Project description:Noninvasive prenatal diagnosis currently used does not achieve desirable levels of sensitivity and specificity. Recently, fetal methylated DNA biomarkers in maternal whole blood have been explored for noninvasive prenatal detection. However, such efforts cover only chromosomal aneuploidy; fetal methylated DNA biomarkers for detecting single-gene disease remain to be discovered. To address this issue, we systematically screened significantly hypermethylated genes in fetal tissues compared with maternal blood for noninvasive prenatal diagnosis of various inherited diseases. First, Methylated-CpG island recovery assay combined with CpG island array was performed in four maternal peripheral bloods and their corresponding placental tissues. Subsequently, direct bisulfite sequencing and combined bisulfite restriction analysis (COBRA) were carried out to validate the reliability of methylation microarray analysis. As results, 310 significantly hypermethylated genes in fetal tissues were detected by microarray. Two of five randomly selected hypermethylated genes detected by microarray were confirmed to be hypermethylated in fetal tissue samples by direct bisulfite sequencing. All four randomly selected hypermethylated genes detected by microarray were confirmed to be hypermethylated in five independent amniotic fluid samples and five independent chorionic villus samples from 10 pregnant women by CORBA. In conclusions, We found a lot of hypermethylated genes and methylation sites in fetal tissues, some of which have great potential to be developed into molecular markers for noninvasive prenatal diagnosis of monogenic disorders. Further clinical study is warranted to confirm these findings. Paired experiments, placental tissues vs. maternal peripheral bloods. Biological replicates: 4 placental tissues and 4 correspoding maternal peripheral bloods.
Project description:Whereas non-invasive prenatal testing for aneuploidies (NIPT-A) is widely implemented, non-invasive prenatal testing for monogenic diseases (NIPT-M) is lagging. By capturing and targeted sequencing of 250000 polymorphic SNP loci from maternal plasma circulating cell-free DNA (cfDNA) and DNA from relatives, the fetal haplotype and chromosomal copy numbers are deduced. In all families tested, the cfDNA derived haplotypes are on average 97% concordant with the neonatal and embryo haplotype. This generic non-invasive prenatal diagnostic approach allows cost efficient scrutinizing the fetal genome for the presence of any inherited monogenic disease or trait.
Project description:Noninvasive prenatal diagnosis currently used does not achieve desirable levels of sensitivity and specificity. Recently, fetal methylated DNA biomarkers in maternal whole blood have been explored for noninvasive prenatal detection. However, such efforts cover only chromosomal aneuploidy; fetal methylated DNA biomarkers for detecting single-gene disease remain to be discovered. To address this issue, we systematically screened significantly hypermethylated genes in fetal tissues compared with maternal blood for noninvasive prenatal diagnosis of various inherited diseases. First, Methylated-CpG island recovery assay combined with CpG island array was performed in four maternal peripheral bloods and their corresponding placental tissues. Subsequently, direct bisulfite sequencing and combined bisulfite restriction analysis (COBRA) were carried out to validate the reliability of methylation microarray analysis. As results, 310 significantly hypermethylated genes in fetal tissues were detected by microarray. Two of five randomly selected hypermethylated genes detected by microarray were confirmed to be hypermethylated in fetal tissue samples by direct bisulfite sequencing. All four randomly selected hypermethylated genes detected by microarray were confirmed to be hypermethylated in five independent amniotic fluid samples and five independent chorionic villus samples from 10 pregnant women by CORBA. In conclusions, We found a lot of hypermethylated genes and methylation sites in fetal tissues, some of which have great potential to be developed into molecular markers for noninvasive prenatal diagnosis of monogenic disorders. Further clinical study is warranted to confirm these findings.
Project description:We revealed a large population of long cell-free DNA molecules (up to 23,635 bp in length) in maternal plasma and developed an approach which leveraged the abundance of CpG sites on long molecules to deduce the tissue of origin of individual plasma DNA molecules based on single-molecule methylation analysis. We illustrated how such an approach may be utilized to achieve noninvasive prenatal testing of monogenic diseases. We also revealed a reduction in amounts of such long cell-free DNA molecules and a different end motif profile in maternal plasma DNA from pregnancies with preeclampsia.
