Preimplantation genetic screening (PGS) is widely used to select in vitro-fertilized embryos free of chromosomal abnormalities and to improve the clinical outcome of in vitro fertilization (IVF). A disadvantage of PGS is that it requires biopsy of the preimplantation human embryo, which can limit the clinical applicability of PGS due to the invasiveness and complexity of the process. Here, we present and validate a noninvasive chromosome screening (NICS) method based on sequencing the genomic DNA secreted into the culture medium from the human blastocyst. By using multiple annealing and looping-based amplification cycles (MALBAC) for whole-genome amplification (WGA), we performed next-generation sequencing (NGS) on the spent culture medium used to culture human blastocysts (n = 42) and obtained the ploidy information of all 24 chromosomes. We validated these results by comparing each with their corresponding whole donated embryo and obtained a high correlation for identification of chromosomal abnormalities (sensitivity, 0.882, and specificity, 0.840). With this validated NICS method, we performed chromosome screening on IVF embryos from seven couples with balanced translocation, azoospermia, or recurrent pregnancy loss. Six of them achieved successful clinical pregnancies, and five have already achieved healthy live births thus far. The NICS method avoids the need for embryo biopsy and therefore substantially increases the safety of its use. The method has the potential of much wider chromosome screening applicability in clinical IVF, due to its high accuracy and noninvasiveness.
To explore new molecular diagnosis approaches for early detection and differential diagnosis of hepatocellular carcinoma (HCC), we analyzed genomic copy number variations (CNV) using plasma cell-free DNA from patients with HCC by next generation DNA sequencing. Plasma samples from 31 patients with HCC and 8 patients with chronic hepatitis or cirrhosis were analyzed. In HCC group, most samples with large tumor size (tumor dimension greater than 50 mm) showed CNVs that are visually recognizable at chromosome CNV plots, few samples with small tumor and none samples with chronic liver diseases showed CNVs recognizable at CNV plots. CNV Z score analysis showed significant CNVs in samples with HCC and chronic liver diseases although more significant changes were found in HCC group, some are differentially valuable (such as gain in 1q, 7q, and 19q in HCC), while others are less differentially valuable (such as loss in 4q, 13q, gain in 17q, 22q). We proposed a CNV scoring method that generated positive result in 26 of the 31 HCC patients (83.9%) or 11 of the 16 HCC with tumor dimension 50 mm or less (68.8%) or 4 of the 7 HCC with tumor dimension 30 mm or less (57.1%), while all the 8 samples with chronic hepatitis or cirrhosis scored negative. Ten HCC patients had normal or low serum AFP levels, among them, 7 were scored positive by CNV analysis, including 4 with tumor dimension 50 mm or less. Our study suggested that non-invasive genomic CNV analysis using plasma samples could be a valuable tool for early detection and differential diagnosis of HCC. Although CNV analysis itself cannot establish the diagnosis, it can help identify patients at high risk for HCC among patients with chronic liver diseases, which would prompt closer and more frequent surveillance for early tumor detection and intervention.
Reciprocal translocations (RecT) and Robertsonian translocations (RobT) are among the most common chromosomal abnormalities that cause infertility and birth defects. Preimplantation genetic testing for aneuploidy using comprehensive chromosome screening for in vitro fertilization enables embryo selection with balanced chromosomal ploidy; however, it is normally unable to determine whether an embryo is a translocation carrier. Here we report a method named "Mapping Allele with Resolved Carrier Status" (MaReCs), which enables chromosomal ploidy screening and resolution of the translocation carrier status of the same embryo. We performed MaReCs on 108 embryos, of which 96 were from 13 RecT carriers and 12 were from three RobT carriers. Thirteen of the sixteen patients had at least one diploid embryo. We have confirmed the accuracy of our carrier status determination in amniotic fluid karyotyping of seven cases as well as in the live birth we have thus far. Therefore, MaReCs accurately enables the selection of translocation-free embryos from patients carrying chromosomal translocations. We expect MaReCs will help reduce the propagation of RecT/RobT in the human population.
BackgroundEndogenous non-coding small RNAs (21-24 nt) play an important role in post-transcriptional gene regulation in plants. Domestication selection is the most important evolutionary force in shaping crop genomes. The extent of polymorphism at small RNA loci in domesticated rice and whether small RNA loci are targets of domestication selection have not yet been determined.ResultsA polymorphism survey of 94 small RNA loci (88 MIRNAs, four TAS3 loci and two miRNA-like long hairpins) was conducted in domesticated rice, generating 2 Mb of sequence data. Many mutations (substitution or insertion/deletion) were observed at small RNA loci in domesticated rice, e.g. 12 mutation sites were observed in the mature miRNA sequences of 11 MIRNAs (12.5% of the investigated MIRNAs). Several small RNA loci showed significant signals for positive selection and/or potential domestication selection.ConclusionsSequence variation at miRNAs and other small RNAs is higher than expected in domesticated rice. Like protein-coding genes, non-coding small RNA loci could be targets of domestication selection and play an important role in rice domestication and improvement.
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