuchal fold thickness, humerus length, femur length, renal pyelectasis, hyperechoic bowel, echogenic intracardiac focus, and choroid plexus cysts.

RESULTS

Weak negative but statistically significant correlations were observed between human chorionic gonadotropin (multiples of the median) and both femur length (multiples of the median; Spearman p = -0.073; P < .01) and humerus length (multiples of the median; Spearman p = -0.083; P < .01). No other correlations significant at the 1% level were observed between femur length (multiples of the median) or humerus length (multiples of the median) and the biochemical markers. There were no significant correlations between nuchal fold thickness and any of the 3 biochemical markers. At the 5% (P < .05) level, the median human chorionic gonadotropin level (multiples of the median) was lower when an echogenic intracardiac focus was detected. Hyperechoic bowel also tended to be associated with higher median human chorionic gonadotropin (multiples of the median) and alpha-fetoprotein (multiples of the median) levels (P < .05).

CONCLUSIONS

We found that sonographic and biochemical markers for trisomy 21 are largely independent in unaffected pregnancies. For accurate risk estimation, correlations in both affected and unaffected pregnancies need to be considered. No or minimal correlation between sonographic markers and serum screening tests indicates that they can be used as independent modifiers of the maternal age-specific risk for Down syndrome.

Levels of alpha-fetoprotein during pregnancy and early infancy in normal and disease states

Alpha-fetoprotein (AFP) was 1 of the first serum protein markers to serve in the dual capacities of tumor marker and fetal defect marker, ie, an oncofetal protein, in the clinical laboratory. Although the serum-marker capacity of AFP has long been used, less is known of the fluid compartments of this oncofetal protein during fetal and perinatal development. In this review, the biologic activities of AFP are discussed in light of its presence in the various biologic fluid compartments: fetal serum, amniotic fluid, cord blood, urine, and maternal serum. AFP concentrations within the biologic fluids are considered in the context of gestational age, sex, body weight, and anatomic location. Discussion follows concerning the relationships and roles of AFP in various developmental disorders such as hypothyroidism, folate deficiencies, autoimmune disorders, acquired immunodeficiency disorder (AIDS), congenital heart defects, cystic fibrosis, preeclampsia/hypertension, and platelet aggregation disorders. Based on its presence in so many types of birth defects, malformations, and congenital anomalies, AFP can be seen to serve as a form of molecular "duct tape" during pregnancy and postnatal development.

Genetic sonography: an option for women of advanced maternal age with negative triple-marker maternal serum screening results

OBJECTIVE

To determine whether offering genetic sonography to patients 35 years of age and older with negative maternal serum triple-marker screening results will result in an increase in the detection rate of trisomy 21.

METHODS

The detection rate of trisomy 21 was determined in women 35 years of age and older whose pregnancies were managed according to the following 3 policies: policy I, universal amniocentesis; policy II, maternal serum triple-marker screening followed by amniocentesis only in high-risk women (risk >1:190); and policy III, genetic sonography in women with negative maternal serum screening results (policy II). Policy III included the offering of genetic amniocentesis to patients with abnormal genetic sonographic findings. The rate of acceptance of genetic amniocentesis was modeled, as was the sensitivity (50%-90%) and false-positive rate (5%-25%) of genetic sonography.

RESULTS

The number of fetuses expected to have trisomy 21 was 784. For patients evaluated under policy II, 86.3% of fetuses with trisomy 21 were detected. On the basis of the detection rate for trisomy 21 of policy II, the addition of fetuses with trisomy 21 identified under policy III was significantly (P < .01) increased (93.2% to 98.6%) for genetic sonographic sensitivities ranging between 50% and 90%.

CONCLUSIONS

A policy of offering genetic sonography followed by amniocentesis to patients 35 years of age and older who originally had triple-marker maternal serum screening findings that were negative for the diagnosis of trisomy 21 results in a higher overall detection rate of trisomy 21.

