A case of TFE3 translocation renal cell carcinoma with rare morphological features and literature review.

Context: TFE3 translocation renal cell carcinoma (RCC) is a rare tumor that represents approximately 1% of RCC. It was classifed as a member of MiT family translocation RCCs by the World Health Organization in 2016. It is characterized by Xp11 translocation gene fusions involving TFE3. The diagnosis of TFE3 translocation RCC is based on immunohistochemical analysis and TFE3 break apart probes in FISH analysis, rather than histological characteristics and imaging examination. Aims: To determine the clinico-pathological, immuno-phenotypic, and cytogenetic characteristics of TFE3 translocation RCC. Methods and Materials: The clinical data of a 52-year-old-female patient with TFE3 translocation RCC exhibiting rare morphological characteristics was analyzed, and the tumor tissues were probed using histopathological staining, immunohistochemistry, and fluorescence in situ hybridization (FISH). In addition, the relevant literature was reviewed. Results: This case is a TFE3 translocation RCC with rare morphological features. It composed of two types of tumor cells. TFE3 and pax-8 were diffusely and strongly expressed in both tumor cells, and they were partially positive for CAIX, RCC, CK, EMA, CD10, Vim, Melan-A, and p504s. Only 2% of the cells were positive for the proliferation marker Ki-67, and the tumor was negative for CK7, CD117, Inhibin-α, HBM45, and p53. FISH showed a positive signal for TFE3 translocation. Conclusions: This case was a TFE3 translocation RCC with rare morphological features. Through this case report, we emphasize the importance of in situ detection of TFE3 gene translocation and protein in TFE3 translocation RCC.

Renal cancer associated with Xp11.2 translocation/TFE3 gene fusion: Clinicopathological analysis of 13 cases.

OBJECTIVE: To explore the clinicopathological characteristics, immunohistochemical phenotype, diagnosis and differential diagnosis of renal cell carcinoma associated with Xp11.2 translocation/TFE3 gene fusion. METHODS: The clinical history, pathological morphology, immunohistochemical phenotype and related molecular test results of 13 cases of Xp11.2 translocation/TFE3 gene fusion-related renal cell carcinoma were retrospectively analyzed, and the relevant literature was reviewed. RESULTS: Of the 13 patients, 5 were males and 8 were females. The age of onset ranges from 8 to 73 years old, most of which were middle-aged and elderly patients. Among them, there were 3 cases of left kidney tumor and 10 cases of right kidney tumor. In the treatment method, 2 of the 13 patients underwent partial nephrectomy, and 11 underwent radical nephrectomy. Histopathological morphology showed papillary, nested, tubular and acinar structures. The cytoplasm was transparent or eosinophilic, and the interstitial fibrosis was accompanied by chronic inflammatory cell infiltration, hemosiderin deposition and foam cell aggregation. The immunohistochemical analysis of 13 patient specimens all expressed TFE3 antibody, and the expression intensity was strongly positive; gene FISH detection technology revealed the breakage and rearrangement of TFE3 gene in 12 assessable cases. One of thirteen patients had a metastasis at follow-up from 3 to 69 months. CONCLUSIONS: This type of kidney cancer was a rare subtype. Because of its complex and changeable shape, it has a high degree of overlap with other kidney cancer subtypes, and the missed diagnosis rate and misdiagnosis rate are extremely high. The diagnosis is mainly based on pathomorphology and immunohistochemistry, TFE3 positive expression and TFE3 gene destruction and rearrangement.

TAD-like single-cell domain structures exist on both active and inactive X chromosomes and persist under epigenetic perturbations.

BACKGROUND: Topologically associating domains (TADs) are important building blocks of three-dimensional genome architectures. The formation of TADs has been shown to depend on cohesin in a loop-extrusion mechanism. Recently, advances in an image-based spatial genomics technique known as chromatin tracing lead to the discovery of cohesin-independent TAD-like structures, also known as single-cell domains, which are highly variant self-interacting chromatin domains with boundaries that occasionally overlap with TAD boundaries but tend to differ among single cells and among single chromosome copies. Recent computational modeling studies suggest that epigenetic interactions may underlie the formation of the single-cell domains. RESULTS: Here we use chromatin tracing to visualize in female human cells the fine-scale chromatin folding of inactive and active X chromosomes, which are known to have distinct global epigenetic landscapes and distinct population-averaged TAD profiles, with inactive X chromosomes largely devoid of TADs and cohesin. We show that both inactive and active X chromosomes possess highly variant single-cell domains across the same genomic region despite the fact that only active X chromosomes show clear TAD structures at the population level. These X chromosome single-cell domains exist in distinct cell lines. Perturbations of major epigenetic components and transcription mostly do not affect the frequency or strength of the single-cell domains. Increased chromatin compaction of inactive X chromosomes occurs at a length scale above that of the single-cell domains. CONCLUSIONS: In sum, this study suggests that single-cell domains are genome architecture building blocks independent of the tested major epigenetic components.

