Methylation-Associated Nucleosomal Patterns of Cell-Free DNA in Cancer Patients and Pregnant Women.

BACKGROUND: Cell-free DNA (cfDNA) analysis offers an attractive noninvasive means of detecting and monitoring diseases. cfDNA cleavage patterns within a short range (e.g., 11 nucleotides) have been reported to correlate with cytosine-phosphate-guanine (CpG) methylation, allowing fragmentomics-based methylation analysis (FRAGMA). Here, we adopted FRAGMA to the extended region harboring multiple nucleosomes, termed FRAGMAXR. METHODS: We profiled cfDNA nucleosomal patterns over the genomic regions from -800 to 800 bp surrounding differentially methylated CpG sites, harboring approximately 8 nucleosomes, referred to as CpG-associated cfDNA nucleosomal patterns. Such nucleosomal patterns were analyzed by FRAGMAXR in cancer patients and pregnant women. RESULTS: We identified distinct cfDNA nucleosomal patterns around differentially methylated CpG sites. Compared with subjects without cancer, patients with hepatocellular carcinoma (HCC) showed reduced amplitude of nucleosomal patterns, with a gradual decrease over tumor stages. Nucleosomal patterns associated with differentially methylated CpG sites could be used to train a machine learning model, resulting in the detection of HCC patients with an area under the receiver operating characteristic curve of 0.93. We further demonstrated the feasibility of multicancer detection using a dataset comprising lung, breast, and ovarian cancers. The tissue-of-origin analysis of plasma cfDNA from pregnant women and cancer patients revealed that the placental DNA and tumoral DNA contributions deduced by FRAGMAXR correlated well with values measured using genetic variants (Pearson r: 0.85 and 0.94, respectively). CONCLUSIONS: CpG-associated cfDNA nucleosomal patterns of cfDNA molecules are influenced by DNA methylation and might be useful for biomarker developments for cancer liquid biopsy and noninvasive prenatal testing.

Effects of elevated sulfate concentration on the mobility of arsenic in the sediment-water interface.

The adsorption/desorption of arsenic (As) at the sediment-water interface in lakes is the key to understanding whether As can enter the ecosystem and participate in material circulation. In this study, the concentrations of As(III), total arsenic [As(T)], sulfide, iron (Fe), and dissolved organic carbon (DOC) in overlying water were observed after the initial sulfate (SO42-) concentrations were increased by four gradients in the presence and absence of microbial systems. The results indicate that increased SO42- concentrations in overlying water triggered As desorption from sediments. Approximately 10% of the desorbed As was desorbed directly as arsenite or arsenate by competitive adsorption sites on the iron salt surface; 21% was due to the reduction of iron (hydr)oxides; and 69% was due to microbial activity, as compared with a system with no microbial activity. The intensity of microbial activity was controlled by the SO42- and DOC concentrations in the overlying water. In anaerobic systems, which had SO42- and DOC concentrations higher than 47 and 7 mg/L, respectively, microbial activity was promoted by SO42- and DOC; As(III) was desorbed under these indoor simulation conditions. When either the SO42- or DOC concentration was lower than its respective threshold of 47 or 7 mg/L, or when either of these indices was below its concentration limit, it was difficult for microorganisms to use SO42- and DOC to enhance their own activities. Therefore, conditions were insufficient for As desorption. The migration of As in lake sediments was dominated by microbial activity, which was co-limited by SO42- and DOC. The concentrations of SO42- and DOC in the overlying water are thus important for the prevention and control of As pollution in lakes. We recommend controlling SO42- and DOC concentrations as a method for controlling As inner-source pollution in lake water.

Circulating tumour DNA analysis for early detection of lung cancer: a systematic review.

Background: Circulating tumor DNA (ctDNA) analysis has been applied in cancer diagnostics including lung cancer. Specifically for the early detection purpose, various modalities of ctDNA analysis have demonstrated their potentials. Such analyses have showed diverse performance across different studies. Methods: We performed a systematic review of original studies published before 1 January 2023. Studies that evaluated ctDNA alone and in combination with other biomarkers for early detection of lung cancer were included. Results: The systematic review analysis included 56 original studies that were aimed for early detection of lung cancer. There were 39 studies for lung cancer only and 17 for pan-cancer early detection. Cancer and control cases included were heterogenous across studies. Different molecular features of ctDNA have been evaluated, including 7 studies on cell-free DNA concentration, 17 on mutation, 29 on methylation, 5 on hydroxymethylation and 8 on fragmentation patterns. Among these 56 studies, 17 have utilised different combinations of the above-mentioned ctDNA features and/or circulation protein markers. For all the modalities, lower sensitivities were reported for the detection of early-stage cancer. Conclusions: The systematic review suggested the clinical utility of ctDNA analysis for early detection of lung cancer, alone or in combination with other biomarkers. Future validation with standardised testing protocols would help integration into clinical care.