Project description:<p>In the last decade, non-invasive prenatal diagnosis (NIPD) has emerged as an effective procedure for early detection of inherited diseases during pregnancy. This technique is based on using cell-free DNA (cfDNA) and fetal cfDNA (cffDNA) in maternal blood, and hence, has minimal risk for the mother and fetus compared with invasive techniques. NIPD is used today for identifying chromosomal abnormalities (in some instances) and for single-gene disorders (SGDs) of paternal origin. However, for SGDs of maternal origin, sensitivity poses a challenge that limits the testing to one genetic disorder at a time. Here we present a Bayesian method for the NIPD of monogenic diseases that is independent of the mode of inheritance and parental origin. Furthermore, we show that accounting for differences in the fragment length distribution of fetal- and maternal-derived cfDNA results in increased accuracy. Our model is the first to predict inherited insertions-deletions (indels). The method described can serve as a general framework for the NIPD of SGDs; this will facilitate easy integration of further improvements. One such improvement that is presented in the current study is a machine learning model that corrects errors based on patterns found in previously processed data. Overall, we show that next generation sequencing (NGS) can be used for the NIPD of a wide range of monogenic diseases, simultaneously. We believe that our study will lead to the achievement of a comprehensive NIPD for monogenic diseases.</p> <p>(Reprinted from Bayesian-based noninvasive prenatal diagnosis of single-gene disorders, with permission from Genome Research) </p>
Project description:Fetal DNA is present in the plasma of pregnant women. Massively parallel sequencing of maternal plasma DNA has been used to detect fetal trisomies 21, 18, 13 and selected sex chromosomal aneuploidies noninvasively. Case reports describing the detection of fetal microdeletions from maternal plasma using massively parallel sequencing have been reported. However, these previous reports were either polymorphism-dependent or used statistical analyses which were confined to one or a small number of selected parts of the genome. In this report, we reported a procedure for performing noninvasive prenatal karyotyping at 3 Mb resolution across the whole genome through the massively parallel sequencing of maternal plasma DNA. This method has been used to analyze the plasma obtained from 6 cases. In 5 cases, fetal microduplications or microdeletions have been detected successfully from maternal plasma. The two cases with fetal microduplications represented the first noninvasive prenatal detection of such changes from maternal plasma. In the remaining case, the plasma DNA sequencing result was consistent with the pregnant mother being a carrier of a microduplication. Simulation analyses were performed for determining the number of plasma DNA molecules that would need to be sequenced and aligned for enhancing the diagnostic resolution of noninvasive prenatal karyotyping to 2 Mb and 1 Mb. In conclusion, noninvasive prenatal molecular karyotyping from maternal plasma by massively parallel sequencing is feasible and would enhance the diagnostic spectrum of noninvasive prenatal testing.
Project description:Noninvasive prenatal testing using massively parallel sequencing of maternal plasma DNA has been rapidly adopted in clinical use worldwide. Fetal DNA fraction in a maternal plasma sample is an important parameter for accurate interpretations of these tests. However, there is a lack of methods involving low-sequencing depth and yet would allow a robust and accurate determination of fetal DNA fraction in maternal plasma for all pregnancies. In this study, we have developed a new method to accurately quantify the fetal DNA fraction by analysing the maternal genotypes and sequencing data of maternal plasma DNA. Fetal DNA fraction was calculated based on the proportion of non-maternal alleles at single-nucleotide polymorphisms where the mother is homozygous. This new approach achieves a median deviation of 0.6% between predicted fetal DNA fraction and the actual fetal DNA fraction using as low as 0.03-fold sequencing coverage of the human genome. We believe that this method will further enhance the clinical interpretations of noninvasive prenatal testing using genome-wide random sequencing.
Project description:The discovery of fetal mRNA transcripts in maternal circulation holds great promise for noninvasive prenatal diagnosis. To identify potential fetal biomarkers, we studied whole blood and plasma transcripts common to term pregnant women and their newborns but reduced or absent in the postpartum mothers. In whole blood, 157 potentially-fetal transcripts were identified. RT-PCR confirmed the presence of specific transcripts, SNP analysis confirmed the presence of fetal transcripts in maternal circulation. Comparison of whole blood and plasma samples from the same women suggested that placental genes are more easily detected in plasma. We conclude that fetal and placental mRNA circulates in the blood of pregnant women.