Elizabeth Winsor

Proteomics Analysis of Human Amniotic Fluid

Amniotic fluid is a dynamic and complex mixture that reflects the physiological status of the developing fetus. In this study, the human amniotic fluid (AF) proteome of a 16–18-week normal pregnancy was profiled and analyzed to investigate the composition and functions of this fluid. Due to the complexity of AF, we utilized three different fractionation strategies to provide greater coverage. Two types of two-dimensional LC/MS/MS as well as an LC-SDS-PAGE-LC-MS/MS platform were used. A total of 16 AF samples between gestational ages of 16 and 18 weeks from women carrying chromosomally normal fetuses were analyzed by one of the three fractionation methods followed by a common reverse phase LC-MS/MS step. Mascot and The Global Proteome Machine engines were used to search the International Protein Index human database for peptide sequence identification. The list of proteins was generated by combining the results of both engines through the PeptideProphet of Scaffold software. All identified proteins were combined to generate the AF proteome comprising 1,026 unique gene matches or 842 non-redundant proteins. This list includes most of the currently used biomarkers for pregnancy-associated pathologic conditions such as preterm delivery, intra-amniotic infection, and chromosomal anomalies of the fetus. The subcellular localization, tissue expression, functions, and networks of the AF proteome were analyzed by various bioinformatic tools. These data will contribute to the better understanding of amniotic fluid function and to the discovery of novel biomarkers for prenatal diagnosis of fetal abnormalities.

Prenatally diagnosed neural tube defects: ultrasound, chromosome, and autopsy or postnatal findings in 212 cases.

From January 1990 until December 1996, 212 cases of neural tube defect (NTD) were seen through the Prenatal Diagnosis Program of the University of Toronto. Of the 212 cases, 200 were karyotyped successfully and of these, 13 (6.5%) had chromosome abnormalities. When classified according to the site of the NTD, 2.3% (2/88) of anencephalics, 7.1% (1/14) of encephaloceles, and 10.2% (10/98) of meningomyeloceles had abnormal karyotypes. The absence of associated ultrasound abnormalities was not necessarily predictive of a chromosomally normal fetus; 4/167 (2.4%) of fetuses with isolated NTDs had chromosome abnormalities. Conversely, 24/33 (72%) of fetuses with additional findings on ultrasound had normal chromosomes. The diagnosis of a chromosome abnormality associated with NTD has important implications for recurrence risk and prenatal diagnosis, not only for the parents but potentially for other relatives. Based on our finding that 6.5% of prenatally detected NTDs are associated with chromosome abnormalities, we recommend karyotyping of all fetuses and/or newborns with NTD.

Prenatal ultrasound findings of lissencephaly associated with Miller–Dieker syndrome and comparison with pre‐ and postnatal magnetic resonance imaging

To report on the prenatal ultrasound findings in fetuses with lissencephaly associated with Miller–Dieker syndrome (MDS) and to compare these findings with those of magnetic resonance imaging (MRI).

MATERNAL CELL CONTAMINATION IN UNCULTURED AMNIOTIC FLUID

The presence of maternal cells in uncultured amniotic fluid may result in error in the interpretation of prenatal tests such as direct DNA analysis and rapid aneuploidy detection by fluorescence in situ hybridization (FISH). Using simultaneous dual colour X and Y FISH, we assessed maternal cell contamination in uncultured amniotic fluids from 500 women carrying male fetuses. The presence of maternal cells was correlated with the amount of blood present in the amniotic fluid as defined by visual examination of the cell pellet after centrifugation. The overall rate of maternal cell contamination in uncultured amniotic fluid as identified using X and Y‐specific probes was 21·4 per cent, compared with 0·2 per cent in cultured fluid. Sixteen per cent of slightly bloody and 55 per cent of moderately bloody uncultured fluids had at least 20 per cent maternal cells and were classified as uninformative according to our protocol for rapid aneuploidy detection. Maternal and fetal cells could not be distinguished based on morphological characteristics alone.