Differential 5'-tRNA Fragment Expression in Circulating Preeclampsia Syncytiotrophoblast Vesicles Drives Macrophage Inflammation.

BACKGROUND: The relationship between placental pathology and the maternal syndrome of preeclampsia is incompletely characterized. Mismatch between placental nutrient supply and fetal demands induces stress in the syncytiotrophoblast, the layer of placenta in direct contact with maternal blood. Such stress alters the content and increases the release of syncytiotrophoblast extracellular vesicles (STB-EVs) into the maternal circulation. We have previously shown 5'-tRNA fragments (5'-tRFs) constitute the majority of small RNA in STB-EVs in healthy pregnancy. 5'-tRFs are produced in response to stress. We hypothesized STB-EV 5'-tRF release might change in preeclampsia. METHODS: We perfused placentas from 8 women with early-onset preeclampsia and 6 controls, comparing small RNA expression in STB-EVs. We used membrane-affinity columns to isolate maternal plasma vesicles and investigate placental 5'-tRFs in vivo. We quantified 5'-tRFs from circulating STB-EVs using a placental alkaline phosphatase immunoassay. 5'-tRFs and scrambled RNA controls were added to monocyte, macrophage and endothelial cells in culture to investigate transcriptional responses. RESULTS: 5'-tRFs constitute the majority of small RNA in STB-EVs from both preeclampsia and normal pregnancies. More than 900 small RNA fragments are differentially expressed in preeclampsia STB-EVs. Preeclampsia-dysregulated 5'-tRFs are detectable in maternal plasma, where we identified a placentally derived load. 5'-tRF-Glu-CTC, the most abundant preeclampsia-upregulated 5'-tRF in perfusion STB-EVs, is also increased in preeclampsia STB-EVs from maternal plasma. 5'-tRF-Glu-CTC induced inflammation in macrophages but not monocytes. The conditioned media from 5'-tRF-Glu-CTC-activated macrophages reduced eNOS (endothelial NO synthase) expression in endothelial cells. CONCLUSIONS: Increased release of syncytiotrophoblast-derived vesicle-bound 5'-tRF-Glu-CTC contributes to preeclampsia pathophysiology.

Differential detection of megakaryocytic and erythroid DNA in plasma in hematological disorders.

The tissues of origin of plasma DNA can be revealed by methylation patterns. However, the relative DNA contributions from megakaryocytes and erythroblasts into plasma appeared inconsistent among studies. To shed light into this phenomenon, we developed droplet digital PCR (ddPCR) assays for the differential detection of contributions from these cell types in plasma based on megakaryocyte-specific and erythroblast-specific methylation markers. Megakaryocytic DNA and erythroid DNA contributed a median of 44.2% and 6.2% in healthy individuals, respectively. Patients with idiopathic thrombocytopenic purpura had a significantly higher proportion of megakaryocytic DNA in plasma compared to healthy controls (median: 59.9% versus 44.2%; P = 0.03). Similarly, patients with ß-thalassemia were shown to have higher proportions of plasma erythroid DNA compared to healthy controls (median: 50.9% versus 6.2%) (P < 0.0001). Hence, the concurrent analysis of megakaryocytic and erythroid lineage-specific markers could facilitate the dissection of their relative contributions and provide information on patients with hematological disorders.

Genetic and clinical analysis in Chinese patients with retinitis pigmentosa caused by EYS mutations.

BACKGROUND: Panel-based targeted exome sequencing was applied to identify the pathogenic variants and genetic characteristics of retinitis pigmentosa (RP) in two Chinese families, and to gain a deeper understanding of the relationship between clinical manifestations and genotypes. METHODS: A total of 17 subjects, comprising two probands (total patients: four subjects) and their family member, were recruited in this study. All subjects underwent comprehensive ophthalmic examinations and clinical evaluations, and the complete history and medical records were collected according to the standard procedures. All participants were screened using the multigene panel test (Target_Eye_792_V2 chip), and Sanger sequencing was used to confirm the candidate variants. RESULTS: Among these two families, a total of three novel mutations in the EYS gene were identified in patients, including a homozygous frameshift mutation c.9252_9253insT detected in two patients in one family, and the compound heterozygous splicesite mutation c.5644+2T>C and frameshift mutation c.1920_1923delTGAG detected in two patients in the another family. All patients in both families had early onset of night blindness and poor visual acuity, and with typical posterior capsule opacification. The mutation co-segregated within all recruited individuals. In addition, one patient with compound heterozygous mutations was found to have typical blue-blindness symptoms and detected a previously reported disease-causing mutation c.235G>A in OPN1SW gene, which caused blue blindness manifestations and was first discovered in patient combined with RP causative genes. CONCLUSIONS: Panel-based targeted exome sequencing was used to identify three novel variants of RP causative gene, and we also detected a known pathogenic variants of blue-blindness causative genes in two patients. Our finding will provide a powerful basis for genetic counseling and enhance our current understanding of the genetics factors for RP families.

