Screening for aneuploidy in first and second trimesters: is there an optimal paradigm?

Significant polyomic and functional upregulation of the PAPP-A/IGFBP-4/5/IGF-1 axis in chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is associated with epithelial expansion and polyp survival. However, the molecular mechanism of this aberrant proliferation is unclear. The purpose of this study was to interrogate derangements of the pappalysin-A/insulin-like growth factor binding protein/insulin-like growth factor-1 (PAPP-A/IGFBP-4/5/IGF-1 axis) as a major contributing factor to polyp growth in CRSwNP.

METHODS

Matched tissue and exosomal proteomic arrays including PAPP-A, IGFBP-4, IGFBP-5, and IGF-1 were quantified using aptamer-based methods/Western blots for proteomic analysis and whole-transcriptome sequencing/quantitative polymerase chain reaction (qPCR) for transcriptomic analysis in CRSwNP and control patients. Functional PAPP-A assays were then performed in both tissue and exosomes (set 1: n = 20 per group; validation set 2: n = 26 per group).

RESULTS

Tissue and exosomal PAPP-A was significantly overexpressed in CRSwNP compared to controls on both a transcriptomic and proteomic level (p < 0.0001). Known inhibitors of PAPP-A (stanniocalcin-1/-2) were significantly downregulated (p < 0.0001) as were PAPP-A cleavage products (IGFBP-5 p < 0.0001). PAPP-A function was shown to be increased 5-fold to 6-fold in tissue and exosomes.

CONCLUSION

Upregulated tissue and exosomal PAPP-A signaling is significantly associated with CRSwNP and may be an important factor in the promotion of epithelial proliferation and polyp growth. These data lend further support to the emerging concept of exosomal functional and polyomic analyses as a method to study sinonasal pathology.

Explore the dynamic alternation of gene PLAC4 mRNA expression levels in maternal plasma in second trimester for nonivasive detection of trisomy 21

OBJECTIVE

Noninvasive prenatal detection of trisomy 21 (T21) has been achieved by measuring the ratio of two alleles of a single nucleotide polymorphism in circulating placenta specific 4 (PLAC4) mRNA in maternal plasma with a few assays in recent years. Our research is to explore the variations of PLAC4 mRNA expression level in maternal plasma with normal pregnancies in second trimester, which can provide pregnant women deeper insights with suitable detection period for the non-invasive prenatal detection of T21.

METHODS

We measured a serial plasma PLAC4 mRNA concentrations weekly from the same 25 singleton normal pregnant women. We recruited maternal plasma samples from 45 singleton pregnant women, comprising of 25 euploid pregnancies (control group; range, 17 to 21 weeks) and 20 T21 pregnancies (T21 group; range, 19 to 24 weeks). With the application of reverse transcription polymerase chain reaction, we achieved an insight of PLAC4 mRNA expression levels in maternal plasma during second trimester with euploid pregnancies.

RESULTS

Among the control group, the levels of PLAC4 mRNA expression in the gestation of 17 to 18 weeks were significantly less than those in the gestation of 18 to 21 weeks (P<0.05). The average PLAC4 mRNA concentration of the normal pregnant women was not higher than that of the T21 group (P>0.05).

CONCLUSION

The PLAC4 mRNA showed a higher level of expression in the gestation of 18 to 21 weeks with an euploid pregnancy of pregnant women. We also found that there was no significant difference in plasma PLAC4 mRNA concentration between the normal and the T21 pregnancies in second trimester.

Whole-genome reconstruction and mutational signatures in gastric cancer

Background

Gastric cancer is the second highest cause of global cancer mortality. To explore the complete repertoire of somatic alterations in gastric cancer, we combined massively parallel short read and DNA paired-end tag sequencing to present the first whole-genome analysis of two gastric adenocarcinomas, one with chromosomal instability and the other with microsatellite instability.

Results

Integrative analysis and de novo assemblies revealed the architecture of a wild-type KRAS amplification, a common driver event in gastric cancer. We discovered three distinct mutational signatures in gastric cancer - against a genome-wide backdrop of oxidative and microsatellite instability-related mutational signatures, we identified the first exome-specific mutational signature. Further characterization of the impact of these signatures by combining sequencing data from 40 complete gastric cancer exomes and targeted screening of an additional 94 independent gastric tumors uncovered ACVR2A, RPL22 and LMAN1 as recurrently mutated genes in microsatellite instability-positive gastric cancer and PAPPA as a recurrently mutated gene in TP53 wild-type gastric cancer.

Conclusions

These results highlight how whole-genome cancer sequencing can uncover information relevant to tissue-specific carcinogenesis that would otherwise be missed from exome-sequencing data.

A retrospective analysis of amniocenteses performed for advanced maternal age and various other indications in Turkish women

OBJECTIVE

Prenatal cytogenetic diagnostic methods for the diagnosis of fetal chromosomal anomalies have been used reliably over the last 40 years. Advanced maternal age has become a basic indication for amniocentesis.