Novel G-quadruplex prone sequences emerge in the complete assembly of the human X chromosome.

G-quadruplexes are non-B secondary structures with regulatory functions and therapeutic potential. Improvements in sequencing methods recently allowed the completion of the first human chromosome which is now available as a gapless, end-to-end assembly, with the previously remaining spaces filled and newly identified regions added. We compared the presence of G-quadruplex forming sequences in the current human reference genome (GRCh38) and in the new end-to-end assembly of the X chromosome constructed by high-coverage ultra-long-read nanopore sequencing. This comparison revealed that, even though the corrected length of the chromosome X assembly is surprisingly 1.14% shorter than expected, the number of G-quadruplex forming sequences found in this gapless chromosome is significantly higher, with 493 new motifs having G4Hunter scores above 1.4 and 23 new sequences with G4Hunter scores above 3.5. This observation reflects an improved precision of the new sequencing approaches and points to an underestimation of G-quadruplex propensity in the previous, widely used version of the human genome assembly, especially for motifs with a high G4Hunter score, expected to be very stable. These G-quadruplex forming sequences probably remained undiscovered in earlier genome datasets due to previously unsolved G-rich and repetitive genomic regions. These observations allow a precise targeting of these important regulatory regions.

Artificial escape from XCI by DNA methylation editing of the CDKL5 gene.

A significant number of X-linked genes escape from X chromosome inactivation and are associated with a distinct epigenetic signature. One epigenetic modification that strongly correlates with X-escape is reduced DNA methylation in promoter regions. Here, we created an artificial escape by editing DNA methylation on the promoter of CDKL5, a gene causative for an infantile epilepsy, from the silenced X-chromosomal allele in human neuronal-like cells. We identify that a fusion of the catalytic domain of TET1 to dCas9 targeted to the CDKL5 promoter using three guide RNAs causes significant reactivation of the inactive allele in combination with removal of methyl groups from CpG dinucleotides. Strikingly, we demonstrate that co-expression of TET1 and a VP64 transactivator have a synergistic effect on the reactivation of the inactive allele to levels >60% of the active allele. We further used a multi-omics assessment to determine potential off-targets on the transcriptome and methylome. We find that synergistic delivery of dCas9 effectors is highly selective for the target site. Our findings further elucidate a causal role for reduced DNA methylation associated with escape from X chromosome inactivation. Understanding the epigenetics associated with escape from X chromosome inactivation has potential for those suffering from X-linked disorders.

Amplification-by-Polymerization in Biosensing for Human Genomic DNA Detection.

A polymerization reaction was employed as a signal amplification method to realize direct visualization of gender-specific DNA extracted from human blood in a polymerase chain reaction (PCR)-free fashion. Clear distinction between X and Y chromosomes was observed by naked eyes for detector-free sensing purposes. The grown polymer films atop X and Y chromosomes were quantitatively measured by ellipsometry for thickness readings. Detection assays have been optimized for genomic DNA recognition to a maximum extent by varying the selection of the proper blocking reagents, the annealing temperature, and the annealing time. Traditional PCR and gel electrophoresis for amplicon identification were conducted in parallel for performance comparison. In the blind test for blood samples examined by the new approach, 25 out of 26 were correct and one was false negative, which was comparable to, if not better than, the PCR results. This is the first time our amplification-by-polymerization technique is being used for chromosome DNA analysis. The potential of adopting the described sensing technique without PCR was demonstrated, which could further promote the development of a portable, PCR-free DNA sensing device for point-of-need applications.

En bloc and segmental deletions of human XIST reveal X chromosome inactivation-involving RNA elements.