Genetic and clinical findings of panel-based targeted exome sequencing in a northeast Chinese cohort with retinitis pigmentosa.

BACKGROUND: Panel-based targeted exome sequencing was used to analyze the genetic and clinical findings of targeted genes in a cohort of northeast Chinese with retinitis pigmentosa. METHODS: A total of 87 subjects, comprising 23 probands and their family members (total patients: 32) with confirmed retinitis pigmentosa were recruited in the study. Panel-based targeted exome sequencing was used to sequence the patients and family members, all subjects with retinitis pigmentosa underwent a complete ophthalmologic examination. RESULTS: Of the 23 probands, the clinical manifestations include night blindness, narrowing of vision, secondary cataracts, choroidal atrophy, color blindness, and high myopia, the average age of onset of night blindness is 12.9 ± 14 (range, 0-65; median, 8). Posterior subcapsular opacities is the most common forms of secondary cataracts (nine cases, 39.1%), and peripheral choroidal atrophy is the most common form of secondary choroidal atrophy (12 cases, 52.2%). Of these probands with complication peripheral choroidal atrophy, there were eight probands (66.7%, 8/12) caused by the pathogenic variation in USH2A gene. A total of 17 genes and 45 variants were detected in 23 probands. Among these genes, the commonest genes were USH2A (40%; 18/45), RP1 (15.6%; 7/45), and EYS (8.9%; 4/45), and the top three genes account for 56.5% (13/23) of diagnostic probands. Among these variants, comprising 22 (48.9%) pathogenic variants, 14 (31%) likely pathogenic variants, and nine (20%) uncertain clinical significance variants, and 22 variants was discovered first time. Most of the mutations associated with RP were missense (53.3%, 24/45), and the remaining mutation types include frameshift (35.6%, 16/45), nonsense (6.7%, 3/45), and spliceSite (4.4%, 2/45). Among the probands with mutations detected, compound heterozygous forms was detected in 13 (56.5%, 13/23) probands, and digenic inheritance (DI) forms was detected in five (21.7%, 5/23) probands. CONCLUSION: Panel-based targeted exome sequencing revealed 23 novel mutations, recognized different combinations forms of variants, and extended the mutational spectrum of retinitis pigmentosa and depicted common variants in northeast China.

A start codon mutation of the TSPAN12 gene in Chinese families causes clinical heterogeneous familial exudative vitreoretinopathy.

BACKGROUND: Familial exudative vitreoretinopathy (FEVR) is a severe clinically and genetically heterogeneous retinal disorder characterized with failure of vascular development of the peripheral retina. The symptoms of FEVR vary widely among patients in the same family, and even between the two eyes of a given patient. The purpose of this study was to investigate the molecular mechanisms by which the start codon mutation of the TSPAN12 causes difference in clinical manifestations between individuals in the same family. METHODS: Next-generation sequencing (NGS)-based target capture sequencing was performed in proband with a diagnosis of FEVR and their normal visual acuity family members. Cosegregation analysis of the candidate causative variant was performed in additional family members by using Sanger sequencing. Complete fundus examination, fundus fluorescein angiography (FFA), and family history collection were performed in all family members. Potential candidate causative variants were verified with reference to guidelines and standards from the American College of Medical Genetics and Genomics. RESULTS: We identified a novel heterozygous missense mutation (c.1A>G, p.M1V) localized in the start codon of the TSPAN12 and was detected as a potentially disease-causing variant for the proband. Retrospective analysis of clinical data, fundus examination, and FFA showed that the mutant carrier presented peripheral retinal vascular anomalies in early stages, and visual acuity did not show significant effects. However, the proband who carried this mutation and his cousin showed typical high-stage FEVR fundus changes coupled with a sharp decline in vision. CONCLUSIONS: We report a novel start codon mutation (c.1A>G, p.M1V) in the TSPAN12 that causes clinically heterogeneous manifestations. Our results expand the mutation spectrums of TSPAN12, and will be valuable for disease diagnosis, prognosis, genetic counseling, and enriching our understanding of the role of the tetraspanin-12 protein in the pathogenesis of FEVR.