METHODS

We examined the results of the chromosome analyses of 3485 women that had amniocentesis for any reason during their antenatal care in our perinatology clinic in 2007-2009. Amniocentesis was performed for advanced maternal age in 1456 women (41.8%) and for other reasons in the remaining 2029 women (58.2%). Chromosomal anomalies were examined numerically and structurally.

RESULTS

When the amniocentesis results of the patients were reviewed as numerically normal or abnormal; 40 (2.7%) of 1456 amniocentesis procedures performed for advanced maternal age, 5 (0.9%) of 531 procedures performed for an increased double-test risk and 14 (1.3%) of 1095 procedures performed for an increased triple test risk were found to have chromosomal aneuploidy.

CONCLUSIONS

Maternal age is still the most prevalent indication for genetic amniocentesis other than positive prenatal screening tests. Among women with advanced maternal age, prenatal ultrasonography for soft markers of chromosomal aneuploidy accompanied with maternal serum biochemical screening tests should be evaluated during the decision making process of genetic amniocentesis.

Meeting patients' education and decision-making needs for first trimester prenatal aneuploidy screening

OBJECTIVE

First trimester aneuploidy screening introduces unique challenges to patient education and informed decision-making. Our study assessed the decision-making process among those pregnant patients presenting for this new form of aneuploidy screening.

METHOD

A survey instrument was used to assess components of decision-making among women who presented for first trimester aneuploidy screening. Knowledge and leading factors in the decision-making process were measured.

RESULTS

Participants (n = 139) demonstrated understanding of the etiology of Down syndrome, but less understanding of its cognitive (65.2%) and physical manifestations (58.7%). Few were able to determine risk from first trimester screen results (36.7%). Participants were more familiar with amniocentesis (84.2%) than chorionic villus sampling (73.4%), though less familiar with procedural risks (29.5% and 28.1%, respectively). The majority of participants ranked the following as key information in their decision: knowledge of their intentions about the outcome of the pregnancy based on the test results (92.4%), knowledge of chorionic villus sampling to evaluate an abnormal result (92.0%), and values and beliefs about termination (89.1%).

CONCLUSION

First trimester aneuploidy screening generates education and decision-making benchmarks for patients and providers. It is important to address these barriers as this new screen becomes a growing part of current prenatal genetic testing offerings.

Synergy of total PLAC4 RNA concentration and measurement of the RNA single-nucleotide polymorphism allelic ratio for the noninvasive prenatal detection of trisomy 21

BACKGROUND

Maternal plasma mRNA encoded by the PLAC4 gene (placenta-specific 4), which is transcribed from chromosome 21 in placental cells, is a potential marker for the noninvasive assessment of chromosome 21 dosage in the fetus. We evaluated the diagnostic sensitivities and specificities of 2 trisomy 21-screening approaches that use maternal plasma PLAC4 mRNA.

METHODS

We studied maternal plasma samples from 153 pregnant women carrying euploid and trisomy 21 fetuses. For the samples in which the fetuses were heterozygous for the studied PLAC4 single-nucleotide polymorphism (SNP), we measured the ratio between 2 alleles of the SNP in maternal plasma PLAC4 mRNA (RNA-SNP) by mass spectrometric (MS) and digital PCR methods. For pregnancies involving fetuses homozygous for the SNP, we quantified the total PLAC4 mRNA concentration in maternal plasma by real-time PCR and digital PCR.

RESULTS

For the RNA-SNP approach, we achieved a diagnostic sensitivity and specificity of 100% (95% CI, 40.2%-100%) and 89.7% (95% CI, 78.8%-96.1%), respectively, for both the MS and the digital PCR methods. For the mRNA-quantification approach, the areas under the ROC curves were 0.859 (95% CI, 0.741-0.903) and 0.833 (95% CI, 0.770-0.923) for plasma PLAC4 mRNA concentrations measured by the real-time PCR and the digital PCR methods, respectively.

CONCLUSIONS

For prenatal screening of trisomy 21, the quantification of the total PLAC4 mRNA concentration can be used in a synergistic manner with the RNA-SNP allelic ratio approach to increase the population coverage of cases in which diagnostic information can be obtained.

Triploidies in First and Second Trimesters of Pregnancies in Turkey

Triploidy is the most common chromosomal abnormality in human conceptions that cause fetal loss before 20 weeks of gestation and has an incidence of 1 in 10,000 live births. Placental changes, fetal malformations and intrauterine growth retardation (IUGR) occur in triploid pregnancies. We performed karyotype analyses of 75 spontaneous abortions and 1,114 amniotic fluid cultures by conventional methods between 2002 and 2005 at our cytogenetics laboratory. Triploidy was detected in five spontaneous abortions and four amniotic fluid samples. Abortions were between the 9th and 13th weeks of pregnancy, and cytogenetic analyses revealed a 69, XXY karyotype in four of the aborted fetuses and a 69, XXX karyotype in one. Amniotic fluid cell cultures revealed a 69, XXX karyotype in three cases and 69, XXY in one. Amniocentesis was performed in four patients because of an increased trisomy 18 risk detected in maternal serum screening. In pregnant women undergoing second trimester amniocentesis, increased risk for trisomy 18 may be due to triploidy and should be taken into account during genetic counseling.