The XIST RNA is a non-coding RNA that induces X chromosome inactivation (XCI). Unlike the mouse Xist RNA, how the human XIST RNA controls XCI in female cells is less well characterized, and its functional motifs remain unclear. To systematically decipher the XCI-involving elements of XIST RNA, 11 smaller XIST segments, including repeats A, D and E; human-specific repeat elements; the promoter; and non-repetitive exons, as well as the entire XIST gene, were homozygously deleted in K562 cells using the Cas9 nuclease and paired guide RNAs at high efficiencies, followed by high-throughput RNA sequencing and RNA fluorescence in situ hybridization experiments. Clones containing en bloc and promoter deletions that consistently displayed no XIST RNAs and a global up-regulation of X-linked genes confirmed that the deletion of XIST reactivates the inactive X chromosome. Systematic analyses of segmental deletions delineated that exon 5 harboring the non-repeat element is important for X-inactivation maintenance, whereas exons 2, 3 and 4 as well as the other repeats in exon 1 are less important, a different situation from that of mouse Xist. This Cas9-assisted dissection of XIST allowed us to understand the unique functional domains within the human XIST RNA.

Rare copy number variants in the genome of Chinese female children and adolescents with Turner syndrome.

Turner syndrome (TS) is a congenital disease caused by complete or partial loss of one X chromosome. Low bone mineral status is a major phenotypic characteristic of TS that can not be fully explained by X chromosome loss, suggesting other autosomal-linked mutations may also exist. Therefore, the present study aimed to detect potential genetic mutations in TS through examination of copy number variation (CNV). Seventeen patients with TS and 15 healthy volunteer girls were recruited. Array-based comparative genomic hybridization (a-CGH) was performed on whole blood genomic DNA (gDMA) from the 17 TS patients and 15 healthy volunteer girls to identify potential CNVs. The abnormal CNV of one identified gene (CARD11) was verified by quantitative PCR. All cases diagnosed had TS based on genotype examination and physical characteristics, including short stature and premature ovarian failure. Three rare CNVs, located individually at 7p22.3, 7p22.2, and Xp22.33, where six genes (TTYH3, AMZ1, GNA12, BC038729, CARD11, and SHOX (stature homeobox)) are located, were found in TS patients. Quantitative PCR confirmed the CNV of CARD11 in the genome of TS patients. Our results indicate that CARD11 gene is one of the mutated genes involved in TS disease. However, this CNV is rare and its contribution to TS phenotype requires further study.

Potentially effective method for fetal gender determination by noninvasive prenatal testing for X-linked disease.

Examination of maternal plasma cell-free DNA (cfDNA) for noninvasive prenatal testing for fetal trisomy is a highly effective method for pregnant women at high risk. This can be also applied to fetal gender determination in female carriers of severe X-linked disease. Polymerase chain reaction (PCR) analysis is a relatively simpler and less expensive method of detecting Y chromosome-specific repeats (Y-specific PCR; YSP), but is limited by the risk of false-negative results. To address this, we have developed a combined strategy incorporating YSP and an estimation of the fetal DNA fraction. Multiplex PCR for 30 single nucleotide polymorphism (SNP) loci selected by high heterozygosity enables the robust detection of the fetal DNA fraction in cfDNA. The cfDNA sample is first subjected to YSP. When the YSP result is positive, the fetus is male and invasive testing for an X-linked mutation is then required. When the YSP result is negative, the cfDNA sample is analyzed using multiplex PCR. If fetal DNA is then found in the cfDNA, invasive testing is not then required. If the multiplex PCR analysis of cfDNA is negative for fetal DNA, the fetal gender cannot be determined and invasive testing is still required. Our technique provides a potentially effective procedure that can help to avoid unnecessary invasive prenatal testing in some female carriers of severe X-linked disease.

Exonic duplication of the OTC gene by a complex rearrangement that likely occurred via a replication-based mechanism: a case report.

BACKGROUND: Ornithine transcarbamylase deficiency (OTCD) is an X-linked recessive disorder involving a defect in the urea cycle caused by OTC gene mutations. Although a total of 417 disease-causing mutations in OTC have been reported, structural abnormalities in this gene are rare. We here describe a female OTCD case caused by an exonic duplication of the OTC gene (exons 1-6). CASE PRESENTATION: A 23-year-old woman with late-onset OTCD diagnosed by biochemical testing was subjected to subsequent genetic testing. Sanger sequencing revealed no pathogenic mutation throughout the coding exons of the OTC gene, but multiplex ligation-dependent probe amplification (MLPA) revealed duplication of exons 1-6. Further genetic analyses revealed an inversion of duplicated exon 1 and a tandem duplication of exons 2-6. Each of the junctions of the inversion harbored a microhomology and non-templated microinsertion, respectively, suggesting a replication-based mechanism. The duplication was also of de novo origin but segregation analysis indicated that it took place in the paternal chromosome. CONCLUSION: We report the first OTCD case harboring an exonic duplication in the OTC gene. The functional defects caused by this anomaly were determined via structural analysis of its complex rearrangements.