Fetal karyotyping after 28 weeks of gestation for late ultrasound findings in a low risk population

OBJECTIVE

To analyze the indications and the results of invasive testing for fetal karyotyping for ultrasound abnormality in the third trimester of pregnancy, when first- and second-trimester screening tests were negative.

METHODS

Retrospective study of 171 consecutive pregnancies that underwent invasive testing after 28 weeks of gestation in 2 institutions between January 1999 and December 2001. Forty-one patients did not have any form of screening for fetal aneuploidy beforehand. One hundred and thirty of them had a normal first-trimester scan and a low risk of fetal aneuploidy by nuchal translucency and/or maternal serum screening and were included in the statistical analysis.

RESULTS

Mean maternal age, gestational age at diagnosis and at invasive testing were 30.5 years; 29.3 weeks and 32.5 weeks respectively. Amniocentesis and fetal blood sampling were performed in 97 and 33 cases respectively. The most frequent indications for invasive testing in the third trimester were major fetal malformations (51%) and intrauterine growth restriction (19%) detected on routine second- or third-trimester ultrasound examination. Ultrasound markers of aneuploidy and polyhydramnios accounted for 17 and 11% of the indications respectively. Fetal karyotype was normal in 121/130 cases. A gene mutation was found in one case. The karyotype was abnormal in nine cases, including seven cases of aneuploidy (one Turner syndrome, three trisomy 18, and three trisomy 21) and two cases of structural chromosomal abnormalities (46,XX, del 4 p16.1 and 46,XX, dup1). One hundred cases resulted in the delivery of a normal baby. Thirty cases led to termination of pregnancy or intrauterine death due to major fetal malformations (N = 25), abnormal karyotype in six of these, and severe IUGR (N = 5) with normal karyotype. Fetal US markers of aneuploidy and isolated polyhydramnios were associated with a favorable outcome in all cases.A significant increase in the risk of chromosomal anomaly was seen when two or more anomalies were found, rising from 2% with one anomaly to 21% when two or more anomalies were present.

CONCLUSION

In low risk patients, fetal karyotyping in the third trimester may be justified when the diagnosis of fetal malformation is made in the third trimester of pregnancy. Two or more anomalies increase the risk of fetal aneuploidy even with a negative-screening test in the first and second trimester of pregnancy.

Advances in prenatal screening for Down syndrome: I. general principles and second trimester testing

BACKGROUND

Down syndrome is one of the most important causes of mental retardation in the population. In the absence of prenatal screening and diagnosis, prevalence at birth in the United States would currently exceed 1:600. The purpose of prenatal screening is to identify those women at the increased risk for an affected pregnancy and to maximize the options available to these women.

TESTS AVAILABLE

Second trimester serum screening involves combining the maternal age-specific risk for an affected pregnancy with the risks associated with the concentrations of maternal serum alpha-fetoprotein (MSAFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG) (triple testing). A forth analyte, inhibin-A (INH-A), is increasingly being utilized (quadruple testing). Optimal second trimester screening requires the integration of a number of clinical variables, the most important of which is an accurate assessment of gestational age. In addition to Down syndrome, the triple and quadruple tests preferentially identify fetal trisomy 18, Turner syndrome, triploidy, trisomy 16 mosaicism, fetal death, Smith-Lemli-Opitz syndrome, and steroid sulfatase deficiency. Some programs modify the Down syndrome risks generated through maternal serum screening tests with fetal biometric data obtained by ultrasound. Other second trimester tests have shown promise, including the analysis of maternal urine and fetal cells in the maternal circulation, but none are in routine clinical use.

CONCLUSION

The second trimester triple and quadruple tests provide benchmarks for evaluating new screening protocols. The combination of fetal biometry, new test development as well as clarification of the role of co-factors that affect the concentrations of analytes in existing tests should lead to greater efficacy in second trimester screening for Down syndrome.