Extracardiac lesions and chromosomal abnormalities associated with major fetal heart defects: comparison of intrauterine, postnatal and postmortem diagnoses.

The clinical outcome of prenatally diagnosed congenital heart defects (CHD) continues to be affected significantly by associated extracardiac and chromosomal abnormalities. We sought to: determine the frequency and type of major extracardiac abnormalities (with impact on quality of life) and chromosomal abnormalities associated with fetal CHD; and compare the extracardiac abnormalities detected prenatally to the postnatal and autopsy findings in affected fetuses, to find the incidence of extracardiac abnormalities missed on prenatal ultrasound.

The Early Amniocentesis Study: A Randomized Clinical Trial of Early Amniocentesis versus Midtrimester Amniocentesis

OBJECTIVES The primary purpose of this pilot study was to determine whether the safety of early amniocentesis (EA; 11 weeks to 12 weeks and 6 days) is similar to midtrimester amniocentesis (MA; 15 weeks to 16 weeks and 6 days). The secondary objectives were to determine the cytogenetic success and accuracy of EA compared with MA. METHODS This prospective, randomized clinical trial compared continuous ultrasound-guided EA and MA (22-gauge needle) in patients at a late maternal age (> or = 35 years). The procedures were compared for safety, success and accuracy. RESULTS Among the 683 women randomized and followed to pregnancy completion, there was a total of 27/344 (7.8%) and 25/339 (7.4%) fetal losses (spontaneous and induced abortions) in the EA and MA groups, respectively (difference 0.4%; CI -3.6 to 4.4%). The rate of postprocedure spontaneous fetal loss was 2.4% (8/330) in the EA group and 3.3% (10/299) in the MA group (NS). The procedure success rate at the first attempt was 97.6% in the EA group and 99.7% in the MA group. There were no diagnostic errors, and all but 2 EA cultures were successful (both repeated successfully). The perinatal outcome was similar in both groups. CONCLUSIONS EA appears to be as safe and accurate as MA. A large multicentered, randomized trial is currently underway to verify these results.

Prospective experience with integrated prenatal screening and first trimester combined screening for trisomy 21 in a large Canadian urban center

To evaluate the performance of integrated prenatal screening (IPS) and first trimester combined screening (FTS) for trisomy 21 in a large Canadian urban center.

Tetrasomy 9p Mosaicism Associated with a Normal Phenotype

Isochromosome (tetrasomy) 9p is a rare chromosomal aberration characterized by phenotypic abnormalities ranging from mild developmental delay to multiple anomalies including intrauterine growth retardation, cerebral ventriculomegaly, dysmorphic facial features, cleft lip or palate, abnormal genitalia and renal anomalies. We present a patient with isochromosome (tetrasomy) 9p mosaicism who is a healthy normal adult male with oligospermia who has fathered two normal children. This chromosomal abnormality may be tissue specific, with a higher detection rate in cultured lymphocytes compared with fibroblasts. Therefore, there is an increased chance of missing the abnormality prenatally by amniocentesis or chorionic villus sampling. We are aware of only one other patient in the literature with a normal phenotype associated with mosaicism for this chromosomal abnormality.

A randomised controlled trial of biopsy forceps and cannula aspiration for transcervical chorionic villus sampling

Objective  This trial compared two instruments for transcervical chorionic villus sampling (CVS).

Risk of false-positive prenatal diagnosis using interphase FISH testing: hybridization of alpha-satellite X probe to chromosome 19.

FISH analysis of uncultured interphase amniotic fluid cells from a male fetus revealed two signals using an alpha‐satellite X‐chromosome DNA probe. One of the signals was much smaller than the other. It was subsequently shown that the normal sized signal was located on the X chromosome and the smaller signal was located at the centromere of chromosome 19. This hybridization pattern was confirmed in the newborn infant and in his phenotypically normal father. The use of alpha‐satellite DNA probes on interphase cells could result in false‐positive errors due to rare variants such as the X‐chromosome alpha‐satellite found on chromosome 19 in our patient. Copyright