Parental haplotype-specific single-cell transcriptomics reveal incomplete epigenetic reprogramming in human female germ cells.

In contrast to mouse, human female germ cells develop asynchronously. Germ cells transition to meiosis, erase genomic imprints, and reactivate the X chromosome. It is unknown if these events all appear asynchronously, and how they relate to each other. Here we combine exome sequencing of human fetal and maternal tissues with single-cell RNA-sequencing of five donors. We reconstruct full parental haplotypes and quantify changes in parental allele-specific expression, genome-wide. First we distinguish primordial germ cells (PGC), pre-meiotic, and meiotic transcriptional stages. Next we demonstrate that germ cells from various stages monoallelically express imprinted genes and confirm this by methylation patterns. Finally, we show that roughly 30% of the PGCs are still reactivating their inactive X chromosome and that this is related to transcriptional stage rather than fetal age. Altogether, we uncover the complexity and cell-to-cell heterogeneity of transcriptional and epigenetic remodeling in female human germ cells.

A novel small deletion in the NHS gene associated with Nance-Horan syndrome.

Nance-Horan syndrome is a rare X-linked recessive inherited disease with clinical features including severe bilateral congenital cataracts, characteristic facial and dental abnormalities. Data from Chinese Nance-Horan syndrome patients are limited. We assessed the clinical manifestations of a Chinese Nance-Horan syndrome pedigree and identified the genetic defect. Genetic analysis showed that 3 affected males carried a novel small deletion in NHS gene, c.263_266delCGTC (p.Ala89TrpfsTer106), and 2 female carriers were heterozygous for the same variant. All 3 affected males presented with typical Nance-Horan syndrome features. One female carrier displayed lens opacities centered on the posterior Y-suture in both eyes, as well as mild dental abnormalities. We recorded the clinical features of a Chinese Nance-Horan syndrome family and broadened the spectrum of mutations in the NHS gene.

Genome-wide DNA methylation profiling using the methylation-dependent restriction enzyme LpnPI.

DNA methylation is a well-known epigenetic modification that plays a crucial role in gene regulation, but genome-wide analysis of DNA methylation remains technically challenging and costly. DNA methylation-dependent restriction enzymes can be used to restrict CpG methylation analysis to methylated regions of the genome only, which significantly reduces the required sequencing depth and simplifies subsequent bioinformatics analysis. Unfortunately, this approach has been hampered by complete digestion of DNA in CpG methylation-dense regions, resulting in fragments that are too small for accurate mapping. Here, we show that the activity of DNA methylation-dependent enzyme, LpnPI, is blocked by a fragment size smaller than 32 bp. This unique property prevents complete digestion of methylation-dense DNA and allows accurate genome-wide analysis of CpG methylation at single-nucleotide resolution. Methylated DNA sequencing (MeD-seq) of LpnPI digested fragments revealed highly reproducible genome-wide CpG methylation profiles for >50% of all potentially methylated CpGs, at a sequencing depth less than one-tenth required for whole-genome bisulfite sequencing (WGBS). MeD-seq identified a high number of patient and tissue-specific differential methylated regions (DMRs) and revealed that patient-specific DMRs observed in both blood and buccal samples predict DNA methylation in other tissues and organs. We also observed highly variable DNA methylation at gene promoters on the inactive X Chromosome, indicating tissue-specific and interpatient-specific escape of X Chromosome inactivation. These findings highlight the potential of MeD-seq for high-throughput epigenetic profiling.

Multi-allelic exact tests for Hardy-Weinberg equilibrium that account for gender.

Statistical tests for Hardy-Weinberg equilibrium are important elementary tools in genetic data analysis. X-chromosomal variants have long been tested by applying autosomal test procedures to females only, and gender is usually not considered when testing autosomal variants for equilibrium. Recently, we proposed specific X-chromosomal exact test procedures for bi-allelic variants that include the hemizygous males, as well as autosomal tests that consider gender. In this study, we present the extension of the previous work for variants with multiple alleles. A full enumeration algorithm is used for the exact calculations of tri-allelic variants. For variants with many alternate alleles, we use a permutation test. Some empirical examples with data from the 1,000 genomes project are discussed.

Social selection favours offspring prone to the development of androgenetic alopecia.

In recent years, dermatologists have observed an increase in the incidence of male androgenetic alopecia (AGA). In a survey of 41 dermatologists, 88% reported an increase in incidence of AGA in men younger than 30 years. This phenomenon has no apparent explanation. However, due to the strong genetic inheritance component of AGA, a social or environmental factor which favours the inheritance of genes that increase the risk of developing AGA is suspected. To date, the strongest predictor of AGA in men has been the length of the CAG repeat located in the androgen receptor gene (AR gene) on the X chromosome. The same genetic variant in women is associated with ovulation at a later age, higher antral follicle count, and lower risk for premature ovarian failure. This led us to theorize that, due to social pressure to conceive later in life, women carriers of the short CAG repeat in the AR gene would have a selective advantage to conceive later in life and would thus favour male offspring exhibiting AGA.

First report on an X-linked hypohidrotic ectodermal dysplasia family with X chromosome inversion: Breakpoint mapping reveals the pathogenic mechanism and preimplantation genetics diagnosis achieves an unaffected birth.

BACKGROUND: To investigate the etiology of X-linked hypohidrotic ectodermal dysplasia (XLHED) in a family with an inversion of the X chromosome [inv(X)(p21q13)] and to achieve a healthy birth following preimplantation genetic diagnosis (PGD). METHODS: Next generation sequencing (NGS) and Sanger sequencing analysis were carried out to define the inversion breakpoint. Multiple displacement amplification, amplification of breakpoint junction fragments, Sanger sequencing of exon 1 of ED1, haplotyping of informative short tandem repeat markers and gender determination were performed for PGD. RESULTS: NGS data of the proband sample revealed that the size of the possible inverted fragment was over 42Mb, spanning from position 26, 814, 206 to position 69, 231, 915 on the X chromosome. The breakpoints were confirmed by Sanger sequencing. A total of 5 blastocyst embryos underwent trophectoderm biopsy. Two embryos were diagnosed as carriers and three were unaffected. Two unaffected blastocysts were transferred and a singleton pregnancy was achieved. Following confirmation by prenatal diagnosis, a healthy baby was delivered. CONCLUSIONS: This is the first report of an XLHED family with inv(X). ED1 is disrupted by the X chromosome inversion in this XLHED family and embryos with the X chromosomal abnormality can be accurately identified by means of PGD.

[Method for the Molecular Cytogenetic Visualization of Fragile Site FRAXA].

Fragile X syndrome is one of the most common reasons for human hereditary mental retardation. It is associated with the expansion of CGG repeats in the 5'-untranslated region of the FMR1 gene, which results in the suppression of its expression and the development of the disease. At present, methods based on PCR and Southern blot analysis are used for diagnostics of the fragile X syndrome. The presence of a fragile site FRAXA on the X chromosome is typical for patients with this pathology. We developed a method of visualizing this site in cell cultures obtained from patients using the fluorescent in situ hybridization (FISH) and the combination of two probes. The method allows one to detect five types of signals on the X chromosome, three of which are normal, while two are associated with the emergence of fragile site FRAXA. An analysis of the distribution of all signal types in cell lines from healthy individuals and patients with fragile X syndrome demonstrated that the method allows one to determine differences between lines with a high statistical significance and that it is applicable to detecting cells that are carriers of the syndrome.

Gene ORGANizer: linking genes to the organs they affect.

One of the biggest challenges in studying how genes work is understanding their effect on the physiology and anatomy of the body. Existing tools try to address this using indirect features, such as expression levels and biochemical pathways. Here, we present Gene ORGANizer (geneorganizer.huji.ac.il), a phenotype-based tool that directly links human genes to the body parts they affect. It is built upon an exhaustive curated database that links >7000 genes to ∼150 anatomical parts using >150 000 gene-organ associations. The tool offers user-friendly platforms to analyze the anatomical effects of individual genes, and identify trends within groups of genes. We demonstrate how Gene ORGANizer can be used to make new discoveries, showing that chromosome X is enriched with genes affecting facial features, that positive selection targets genes with more constrained phenotypic effects, and more. We expect Gene ORGANizer to be useful in a variety of evolutionary, medical and molecular studies aimed at understanding the phenotypic effects of genes.